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Preharvest Management Options for Wheat

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Winter wheat, if not already there, is quickly approaching physiological maturity. The earliest seeded spring wheat is soon to follow. And thus, it is time to evaluate your pre-harvest management options. Follow this link to read a quick review of your options. Although there are very persistent assertions, pre-harvest glyphosate - when applied according to the label - should not result in changes in grain protein. A summary of a study to debunk this myth can be found here


HRSW varieties differ for their resistance to pre-harvest sprouting. This high-temperature dormancy peaks at physiological maturity. Repeated wetting and drying of the grain in a swath or even while standing will degrade this dormancy over time. The dormancy of some varieties break down sooner than other, potentially resulting in sprout damage. Click here to look up the ratings for the current HRSW varieties. The best remedy to avoid pre-harvest sprout damage is to harvest timely, even if that means that you are above 13.5% grain moisture content

Finally, many wheat fields are showing tall off-types. Click here for the reasons tall off-types appear in spring wheat. Varieties that are notorious for off-types are Mayville, LCS Albany, and Rollag.

by Jochum Wiersma and Albert Sims

Interest in improving grain protein in hard red spring wheat (HRSW) with in-season applications of nitrogen (N) fertilizer may increase this year, since protein premiums and discounts are expected to be greater this year than last. Despite the late planting, the cool and wet weather has created a scenario where the crop may be a bit short on N to maximize grain protein.

There is an intuitive appeal to split apply N (N applied preplant and more N applied during the growing season) in HRSW since the crop takes up the majority of its N between jointing and flag leaf emergence. The practice of splitting the total N fertilizer gift in three or even four separate applications is commonplace in winter cereal production in the maritime regions of Europe, including the countries of Denmark, the Netherlands, the United Kingdom, and France. The objective of split N applications is to supply N when the crop needs it, improve N use efficiency, and consequently achieve maximum grain yield and/or grain protein with fewer N fertilizer inputs.

A Closer Look at Herbicide Rotation Restrictions

By Lizabeth Stahl, Extension Educator in Crops

What herbicides were applied earlier in the growing season can significantly influence the decision of what to do in fields or areas of a field where the original crop was flooded or hailed out.  Planting some kind of a crop can help reduce erosion potential as well as reduce the risk of fallow syndrome (see http://z.umn.edu/fallowsyndrome).  However, options can be limited if a herbicide used previously in the growing season has rotational or plant-back restrictions listed on the label.

John Lamb, Fabian Fernandez, and Daniel Kaiser
University of Minnesota Nutrient Management Team

Nitrogen is important for corn growth, and has been a recent concern. This year similar to many years has not had normal weather. Planting has been delayed by moist conditions and cold temperature. Now with the record rainfalls last weekend (May 30 through June 1, 2014), there are concerns that nitrogen has been lost to leaching or denitrification.

Heat Canker in Wheat, Barley, and Oats

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The last couple days the weather has given us some dry sunny weather with high winds. This has been great to have fields finally dry off and make strides with planting the crop. Unfortunately this also exposed young small grain seedlings to same conditions. The daytime heat at the soil surface has caused heat canker. The tender young tissue at the soil surface basically has been 'cooked' and this appears as a yellow band that is slightly constricted (Photo 1). As the leaf continues to grow, this yellow band (1/8 - 1/4") moves upward and away from the soil surface. If the hot and dry weather last for several days, repeated bands should become visible. The damage is nicely depicted on page 81 of the second edition of the Small Grains Field Guide. Because of the high winds, the tips of leaves may break off at the yellow band and give a field a very ragged appearance. Damage from heat canker is temporary and should not affect further growth and development.

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Photo 1 - Wheat seedlings with the yellow, constricted appearance symptomatic for heat canker (photo courtesy of Luke Steinberger)

Early Seasoning Yellowing of Wheat, Barley, and Oats.

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Reports of yellowing in small grains have started to reach us. There are several reasons why young wheat, barley, or oat plants have a pale green/yellow color. Some of the common reasons for early season yellowing are:

  • Nitrogen deficiency
  • Sulfur deficiency
  • Early tan spot infection
  • Herbicide injury

The nitrogen (N) deficiencies can readily be indentified as the symptoms are worst on the oldest leaves and start at the tip of the leaves, progressing towards the base as the deficiency gets worse. The causes of the N deficiencies are several, all which have common denominator, namely excess precipitation. Excessive rainfall causes:

  • Leaching
  • Denitrification
  • Inability of the plants to take up available N

Leaching is a potential problem in coarser textured soils. Saturated soils/standing water will cause both denitrification and inability to take up available N. Denitrification is a microbial process and slows down considerably as soil temperature decrease. According to Univ. of Illinois data (Hoeft, 2004), denitrification losses are 1-2% if soil temperatures are less than 55oF, 2-3% when soil temperatures are between 55 and 65oF, and 4 -5% once soil temperatures exceed 65oF. As soils are saturated, the plant's roots also are unable to take up N - even if available. Often the crop recovers quickly if the growing conditions improve and the excess water has drained.

If the N deficiency is severe, a supplemental application of N as either urea (46-0-0) or urea ammonium nitrate solution (28-0-0) can be advantageous. Research by George Rehm and Russ Severson in 2005 showed that 40 lbs of supplemental N at the 4 leaf stage yielded 7 bu/A extra over the untreated check.

Sulfur (S) deficiencies are generally found on coarser textured soils and can readily be identified as symptoms are worst on newest leaves and less on older growth. This is opposite to N deficiencies as can be explained by the difference in mobility of the element in the plant; N can be more readily be recycled from older growth and redirected to the younger leaves compared to S. Cool and dry conditions tend to make S more pronounced as less S becomes available from the breakdown of organic matter.

Cool conditions make some of the micro nutrients also less available to the plant. These symptoms are often first noted on the coarser textured soils. Again, George Rehm has chased this problem in the past and found that no single culprit was to blame. As soon as growing conditions improved, the symptomology would disappear.
Early season tan spot infection can also cause the young wheat and barley crop to turn a bright yellow. Especially young seedlings up to the 3 to 4 leaf are very sensitive to a toxin that is produced by the fungus. This yellowing affects the whole seedling. If tan spot is identified as the cause of the yellowing, an early season fungicide treatment is warranted. Additional details on how to effectively control early season tan spot can be found in a follow-up article by Dr. Madeleine Smith.

Although few if any acreage has received an herbicide to date, yellowing of the crop can also be caused by herbicides. Cool growing conditions make a number of our common small grain herbicides more prone to cause temporary injury. Especially the ACCase class of grass herbicides is more active with cool(er) growing conditions. This temporary yellowing will dissipate in one to two weeks after application with no effect on grain yield.

Hoeft, Robert. 2004. Predicting and Measuring Nitrogen Loss. University of Illinois Extension

By Lizabeth Stahl and Lisa Behnken, Extension Educators in Crops  

Access to results for many of the U of MN crops research trials conducted across the state has now become streamlined with the launch of the new, U of MN Extension Crops Research website.  This one-stop shop can be accessed through the U of MN Extension Crops webpage at www.extension.umn.edu/crops under "Research Reports".

The website contains results for small plot and on-farm crops research and demonstration trials conducted across Southern MN from 2003 to 2013.  You can also access research results for crops trials conducted at Research and Outreach Centers located across the state by clicking on the respective link.  Statewide results for weed science research can be accessed through the "Applied Weed Science" link, and results for the Minnesota hybrid and variety trials can be accessed through the "Minnesota Field Crops Variety Trials" link. 

The Research Reports webpage supplements U of MN Crops websites such as the "Corn", "Soybean", "Small Grains", "Forages", or "Sugarbeets" websites, or the "Nutrient Management", "Pest Management", "Ag Drainage", "Climate and Weather", and "Tillage" websites, where you can find research-based information and resources to help with specific crops-related decisions. 

Late Planting of Small Grains

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Wheat, barley, and oat are cool season annuals and are most productive when they grow and develop during cool weather. The yield potential of a crop is largely determined by the 6 leaf stage. Cool temperatures during this period are particularly important for the development of a high yield potential. For example, the number of tillers that ultimately produce grain at harvest declines as planting is delayed (Figure 1). The number of spikelets per spike is determined during the 4 to 5.5 leaf stage (Figure 2). Spikelet numbers are negatively correlated with temperature; spikelet numbers are greater when temperatures during the 4-5.5 leaf stages are cool.

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Figure 1 - The effect of planting date for on number of heads per square feet of hard spring wheat at harvest in Langdon, ND (data and graph courtesy of Terry Gregoire, Area Agronomist, NDSU).

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Figure 2 - The effect of maximum daily temperatures on the number of spikelets per spike that are initiated between the 4 and 5.5 leaf stage of spring wheat in Langdon, ND (data and graph courtesy of Terry Gregoire, Area Agronomist, NDSU).

Because of the expectation that average temperatures will be higher as we plant later, development of the crop will speed up too. The number of heat units required for a plant to move to the next phase of development will accumulate faster. This forces development along faster and causes the plant to have less time to grow. Plants end up with fewer tillers, smaller heads, and fewer and smaller kernels per head, cutting into our yields.

To improve the odds of high grain yields is to ensure that the tillering and head initiation phases occur during relatively cool temperatures is by planting early. Early planting is pivotal in this regard (Table 1)

Table 1 - The average seeding dates and last recommended seeding dates for small grains in Minnesota.
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Research has shown that, on average, yields decreased 1% per day when planting is delayed past the optimum planting date. Planting after the last possible date is not recommended because the odds that grain yield and quality (test weight) will be dramatically reduced due to heat stress.

You can partially offset this yield loss by increasing the seeding rate and ensuring that you have more main stems per unit area. The recommendation is to increase the seeding rate by 1 percent for every day after the optimum planting window.

The last possible date for planting is not chiseled in stone. The chances of a profitable crop just drop because of the anticipated weather and temperatures later during the growing season. Past the last possible date, you may want to consider an alternative crop, though economic reality might prevent this. If you stay with small grains past that date you will have to hope for a cool and dry summer. Point and case being the summer of 2013; weather conditions during grain fill last year proofed so favorable that, despite the late planting date, the State's average HRSW yield was the third highest ever reported. This feat was largely the result of the cooler nighttime temperatures. Figure 3 shows the difference in the minimum temperatures during the growing season in 2012 and 2013.

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Figure 3 - The difference in daily minimum temperatures during the growing seasons in 2012 and 2013 in Devils Lake, ND. Day 56 marks the approximate beginning of grain fill.

Crusting and Emergence Problems

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Last week's heavy rains have caused widespread crusting problems. Dr. David Franzen , NDSU Extension Soil Scientist, summarized the options available to you in an article more than a decade ago. It has been reprinted here as a refresher.

Crusting results from rains breaking down soil aggregates into particles that cement into hard layers at the soil surface when drying occurs rapidly. In soils that have not been seeded, the crust prevents further soil drying by sealing off the underlying soil from the air. The crust also reflects sunlight, in effect insulating the soil and maintaining cooler soil temperatures that further slow drying.

Crusts in unseeded fields can be broken by working the fields very shallow, no deeper than the depth of the crust, with such tools as a rotary hoe, a field cultivator with narrow shovels or spikes, or a rigid harrow. Breaking the crust will help dry the field more quickly and warm the soil. Some compaction will result from the extra trip over the field, but the benefits of the tillage should outweigh the negatives.

In seeded fields that received heavy rains after seeding and developed crusts, breaking the crusts may be crucial for good stand establishment and to avoid reseeding. A rotary hoe is the best tool for breaking a crust. A spring-tooth harrow with the teeth set straight down instead of slanted back can sometimes be used. The circular motion of harrow teeth set in this fashion can be very effective at breaking a crust enough for young seedlings to emerge. A heavy rigid harrow should be avoided as too much soil movement may expose seedling roots. If neither of these tools is available, running over the field with and empty double disc drill will also break the crust.

The goal of any crust-breaking trip is to crack the crust into small pieces and move them around slightly to let air and light into the soil below. Seedlings trapped under a crust will try to grow and elongate below the crust until they run out of stored energy from the seed. The cooler the weather, the longer the seedling can survive, unless a seedling disease infects it. The warmer the temperature, the faster the seedling will try to grow and the sooner it will run out of energy. It is important to deal with crusts soon after they form.

With any crust-breaking method, some stand damage is likely. However, compared to the damage a crust can do, the damage done while breaking crust is usually much less than the crust itself causes.

Evaluating Winter Wheat Plant Stands

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One of the hardest decisions with growing winter wheat is evaluating the amount of winter kill and making the decision whether to keep a stand. Winter wheat is planted in the fall and develops in the spring during relatively ideal conditions for tiller development. Therefore the optimum plant stands of winter wheat can be less than that of spring wheat. A stand of 900,000 - 1,000,000 plants/acre or 21 - 23 plants/ft2 will be enough to maximize grain yield.

Some winter kill is to be expected in Minnesota. This past winter was cold even by Minnesota standards. The extreme cold, combined with little snow cover in parts of the state, and that the fact some of winter wheat was planted on prevent plant acres that had little or no standing stubble to collect the limited snow that fell, means that winter kill is very likely this year. Roots are generally less winter hardy than crowns and regrowth may be very slow, even if roots and shoots appear dead.

The very cool and wet weather to date has meant that fields have been very slow to green up and have just started to put on new leaves and tillers. This past week was probably the first time that evaluating surviving plant density was fairly straightforward. The problem that remains, however, is that winter survival in all likelihood will variable within a field and depending on topography (windblown hilltops having less stand than protected areas of the field). If stands are reduced uniformly across the field, stands of 17 plants/ft2 can still produce near maximum grain yields. Even stands as low as 11 plants/ft2 can still produce a 40 bu/A yield.

Given the lateness of the spring and the likelihood that anything else that is planted will be planted later than optimum creates another incentive to stick with a less than ideal stand of winter wheat. Consider interseeding spring wheat to fill large gaps but be prepared for the fact that spring wheat matures later than winter wheat so harvest will be problematic. Furthermore, mixing wheat classes can cause problems at the elevator. Planting winter wheat into large gaps can also be an option. Winter wheat planted in the spring will not vernalize so it will not produce a head (or there will be fewer late heads), but will provide ground cover until harvest.

By: Mike Boersma, Extension Educator, Murray and Pipestone counties


The University of Minnesota Winter Crops Day and Small Grains Program is a great opportunity to hear the latest University-based research and information about corn, soybean, and small grain production. Whether you are a producer or an Ag professional who works with producers, this program is sure to provide relevant and practical information to help you be successful. The morning will focus on various aspects of corn and soybean production while the afternoon will focus on small grain production in southern Minnesota. The program will be held at the Slayton Pizza Ranch on Tuesday, February 25th. Registration will begin at 8:30 am, with the program running from 9:00 am to 4:00 pm.

Larry D. Jacobson, Extension Agricultural Engineer, U of M Extension

With the harvest season fast approaching, the application of stored manure from animal facilities on the harvested fields will soon follow. This year, pork producers need to be aware of the risk of spreading Porcine Epidemic Diarrhea (PED) through equipment used to pump and land apply manure from all farms but especially those with pigs exhibiting clinical signs of the disease. PED can be spread through oral-fecal contact, manure contaminated boots, clothing, birds and wildlife, transport trailers and other equipment.

PED is a viral enteric swine ONLY disease with clinical symptoms of diarrhea, fever, vomiting, and death (age dependent). PED was first detected in the United States this spring and as of the first of September the disease had been confirmed on more than 500 swine herds in the United States. Spread of the virus continues, and it is both a good animal husbandry practice and a good neighbor policy for all pork farmers with pigs exhibiting clinical signs of PED to obtain a confirmed diagnosis and immediately establish enhanced biosecurity practices to avoid spreading the virus within their own animals and (or) to neighboring swine herds.

Because many pork producers hire commercial manure applicators to pump and land apply their manure from a farm's storage pits, tanks, and/or basins, their equipment can easily spread this virus from infected farms (barns) to uninfected farms (barns). In response to this urgent concern, the National Pork Board (NPB) along with several midwestern universities (Michigan State, Iowa State, and Minnesota) have just released a one page fact sheet listing the biosecurity recommendations that commercial manure haulers should follow to reduce the risk of spreading this virus.

The fact sheet emphasizes the need for the manure applicator to communicate closely with the pork producers when pumping manure on a farm to reduce the risk of transferring this virus by manure handling equipment either from or to the farm.

The fact sheet is available here: NPB's Biosecure Manure Pumping Protocols for PED Control. Additional PEDV resources are available at http://www.pork.org/Research/4316/PEDVResources.aspx.

The Art of Swathing

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Swathing or windrowing of wheat, barley and oats were, at one time, the default operations that signaled the beginning of harvest. The primary purpose of swathing is to speed up and even out the dry down of the crop. Swathing always posed a risk as grain in the swath is more prone to preharvest sprouting if threshing is delayed due to adverse weather

Therefore, most wheat and barley is now straight cut in large part because modern varieties allow for it. Preharvest applications of glyphosate have further reduced need to swath wheat. In oats swathing remains more common place.

Swathing is becoming, however, something of a lost art. First, you have to decide when the crop is ready to be swath. The optimum time to swath is when the crop has reached physiological maturity. This is the same time to consider the application glyphosate. This is the point in the development when the crop has reached its maximum dry weight and the grainfill period has come to an end. Moisture content of the grain will vary but the ranges from 30 to 40 percent. In the absence of a moisture meter, there are other cues that signal the crop has reached physiological maturity. One of the easiest is to look at the color of the uppermost internode, or peduncle. The upper most portion of the peduncle, just below the spike or panicle, will have turned very light green to yellow when the crop reaches physiological maturity. There still may be some green in the canopy below or in the glumes but the least mature kernels will no green left in them, when threshed out by hand, .

Swathing before the crop reaches physiological maturity will result in yield and test weight losses and green kernels in the harvested grains. The losses get progressively worse the earlier you cut the crop. Research at NDSU in spring wheat and durum showed that swathing the grain at 45% moisture caused a 1 to 2 lb reduction in test weight and about a 10% reduction in grain yield. Swathing after physiological maturity increases the risk of shattering and will equally cause yield losses but no losses in grain quality. Shattering losses can be reduced by swathing in the early morning or late evening when some dew is present in the crop.

Small Grains Disease Update 07-18-13

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The grain fill is rapidly progressing towards physiological maturity in both spring and winter wheat across the State. Actually, the first winter wheat in West Central Minnesota was reportedly harvested today. The scouts continue to predominantly fin the tanspot/Septoria complex of leaf diseases and BYDV. Incidence of leaf rust remains low while no stem or stripe rust was found to date.

This year marks the 20th anniversary of the great scab epidemic of 1993 and. Although we have made considerable progress towards controlling the disease, by now means have we eradicated or silenced the disease. Winter wheat trials in LeCenter and Crookston are showing a fair amount of FHB as do the some of the earliest spring wheat fields. It is too early to tell whether we have widespread problems this growing season but that the disease is here again this year is pretty clear.

Therefore, assess the damage caused by FHB now and prepare for harvest accordingly. If you have little to no affected spikelets 10 to 14 days after anthesis you escaped the worst and can probably harvest the way you always do. If, however, you see 10% more of the spikelets affected, you need to make sure that you: 1) increase the fan speed to attempt to remove as much of the tombstone kernels as possible, 2) store the harvested grain separately as much as possible. The idea is to reduce the DON toxin levels as much as possible in the harvested grain and quarantine grain that may have elevated levels of DON as to not contaminate otherwise sound grain from other fields/varieties.

Bruce Potter in Lamberton reported on flights of armyworm moths a few weeks back. Doug Holen confirmed armyworm damage in lodged grain earlier today in the Fergus Falls area that included leaf and head clipping. Armyworms are dark green to light brown worms that can get up to 1.5" inches in length. Scouting for armyworms requires some effort as they are largely inactive during the day. Look for the small fecal pellets on top of the soil and move debris and small clumps of soil around to find the larvae curled up underneath. A treatment to control armyworm is recommended if 4 to 5 larvae per square foot can be found across much of the field. Reduce this threshold if head clipping occurs.

Small Grains Disease Update 07-18-13

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The grain fill is rapidly progressing towards physiological maturity in both spring and winter wheat across the State. Actually, the first winter wheat in West Central Minnesota was reportedly harvested today. The scouts continue to predominantly fin the tanspot/Septoria complex of leaf diseases and BYDV. Incidence of leaf rust remains low while no stem or stripe rust was found to date.

This year marks the 20th anniversary of the great scab epidemic of 1993 and. Although we have made considerable progress towards controlling the disease, by now means have we eradicated or silenced the disease. Winter wheat trials in LeCenter and Crookston are showing a fair amount of FHB as do the some of the earliest spring wheat fields. It is too early to tell whether we have widespread problems this growing season but that the disease is here again this year is pretty clear.

Therefore, assess the damage caused by FHB now and prepare for harvest accordingly. If you have little to no affected spikelets 10 to 14 days after anthesis you escaped the worst and can probably harvest the way you always do. If, however, you see 10% more of the spikelets affected, you need to make sure that you: 1) increase the fan speed to attempt to remove as much of the tombstone kernels as possible, 2) store the harvested grain separately as much as possible. The idea is to reduce the DON toxin levels as much as possible in the harvested grain and quarantine grain that may have elevated levels of DON as to not contaminate otherwise sound grain from other fields/varieties.

Bruce Potter in Lamberton reported on flights of armyworm moths a few weeks back. Doug Holen confirmed armyworm damage in lodged grain earlier today in the Fergus Falls area that included leaf and head clipping. Armyworms are dark green to light brown worms that can get up to 1.5" inches in length. Scouting for armyworms requires some effort as they are largely inactive during the day. Look for the small fecal pellets on top of the soil and move debris and small clumps of soil around to find the larvae curled up underneath. A treatment to control armyworm is recommended if 4 to 5 larvae per square foot can be found across much of the field. Reduce this threshold if head clipping occurs.

By Lizabeth Stahl and Jill Sackett, Extension Educators

 

The challenging spring of 2013 resulted in wide-spread planting delays across the state and a significant amount of acres that remain unplanted at this time.  If the decision has been made to take the "prevented planting" option for insurance purposes, the question remains about what to do with these acres.  Leaving the ground bare greatly increases the risk of not only soil erosion, but also the risk of "Fallow Syndrome" the following year. 

By John Wiersma
Agronomist
Northwest Research and Outreach Center

High pH, highly calcareous soils, common in western Minnesota, restrict the availability of soil Fe needed for optimum soybean growth and yield. On such soils, the amount of Fe fertilizer applied must surpass a threshold before there is sufficient available Fe in the soil solution to induce a positive growth response. Only a limited number of management tactics designed to improve the availability of Fe have been studied with soybean. These include variety selection, seeding density, seed-applied or in-furrow materials, and foliar treatments.

Daniel Kaiser
Extension Soil Fertility Specialist

I know there are still questions on the application of sulfur for soybean.  Between me and a number of other researchers in Minnesota, we have been working on a number of projects focusing on sulfur management on corn, soybean, and spring wheat.  Recently the soybean research has been fully summarized so I want to take a minute or two to highlight some of the findings to outline where we are at with the current guidelines for fertilizer management on soybean.

Planting Window for Small Grains Already Closing

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While nearly all the small grains were seeded in Minnesota by this date in 2012, this spring is a different story. The unseasonably cold temperatures and relentless snow fall is setting us up for a (very) late spring. This will mean that, already, the planting window for small grains is closing for parts of the state. Understand that you can still plant spring wheat, barley, and oats after the last recommended date but that the chances to have good, competitive grain yields and quality are greatly reduced.

Check out this post from 2008 to understand how and why the planting window for wheat, barley and oats is what it.

Daniel Kaiser
Extension Soil Fertility Specialist

A few questions arose over the winter as to options for spring applied nitrogen for small grains in areas where fall application was not possible.  One option that was questioned was increasing application rates with the air seeder.  While this does present increased risk, with spring approaching I wanted to take the opportunity to highlight some resources available for helping make decisions on what to apply.  Application with the air seeder allows for more options due to a wide range of seedbed utilized with the various seed spread patters available. 

Soil Testing For K

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By Daniel Kaiser
Extension Soil Fertility Specialist


With spring finally approaching it is a good time to address some questions on soil testing that came up of the winter concerning testing soils in a field moist state versus the standard dried samples that are run through soil testing labs.  First I would like to make it clear that the issue of drying of a soil sample mainly pertains to potassium.  Most other tests routinely run through the lab are not affected by drying of the sample.  The reason why potassium is different is due to its chemistry in the soil.  We currently have finished the second year of potassium studies looking at both testing methods but will be continuing this work for the foreseeable future to gain a better understanding of what is going on within the soil.

U of MN Field Crop Trials Bulletin Available

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By Lizabeth Stahl

The University of MN Field Crop Trials Bulletin is now available in print and electronic forms. The new publication, dated January 2013, provides results from U of MN trials conducted in 2012 across the state. The varieties tested are from both public and private breeding programs and include U of MN developed forage, grain, and oilseed crop varieties.

Tips for Planting Winter Wheat Late

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The unusually warm summer this year now means that there are many acres that have been harvested that potentially could be planted to winter wheat. It appears that the lack of rainfall could be a deterrent to winter wheat planting, at least to getting it planted during an optimum period. Our current recommendations are to plant winter wheat in the northern half of Minnesota by the middle of September and the rest of the state by October 1st. Unfortunately, there does not appear to be any rain in the immediate forecast. Planting into dry soil and waiting for rain is a viable option. In this scenario, put the seed about an inch deep so that it will be able to emerge quickly once rainfall is received. Though seeds that just begin the germination process will vernalize (meet the necessary cold requirement to produce a spike in the summer), a much larger seedling typically has a better chance of overwintering and being more productive. In the last three years of our research, the early planted treatments have always been more productive than those planted later than optimal, though the difference was not always large, depending on the year and the variety grown. If the warm weather we are currently experiencing spills over into the October, however, there should be ample time to produce a productive seedling, even if rains delay a week or two more.

The following are some guidelines to consider when planting winter wheat late or in conditions where it may germinate and emerge late:

  • Increase your seeding rate by about 150,000 to 200,000 seeds per acre. There is no advantage to seeding more than 1.8 million seeds per acre, however.
  • Select more winter hardy varieties. Late planted seedlings will be small as winter approaches and will be more prone to winter injury, particularly if there is little snow cover this winter. A winter hardy variety will help reduce the risk of winter injury and be more productive when conditions are conducive to winter injury. Check the most recent University of Minnesota Variety Trials Bulletin for information about the winter hardiness of varieties currently available for planting.
  • Plant into standing stubble if you have a choice. Standing stubble will catch snow, if there is any, and help insulate the crop during the winter. Since late plantings are more prone to winter injury, management practices that increase the likelihood of warmer soil temperatures will improve the chance of winter survival.
  • Add some phosphorous with the seed. This is especially true if your soil test for P is low. P helps to develop strong roots and crown tissue which will aid in the overwintering processes. The rate of P applied, should be limited by the amount of N that is applied with the P. With narrow rows, nitrogen should not exceed about 15 lbs/acre with the seed, particularly in these dry conditions. With wider rows, be more conservative with the rate.
  • Consider treating your seed with fungicides and possibly an insecticide. Since the seed may lay in the soil for an extended period before germination, a fungicide applied to the seed will help protect it from diseases and an insecticide will be beneficial especially if wireworms are likely to be present.

Small Grains DIsease Update

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Temperatures are set to be high again this week with maximum temperatures forecasted from the high 80s to mid 90s. Humidity will be lower than we have seen in the past week. Most of the wheat crop is now in the soft to hard dough stage of development.
With the warmer weather, stripe rust is finally entering the resting stage of its life cycle evident as black telial pustules on leaves. Leaf rust incidence is moving North and West through the state with the highest incidences (up to 100%) and severities (up to 30%) being reported in Otter Tail county.
Incidence of tan spot is on the increase as well - in some cases 100%,of affected - with low to moderate severity. This trend is likely to continue in the central and eastern parts of the state over the next few days.
Risk of leaf rust in the central and eastern part of the state will trend much higher in the next couple of days. The risk for tan spot remains high throughout the state.
Scab risk remains moderate to high in the north west of the state. Initial reports of scab infections have been confirmed, especially in the most northwestern portion of the State. This is the same area for which the risk model had shown a moderate risk for FHB 2 to 3 weeks ago. Incidence and severity are low at this point.

Small Grains Disease Update

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07/10/2012

Temperatures are set to be slightly cooler this week than last, and expected to stay in the low to mid 80s. Humidity will be lower than we have seen in the past week. Most of the wheat crop is now in the late milk early dough stage of development.

Stripe rust is still prevalent across the state. However weather conditions are now becoming favorable for development of leaf rust which is evident in the south and west of the state with severity ranging from moderate to severe. Sibley county being the worst affected at present. Septoria diseases have progressed with 100% of some fields affected with moderate to high severity.

Risk of leaf rust in the central and eastern part of the state will trend much higher in the next couple of days . The risk for tan spot remains high throughout the state. Scab risk remains moderate to high in the north west of the state.

Reports of fields with a unusual amount of dead heads with little or no grain have been reaching us. Incidences as high as 15-20% have been reported. We are sampling some of the worst fields to determine the exact cause or causes and will share those results as they become available.

Small Grains Disease Update

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Weather conditions have been getting steadily warmer over the last week, routinely in the mid-80s° F. This trend is set to continue over the next week with temperatures reaching the low 90s° F. This unusually dry and warm weather is having a direct impact on the range and severity of diseases and plants reactions to other stresses such as herbicide drift and drought. With the majority of wheat in the end of milk and into the early dough stage, many plants are clearly showing evidence of heat stress. This heat stress is exacerbating other diseases that are not normally prevalent.

Stripe rust is still very evident across the state with high severity on spring and winter wheat in to the mid canopy. A number of fungicides will give good control of stripe rust provided they are applied before symptoms are evident on the flag leaf. Fungicide application will not cure already visible or latent infections. Although the warm temperatures will slow stripe rust development, cooler night time temperatures and the chance of stormy precipitation, will allow this disease to continue. If generic Folicur, Prosaro or Caramba were already applied at Feekes 10.51 to suppress scab, you can expect sufficient control for the remainder of the growing season for stripe rust.

Septoria species are also becoming prevalent in the west central portion of the state with low - mid severity on 20-50% in the fields scouted. Evidence of wheat stem maggot is now appearing in the south-west of the state. Typical symptoms of damage caused by this insect are white or blasted heads which will produce no grain, while the rest of the plants looks normal. The head can easily be pulled from the plant to reveal the feeding damage.

Because of the weather, the risk of scab is likely to be very low over the next week. These same conditions are more conducive to stem rust and leaf rust may become more evident, especially in the southern part of the state.

Tall Off Types in Wheat.

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A fair number of spring wheat fields appear to be quite variable in plant height this season. Obviously varying degrees of drought stress can create height differences that are, in some instances rather striking ( Photo 1). Differences in height, however, are more interspersed and without clear delineations and/or transitions as is the case in photo 1, it is probably not drought stress per se but one of three things:

  • a variety blend
  • a variety that is segregating for plant height
  • a variety that suffers from a genetics anomaly that results in a chromosome being lost across generations.
The first cause is rather straightforward; if during anytime in the previous generations seed of another variety inadvertently has been comingled with the variety you think you have, you will get mixtures of varieties. This happens more often than probably any of us want to admit and it's the reason why sanitation (i.e. cleaning equipment and bins) is so important to maintain variety purity.

The second reason for differences in plant height is much less common but the extreme growing conditions we are experiencing this year can bring some differences in plant height that previously had gone unnoticed. Without going into too much detail, you have to understand that most varieties that are released are actually number of sister lines derived from the same cross that are nearly identical. These lines only differ for a few percentage point of the total number of genes, most of which will go unnoticed. After all, to be recognized the Plant Variety Protection Act requires that the variety meets certain minimum for distinctness, uniformity, and stability or DUS requirements for wheat. Breeders will generally select a number of sister lines that phenotypically are hard to distinguish from another in an environment that shows differences well. Dr. Jim Anderson, for example, will often do this work in the winter nursery in Arizona to detect even the slightest of difference in plant height and/or maturity. The extreme conditions we are encountering this season may, however, trigger some differences that previously had gone unnoticed.

The third reason is related to a problem that is particularly unique to wheat. It can create challenges for the DUS requirements, especially if the enforcement of the PVP is strict as is the case in many European countries. With the introduction of the semi-dwarf genes, the breeders quickly noticed that in certain lines and genetic backgrounds a number of tall plants would appear at a low frequency from one generation to the next generation (Photo 2). Subsequent research showed that in certain wheat varieties up to 6% of the time something goes during the formation of the pollen grains in certain g. This, in turn, leads to some 1% of the next generation to be so-called aneuploids, meaning having an individual progeny with one of more chromosomes missing or extra. Monosomic deletions, i.e. plants missing one chromosome, are most commonly encountered. Most often you will never see a difference, except in the case of semi-dwarf wheat varieties.

The odds that a chromosome gets lost in the shuffle that is called meiosis during the formation of pollen grain appears to be equal for all 48 chromosomes that make up wheat. Consequently, ever so often the one of the two chromosomes that carries the semi dwarf genes goes missing. This in turn results in half the reduction in height compared to the genetically equivalent variety without the semi-dwarf genes (another way to think about this is that only one instead of two doses of a medicine are given to shorten the height of the patience). The frequency of this phenomenon appears to be rather constant in certain background and varieties like Vance were notorious for getting 'dirty' over time.

A nice article that describes this phenomenon in more detail can be found here. An interesting experiment to do is to safe some seed of these tall off-types and grows them out next year. Half the plants derived from these tall off-types should revert back to the original variety, the other half of the plant will be the taller off-type again.

Small Grains Disease Update

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While a 11-plus inch deluge made for national headlines in Duluth, much smaller but timely rains have helped stave a worsening of the drought stress in parts of northwest Minnesota. Drought stress is pretty evident is many fields as evidenced by differences in plant height across the field. On June 19, the majority of northwest Minnesota is still rated to be in a moderate drought while a large portion of west central Minnesota is still considered abnormally dry. Timely rains will be needed to allow grainfill not to be impacted by drought as the crop needs nearly a 0.25 inch of water daily at the beginning of grainfill.

Most spring wheat is passed anthesis and in to the grainfill period. Reports indicate that many of you applied a fungicide to protect against foliar diseases and protect against Fusarium Head Blight. The University of Minnesota scouts continue to report that BYDV, stripe rust, tan spot and Septoria spot blotch are the most commonly found diseases. Severe BYDV is being reported from the west and central areas of the state, with yellowing and sever stunting in many cases due to the early season infection this year. Cool wet conditions have seen the increase of Septoria spot blotch in the north west of the state becoming prevalent on the lower canopy. With low humidity and little rain forecast the disease is likely to be slow moving into the upper canopy. Stripe rust is present throughout the state to varying degrees. Faller being one of the most affected varieties with infection reaching mid to upper canopy in some fields, but some stripe rust has also been found on Vantage.

The risk of FHB as predicted by the disease forecast models indicated relatively low risk for most of Minnesota for much of the past 7 days. The exception being much of Kittson county in the extreme northwest corner of the State. The weather outlook for the next 3 to 5 days suggests that the risk is likely waning.

A few calls have come in about powdery mildew having been detected in the lower canopy despite an application of a fungicide at anthesis. Understand that most if not all of the spray volume was deposited on the head and the upper canopy. Consequently it will not give good control of powdery mildew despite the fact that tebuconazole and Prosaro give good control of powdery mildew. The warmer daytime temperatures should really slow down these infections. Powdery mildew will turn from gray white to a tan color when it gets too hot for it to flourish.

The first case of crown rust has been reported on oats in Renville County.

Small Grains Disease Update

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06/14/2012

The spring wheat in many parts of the state is now fully headed or pretty close to it. The drought stress has been partially abetted with some timely rains over the weekend. Yield potential, however, of the most drought stricken fields has been greatly reduced as tillers and lower leaves were aborted. This is very visible as the canopy opened up. Some of the worst field will likely not yield much over 35 to 40 bushels.

As far as diseases are concerned, these are some of our own observations and those of the scouts that are paid for through a grant of the Minnesota Wheat Research & Promotion Council. Tan spot is still the most prevalent disease, closely followed by stripe rust. Both diseases have progressed to the middle of the canopy, particularly on more susceptible varieties, as is the case for Faller and stripe rust

BYDV like symptomology can be readily found in barley, particular in the southern half of the state. Disconcerting in these cases is the high incidence and the severity; very seldom, if ever, have we seen such a widespread infection across fields, and the severe stunting. Fields have actually been abandoned and replanted with soybeans in the past week.

Now is the time to scout the fields to assess yield potential and the presence of any foliar diseases such as tan spot and leaf or stripe rust. With the increase in precipitation, disease risk models have, and will likely continue to trend higher, especially for the foliar diseases such as tan spot and stripe rust.

The decision to apply a fungicide at Feekes 10.51 will not be easy this year. Given the weather forecast for the next 5 to 7 days, we don't expect the risk models for FHB to increase dramatically. The decision therefore will hinge as much on the presence of foliar diseases as on the risk for FHB. The lower yield potential further complicates the matter.

Small Grains Disease Update

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The Minnesota Wheat Research and Promotion Council funded a disease survey in small grains in 2012. This is a summary of what the scouts have found in the past few days:

The winter wheat is mostly at or just past anthesis is looking very good overall. The spring wheat is not far behind and is more variable. Drought stress is evident in the central and northern portions of the Red River Valley with the area around Crookston being the hardest hit by drought. Available soil moisture at the NWROC is between ~ 2.7 to 3.3 inches in the top 5 ft of three soils series that were sampled last week (or less than 25% of field capacity), with less than 0.5 inch in the top two feet of two of the three samples.

As far as diseases is concerned:

1) Scattered incidence of powdery mildew in winter wheat throughout the state. Incidence and severity generally pretty low except for one particular field where is was quite high.

2) Tan spot can pretty readily found in the middle and lower portions of the canopy of winter wheat and initial infections are starting to show in spring wheat. Incidence in spring wheat is very low. This is likely a function of the fact that most growers now routinely use half a labeled rate of a fungicide at F5 in a tank mix combination with the weed control program. Likewise initial infections of net blotch in barley and Septoria spot blotch in spring wheat can be found.

3) BYDV like symptomology can be readily found in oat and winter wheat across the state. Foci tend to be small (couple of plants) to medium sized (several feet in diameter) circular patches throughout the field. Aphids (bird cherry oat and English grain) can be found but are generally not at threshold. Some stunting evident, something we rarely see.

4) No confirmed cases of aster yellows to date, but the first few cases have been submitted for diagnosis.

5) Stripe rust is now common in the southern portion of the state with incidence nearing 100% in 'Faller' spring wheat (Faller is readily identified because of the rather distinct purple auricles - click here for more details). Severity is approaching 10% on the penultimate and/or flag leaf is some fields.

6) Leaf rust has been confirmed is a spring wheat field near Barrett, MN (west central MN). The variety was unknown but the incidence was low. The reaction type, however, was S.


There is a fair amount of herbicide injury also showing up in spring wheat that may be mistaken for disease symptoms. The drought stress and a couple of cool nights following the herbicide application is causing this increase in the incidence and severity of the herbicide injury.

For high yields, small grains need 14 to 17 inches of water depending on weather conditions and length of growing season. The water used for optimum growth is a combination of stored soil moisture, rain and irrigation. Small grains require about six inches of water as a threshold for grain yield. Each additional inch of water will provide four to five bushels per acre. In deep well-drained soils, the roots of small grains will extract water to a depth of three feet. Small grains are most sensitive to water stress in the boot to flowering stage of growth.

While many parts of Minnesota have come out of the drought, northwest Minnesota is still very dry. As of May 29th, the US Drought Monitor classified this area of the state as either abnormally dry or in a moderate drought. Last week's available soil moisture was less than one inch in the top 3 ft of two soils cores that were taken at the NWROC and less than two inches in the top 3 ft of a third core.

During the peak water use period, small grains can use up to 0.30 inches per day depending on air temperature and cloud cover. Daily crop water use - often called evapotranspiration or ET - depends on plant development and local weather conditions. Small grain water use will generally peak between heading and early dough stage. Daily ET estimates in the tables are based on long term average solar radiation and cloud cover. Daily ET estimates in northwestern Minnesota may be 5 to 10 percent greater than estimates found in Table 1 for central Minnesota because there is a greater chance for clearer and cloud free sky.

Real-time daily crop ET estimations during the growing season can be obtained from the Internet: For North Dakota go to here and for Minnesota go to here.

Small grains are susceptible to fungal infections. Most small grains are irrigated with center pivots; therefore it is better to apply at least an inch of water per irrigation rather than more frequent small applications. Wheat and barley are particularly susceptible to Fusarium head blight (FHB) prior to and during flowering. Irrigation during this period should be avoided if possible thus root zone water should be brought to a high level prior to flowering.

For detailed instructions on how to apply the daily crop water use estimations from these tables within an irrigation scheduling program review the Irrigation Scheduling Checkbook Method from the University of Minnesota Extension.

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FREEZE INJURY IN SMALL GRAINS

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The last two mornings thermometers have dipped below 32oF in many places across Northwest Minnesota. Unlike the freezing temperatures we endured in April, these lows may have actually caused some damage as most fields are now at or past the jointing stage. Kansas State University has published an excellent bulletin about freeze injury in wheat that describes in detail what the damage looks like and what the yield impact can be. Simply follow this link: Spring Freeze Injury to Kansas Wheat

Understand that any freeze injury is probably localized to sheltered and low lying areas. You should also now that damage to the growing point may not be evident immediately. Leaf tissue that is damaged should show symptoms after a day or two.

Small Grains Disease Update

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05/31/2012

Winter and the earliest spring wheat fields are heading across the State. While producers in the southern half of the State comment that their winter and spring wheat has never looked this good, the northwest part of the State suffered enough drought stress to impact the yield potential of the spring and winter wheat crops. The drought and last week's heat caused tillers to be aborted and crop phenology to advance rapidly, with some field moving from jointing to having the flag leaf fully emerged in just over a week. A few initial counts of the number spikelets per spike were disappointing.

There are confirmed reports of stripe rust across the state but there are no confirmed cases of leaf rust to date. More details scouting reports will be available as of next Monday morning.

Now is the time to scout the fields to assess yield potential and the presence of any foliar diseases such as tan spot and leaf or stripe rust. Keep an eye on the weather forecast and the disease forecasting models to determine the risk for Fusarium head blight to decide whether an application at anthesis is warranted.

Potassium and Dry Soils

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Daniel Kaiser and Jochum Wiersma
University of Minnesota Extension

Weather conditions have been extremely variable around the state of Minnesota this year. While some areas have experienced near record rainfalls others have still been in the midst of a drought. These differences have brought some interesting questions regarding management of potassium and soil testing in the midst of dry soil conditions.

High populations of Aster Leafhopper (also called 6-spotted Leafhopper) have been reported in small grains over the past couple of weeks. Starting in the south but now spreading to northern MN and ND. Aster Leafhoppers are greyish leafhoppers; the adults have clear wings and 6 spots between the compound eyes (Figure 1). Other than their coloration, the adults and nymphs both very much resemble potato leafhopper. The leafhopper uses it's piercing sucking mouthparts to feed on the plant's sap. The damage caused by Aster Leafhopper feeding is more localized than that produced by potato leafhopper. Feeding may produce localized necrosis or stippling (Figure 2), however, damage is much less than that caused by the Potato Leafhopper.
While they may overwinter as eggs in parts of MN, the sudden arrival of large populations of adults, together with the lack of nymphs present, indicates they arrived here from somewhere else. Like many other snowbirds in this area, part of the northern plain's populations overwinter somewhere warmer and return to the north when the weather once again becomes bearable! Once active in the region, Aster Leafhoppers feed on a wide variety of grass and broadleaf plants, crop and non-crop alike. Adults may move between host plants and follow what's green and available.
Disease Vectors - These insects can be economically important in wheat when they vector of Aster Yellows (AY). Feeding injury of aster leafhoppers is less important than disease vectoring. AY has a very wide host range and causes economic losses in several vegetables and ornamentals. If you have seen purple coneflowers with green distorted flowers, you have seen the aster yellows plant disease. Aster yellows is caused be a phytoplasm; an organism similar to a bacterium but without cell walls. When AY infects wheat, it produces symptoms very similar to Barley Yellow Dwarf Virus (BYDV).
Research has shown that heavy infections of AY can cause yield loss in susceptible wheat varieties. There are anecdotal observations from wheat varietal plots in northern Minnesota, which indicate that AY symptoms may be more severe, or that the disease is aggravated under wet conditions.
Aster leafhoppers acquire the phytoplasm by feeding on an AY infected plant for a minimum of 30 minutes. Acquisition of the phytoplasm increases with longer feeding times. The AY phytoplasm requires another two weeks, to incubate within the aster leafhopper before the leafhopper can transmit the disease to new plants. Consequently, immigrating aster leafhoppers, arriving already infectious for AY, are more likely to vector the disease into fields than the smaller overwintering populations which have to acquire and incubate the phytoplasm before they can infect plants. However, once it acquires the phytoplasm, a leafhopper remains infectious for an extended period of time. Although the acquisition phase may be long, it takes a very short feeding period by the leafhopper to transmit the disease to uninfected plants. Generally speaking, the more disease vectors that are present, the greater the potential for that disease to spread.
Feeding Damage - Other than vectoring AY, there is little data on the impact of very high levels of aster leafhoppers. In most years the populations of aster leafhoppers are lower and their feeding injury has little or no impact on wheat yield. We have no data indicating if this is the case with very high populations of aster leafhoppers such as we are seeing this year.
Management -Unfortunately, there is no clear cut answer as to whether treatment of an individual field is warranted; we have no action thresholds for this insect as it is rarely a problem (the only mention we can find of treatable levels is from a 1935 paper that refers to clouds of leafhoppers at one's feet). There are a number of factors to be considered before making individual decisions.


  • High numbers of vectors increase the chances of disease spread

  • There is little data indicating that direct feeding damage causes wheat yield losses. There is no treatment threshold (clouds not being a very useful term).

  • The rapid transmission of AY may mean that fields with heavy populations of aster leafhoppers may contain plants already infected with the disease, so killing aster leafhoppers to avoid AY may not be effective.

  • There's not yet a canopy, plants are small, rapidly adding new leaves and have maximum exposure to wind, sun and moisture, meaning insecticide residual is going to be shorter than later in the season. So there's no guarantee that treated fields may not become re-infested with aster leafhoppers.

  • Treating with a broad spectrum insecticide will kill beneficial organisms and may lead to higher aphid populations and BYDV. Bird-cherry oat aphids are already present in southern MN and BYDV is a more serious threat to wheat yield than AY. Populations of aphids in the field would favor treating the field and influence the insecticide used.

  • Both Aster Yellows and Barley Yellow Dwarf must be transmitted by insects (aster leafhoppers and aphids respectively). If you see discoloration in the absence of these insects, it isn't AY or BYDV, look for some other cause!


The bottom line is this will have to be an individual's decision and is a field by field situation, please use the facts that we've mentioned above and make the best decision for your production system.
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The 2012 growing season is well under way. The spring planting progress has been at a record pace, a consequence of a very dry fall and winter and a very warm March. Winter wheat has very little winter injury and stands are generally very good.

The winter wheat crop is at or near jointing and some of the earliest spring wheat fields are not far behind. This means that it is time to start scouting for early season tan spot.

To aid in your decision whether a fungicide is needed to control early seaon tan spot you can go to http://mawg.cropdisease.com to evaluate the risk that conditions are favorable for tan spot to develop. Make sure to select the model for tan spot in the left hand model.

An overview article of control of early season tan spot can be found here:
http://blog.lib.umn.edu/efans/cropnews/2010/05/early-season-tan-spot.html.

Be aware that tank mixing fungicide with certain herbicides can result in temporary crop injury. See here for details here http://www.plantmanagementnetwork.org/sub/cm/research/2011/mixing/ and http://blog.lib.umn.edu/efans/cropnews/2011/06/early-season-tan-spot-and-risk.html

When is Early too Early?

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The record breaking temperatures of the past week make it feel more like the middle of May than the middle of March. Obviously, as the fields look ready, the question arises whether this early is too early. With the very late start of 2010 and the disappointing wheat and barley yields that followed still fresh in memory, everyone understands that early planting is paramount. What are the risks of planting too early? Is there such a thing as too early for seeding wheat and other cool season grasses?
Spring wheat (and spring barley and oats) will start germinating in earnest when soil temperatures reach 40⁰F. Once the imbibition phase starts there is no return to dormancy and the germination/emergence should be as quick as possible to establish a healthy, vigorous seedling. Protracted emergence will predispose the seeding to attacks of soilborne fungi like Pythium damping off or common root rot, ultimately reducing stands. Daytime highs in the sixties and night temperatures around 40 are great and will allow the crop to emerge in 8 to 10 days and make for a robust stand.
During this whole germination and seedling emergence and up to the 5-leaf stage, the growing point will be at ~1 inch depth. At this depth it is protected from the ambient temperatures. The crown can sustain temperatures down to 28⁰F and probably even handle short periods of temperatures as low as 22⁰F. Even if above ground leaves freezes, the plant will survive and continue its development as long as the crown does not suffer any freezing injury.

Thus planting this early is a risk if winter returns and temperatures plummet. The immediate forecast, however, looks very favorable for germination and emergence as National Weather Service's extended outlook favors temperatures in the region to average 16-20 ⁰F warmer than normal through the end of March. The 10-day extended outlook looks for daytime highs in the 50 and 60⁰F and nighttime lows in the low 40⁰F or high 30⁰F.

To assess the risk of winter returning in April and the first half of May, I took the weather records from the Northwest Research & Outreach Center that date back all the way to 1890. If we take the latest 30-year climate normal (1981 through 2010), winter can still return in April and when it does, the number of days the minimum temperatures go below 22⁰F between April 1 and May 15 is relatively small at 9% (Table 1). The number of days the nighttime temperatures dips below 28⁰F is much greater at 25%. If however, the warmer weather continues and we look at the 30 warmest Aprils on record, these percentages are cut in half. Taking the warmest 5 April months on record, cuts those percentages again in half. The National Weather Service's outlook for April favors temperatures to average warmer than normal.

Obviously this is somewhat of a roughshod approach as each individual day has its own probability function, meaning that it has its own mean and distribution around that mean. To do these calculations statistically correct you would have to calculate the probability that temperatures dropped below 22, 28 and 32 degrees for each individual day and then average them out over the same time period. Intuitively you would understand that the risk is greatest in early April and diminishes with each day the season progresses.

Bottom line: there is a risk that cold weather returning. Frost is likely to return to the region but the odds of really cold temperatures that could damage the crown appear to be relatively small. Of course, if any snow accompanies the cold weather, the snow will act as insulation and reduce the risk of the crowns freezing.

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Sometimes a picture is worth a thousands words. The photo below of the winter wheat variety trial on the Northwest Research & Outreach Center was taken yesterday afternoon as temperatures were a balmy 39F. The warm temperatures over the past few days have melted the little snow we have had in the surrounding fields. The winter wheat trial was still blanketed, thereby protecting the seedlings.

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By Jennifer Obst, Minnesota Agricultural Experiment Station, 612-625-4741

A comprehensive comparison of most crop varieties grown in Minnesota is now available in print and electronic forms. Minnesota Varietal Trials 2012, published by the Minnesota Agricultural Experiment Station, provides the results of the 2011 University of Minnesota evaluation of more than 1000 individual entries of plant varieties.

By Daniel Kaiser
Extension Soil Fertility Specialist

U of M Nutrient Management Website

A new nutrient management website has been launched that houses most of the current fertilizer suggestions and data from the University of Minnesota. This website was made possible by funding from the Minnesota Agricultural Fertilizer Research and Education Council and was put together through a joint effort for several researchers from the University of Minnesota who's research focuses on nutrient management issues for several crops growth throughout the state of Minnesota.  We would like to thank the AFREC program because without them this effort would not have been possible

Decision Guide for Late Season N in HRSW

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As prices for liquid UAN (28-0-0) have risen sharply the decision guide for late season N in HRSW had became outdated. The updated guide allows for N prices up to $1.00 per pound of actual N. This would equate to roughly $ 3.00 gallon for liquid UAN.

Some things to remember when you contemplating a late season application of N in HSRW are:


  • Apply up to 10 gpa of 28-0-0 with an equal amount of water - the water is needed to reduce leafburn;

  • DO NOT apply during the heat of the day - early evening application reduce leafburn considerably;

  • DO NOT tankmix this N with any fungicides at Feekes 10.51, but rather apply the additional N 2 to 5 days after anthesis;

  • The probability of a response by the crop is about 80%;

  • Only expect an increase of 0.5 to 1.0 full point in grain protein with the additional 30 lbs N/A;

  • All varieties respond equally well to the additional N;

Use the to determine whether an economic return is possibly in relationship to the price of the 28-0-0.
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Aphids in Small Grains and Soybeans: an update from NW MN

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update prepared by Dr. Ian MacRae, UMN Extension Entomologist, NWROC-Crookston

Many field projects are underway and we're scouting small grain and soybean fields to stay on top of what is happening with aphid populations in these crops. Following are comments based on what our field visits are revealing in northwest Minnesota.

Minnesota Small Grain Survey Underway

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A field survey project to inspect wheat and barley fields is underway in Minnesota. The survey program has resumed past efforts where survey scouts visit fields to assess crop progress and pest situations. Inspecting wheat and barley fields for the presence of plant diseases and insects provides a weekly regional snapshot of pest problems present in fields and the status of the infestation levels.

Small Grains Disease Risk Assessment Tools

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Minnesota's small grain disease forecasting model is up and running for the season. You can access the site here. Weather based risk models for tan spot, Septoria leaf blotch, leaf rust, and scab are available on this site. Simple select the disease of interest and a risk map for the state. The models can predict the risk up two days in advance and you can go back up to 365 days prior. You can also drill down to your area of interest with a simply mouse click on your area of interest. Another mouse click on a township's section will give a text summary of the risk for that local for that day and the previous seven days. Scouting reports and other commentary will be updated regularly.

The National Fusarium Head Blight Risk Assessment Tool is also available here. The National Risk Assessment Tool will also provide real time alerts. You can sign up on the US Wheat and Barley Scab Initiative website. Alerts can be delivered as a RSS feed, an e-mail, or as text messages to your mobile device.

The North Dakota Small Grains Disease Forecasting System has also come online for the 2011 season. The NDSU now includes a barley DON forecasting model. The model was developed by Dr. Jeff Stein at SDSU.

Scouts identified tan spot in many spring wheat fields across Minnesota last week. The incidence and severity was generally low. Weekly summaries of this statewide scouting activity that is funded by the Minnesota Wheat Research & promotion Council are forthcoming.

If you are considering controlling early season tan spot, please follow this link to an article that was published in Minnesota Crop News last spring. It describes how and when control of early season tan spot is warranted and lists fungicide choices and rates

If you are considering tank mixing a fungicide with your herbicide program be aware that tank mixing can increase the risk of crop injury with certain combinations of herbicides and fungicides. Research between 2004 and 2006 at the University of Minnesota, showed that combinations of the broadleaf herbicide bromoxynil with several grass herbicides and fungicides can increase the risk of crop injury, especially with cooler weather. The injury is caused by bromoxynil and is temporary with no effect on grain yield. There is, however, a small risk of reduced control of wild oats as the injury that is visible on wheat can also be found on the wild oats. It was postulated that the bromoxynil injury reduced uptake and/or translocation of the grass herbicide, ultimately resulting in a couple percent reduction in control.

By Daniel Kaiser
Extension Soil Fertility Specialist

As the growing season moves forward more questions have occurred about what products to use in side-dress situations. While nitrogen is on the minds of many, sulfur deficiencies are starting to be seen in fields as well. Applying the right product in the right situation at the correct time can be crucial in order to maintain yields and minimize damage to growing plants.

Stand Loss and Replanting Decisions

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Torrential downpours the week prior and again over the Memorial Day weekend caused saturated conditions in many parts of the Red River Valley at possibly the worst time for not only for wrapping up spring field work but also for the just seeded crops. Now that the wheat has emerged, bare areas are quickly becoming evident. A quick survey suggests that in many cases the bare areas are in the ditches and the slightly depressed portions of fields. This points to excess water likely being to main culprit of these stand losses. Excess moisture (anytime the soil water content is above field capacity) depletes the soil of oxygen and germinating seed will quickly die in these anaerobic conditions. A clue whether excess water contributed to a poor emergence in the affected areas is to dig up the remnants of the seed. If the seed is firm and the radicle and coleoptile are white and firm, the emergence was only delayed (Photo 1). If the radicle and the coleoptile are soft and discolored and the seed has turned mushy, the young seedling died in the anaerobic conditions as a result of the saturated conditions.

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Photo 1 - A sprouted wheat seed If you find the coleoptile and or first leave or crinkled up and etiolated right under soil surface, crusting is the main problem. Breaking the crusts as soon as possible will be crucial for the safe as much as possible of the stand and to avoid reseeding. A rotary hoe is the best tool for breaking a crust. A spring-tooth harrow with the teeth set straight down instead of slanted back can sometimes be used. The circular motion of harrow teeth set in this fashion can be very effective at breaking a crust enough for young seedlings to emerge. A heavy rigid harrow should be avoided as too much soil movement may expose seedling roots. If neither of these tools is available, running over the field with and empty double disc drill or a Brillion or Cambridge roller will also break the crust. Replanting decisions will be difficult as the optimum planting window for wheat has basically closed. If reduced stand is uniform (no big skips or holes), keep stands of 15 plants per square foot. After June 1 in northern Minnesota a replant decision should be to a crop other than wheat or barley since yields are reduced by about 50% when planting after these dates compared to normal planting dates.

By: Daniel Kaiser and Jeffrey Coulter
University of Minnesota Extension Specialists

With all of the flooded soils and wet fields there likely are questions on denitrification and whether side-dress nitrogen (N) should be applied. The fact is that it can be difficult to predict the amount of N lost. However, two things should be considered when dealing with denitrification:

Heat Canker and Frost Damage in Small Grains

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The title of this short article may seem a paradox, but leave it to a Minnesota spring to create the conditions for both problems within a day or two. Last night's lows may have caused some frost damage in northwest Minnesota. Fortunately, for spring wheat and barley the damage is cosmetic and will not require replanting. The reason for this is as simple as it is elegant. The tender growing point from which all leaves and eventually the spike is produced is insulated and protected by the soil. Up the approximately the 5-leaf stage the growing point is located at the crown at ± 1.5 inch below the soil surface. The crown is easy to recognize as a hard knob from which both roots as well as leaves start. This evolutionary adaptation to keep the growing point hidden and protected from the elements is precisely why small grains fit so well in this area. Frost damage will initially have a dark green, water soaked appearance that will quickly dry out, leaving the tissue white to tan (Photo 1). Frozen and dried up leaf tips will often break off with a little wind and give the field a very raged appearance. New growth should not show any symptoms.

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Photo 1 Frost injury on young barley plants

The sunny, windy weather and big temperature swings expose the young seedlings to a second abiotic stress. The heat at the soil surface can cause heat canker. The tender young tissue at the soil surface basically will 'cooked' and this appears as a yellow band that is slightly constricted (Photo 2). As the leaf continues to grow, this yellow band (1/8 - 1/4") moves upward and away from the soil surface. If the conditions last for more than a day, repeated bands can become visible. As with freeze injury, the tips of leaves may break off at the yellow band and give a field a very ragged appearance. Damage from heat canker is temporarily and should not affect further growth and development.


Heat-Canker.pngPhoto 2 Heat Canker on just emerged wheat


Emergency Options for Seeding Small Grains

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As the wet and cold weather continues to delay fieldwork and the window for small grain seeding is closing, you may be considering alternatives. Broadcast seeding methods, whether by air or with a pneumatic fertilizer spreader (floater), are an emergency option you can consider if you plan to cstick with small grains. The chances of success are greatly improved when you heed the following:

  1. The broadcasted seed will need to be incorporated with some light tillage. Tillage prior to seeding is less critical if fall tillage resulted in a smooth and even field. A tillage operation following the broadcasting of seed is needed to incorporate the seed. Incorporation is essential to create seed to soil contact needed for successful germination and seedling establishment. Harrowing often is enough. Incorporation of the seed with tillage will result in variable seeding depth.
  2. The seeding rate will need to be increased as the stand loss percentage due to seed placement that is too deep or too shallow will increase. Research in Ohio and Wisconsin with winter wheat showed that the seeding rate needed to be increased with 15%. Local experiences with spring wheat point to an increase between 10 and 20%.

As stated already, broadcast seeding is an emergency option. Using a floater has the advantage that you will be able to spread fertilizer in a single pass. Expect uneven and often delayed emergence. Barley will be most sensitive to incorporating the seed too deep, while oats will have the most tolerance to seed being placed deeper than the optimum 1.5".

Winter Wheat Stand Evaluation

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It's time to determine whether the winter wheat came through the winter well enough to keep the stand. The best way to do this is to do a stand count. To do a stand count, use one of the following two methods:

1) Count the number of plants in a foot of row at several locations in the field. Take an average and convert in plants per acre using Table 1.

2) Take a hula-hoop, let it fall, and count the number of plants inside the hoop. Repeat this at random several times across the field and calculate an average. Use Table 2 to convert the count to an approximate population per square foot or acre.

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Table 1. Average number of plants per foot of row for different row spacing and plant densities per acre.


Table 2 Stand Count Wheat JJW.jpg
Table 2. Adjustment factors to multiply the number of plants inside a hoop and convert the number in to number of plants per acre.

If your winter wheat hasn't started greening up again, you may be wondering if your winter wheat crop survived. To evaluate whether your winter wheat survived, I suggest you do the following: dig up several seedlings across the field and cut them longitudinal (lengthwise) with a very sharp knife or a safety razor blade. If the crowns look white/yellow to light green, they are healthy and will continue to grow. If you find that the crown has turned tan to brown and soft, it did not survive the cold weather.

In addition, you can check whether seedlings will grow by trimming the roots and leaves down to about ¼ to ½ " above and below the crown. Place these seedlings on a wet paper towel and place the towel in a Ziploc bag or plastic container that can be sealed. Place the container at room temperature and check for re-growth in 24-48 hours. Viable seedlings will show re-growth almost immediately (Photo 1). It will take longer than usual, but as long as the crown is healthy, a stand will establish and your field of winter wheat may not need to be destroyed.


Photo 1 Stand Count Wheat JJW (2).png
Photo 1 Regrowth of young winter wheat seedlings after 36 hours incubation in a Ziploc bag at room temperature (photo courtesy of Blake Vandervorst)


If stands across the fields average 15-17 plants/ ft2 or more you can leave the stand and expect near maximum grain yields. Often winterkill is not evenly distributed across a field but rather patchy. Smaller patches with stands as low as 8 plant / ft2 are probably worth saving. Weed control will be more troublesome with thin stands and the crop's growth will be variable making management decisions such as the correct timing of a fungicide application more difficult. If the patches with complete winter kill are larger than a couple if square feet and cover more than 20% of an area, such as in a ditch or on a knoll you may still want to consider replanting that area of the field to something else.

Late Planting of Small Grains

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As the month of April draws to a close, little if any field work has been started across Minnesota. As of this past Monday, the National Agricultural Statistics Service reported that only four percent of the oat and no spring wheat had been planted. With the immediate forecast not looking particular encouraging, it appears that most of the small grains acreage will be seeded past the optimum planting window.

The link below points to a Minnesota Crop News article that summarizes the effects of planting wheat, barley and oats past the optimum planting window:

Late Planting of Small Grains

Recommended Malting Barley Varieties for 2011

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The American Malting Barley Association, Inc. (AMBA) recently announced the recommended malting barley varieties for the 2011 growing season. Two new six-row varieties and one two-row variety have been added to the list. Quest, the latest release from the University of Minnesota barley breeding program is the first recommended variety developed from Fusarium Head Blight resistant germplasm from Switzerland and China. Quest averages 40% lower in DON than current varieties. The other six-row variety added to the list is Celebration, developed by Busch Agricultural Resources. The other addition to the recommended list is Pinnacle, a two-row malting variety released by North Dakota State University.

Other recommended varieties suited for Minnesota include the two rowed variety Conlon and the six-rowed varieties Lacey, Legacy, Rasmusson, Robust, Stellar-ND, and Tradition. Drummond has been dropped from the list.

Malting barley growers are encouraged to contact their local elevator, grain handler or processor to gauge market demand for varieties grown in their region prior to seeding.


Authors: Dimitre Mollov and Jennifer Flynn

When crops or plants are not growing well and look diseased or less vigorous than healthy plants, an accurate diagnosis of the problem may be critical to reducing and managing it. The Plant Disease Clinic at the University of Minnesota in St. Paul is open year-round to diagnose crop and plant problems and to assist with other plant testing questions. The Plant Disease Clinic welcomes samples from anyone and offers a wide variety of diagnostic and testing services.



Feekes 10.51: A Pictorial

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The recommended timing for fungicide applications to suppress Fusarium head blight or scab is Feekes 10.5 in barley and Feekes 10.51 in wheat. At growth stage Feekes 10.5 the inflorescence or spike is completely emerged from the boot. Photo 1 shows the progress of the heading procres in barley. The third kulm is at Feekes 10.5 and the correct growth stage to receive a fungicide to suppress FHB. Photo 2 shows the progressing of the pollen shed in durum wheat; in the first kulm no anthers are visible on the outside of the individual florets, while in the second kulm the anthers are only visible in the center section of the spike. As these anthers are still yellow, they likely shed pollen earlier that day. In the third pollen shed is complete as anthers are visible across the length of the spike and are bleached and desiccated. The second photo closely approximates Feekes 10.51. The progression in spring and winter wheat is identical to the progression in durum wheat.

Note that not all varieties will extrude the anthers in which case anthers may not become visible on the outside despite the fact that pollen shed is complete. It is always a good idea to peel back the glumes in the center of the kulm and inspect the color or the anthers as you scout fields. If the anthers are yellow, pollen shed will likely commence that day.

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Photo 1: The progression of the heading in six-row spring barley (photo courtesy of Joel Ransom, NDSU).

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Photo 2: The progression of anthesis (pollenshed) in durum wheat (photo courtesy of Joel Ransom, NDSU).

Purple Auricles in Wheat

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The auricles in wheat are defined as the clasping appendages or the claw-like projections that are located at the junction of a leaf sheath and the leaf blade. Auricles in combination with the shape of the ligules are two anatomical features used to distinguish grassy species from another, such has in this identification key.

The auricles on most of our wheat and barley varieties are pale green. A few recent releases have purple auricles. Below is a close-up picture of the auricles on the cv. 'Faller'. This coloring is the result of the presence of anthocyanins and is a heritable trait. Expression of the trait is, however, not stable and you may find different levels of coloring from year to year. There is no reason to be concerned about this coloring.

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Photo 1: Purple auricles on the cv 'Faller'.

Late Season N in Wheat - The Cliff Notes Edition

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Based on the number of phone calls I received in just the last few days there is a considerable amount of interest in late season application of nitrogen with the goal to improve the grain protein content of spring and winter wheat. This interest isn't surprising given the extremely low grain protein concentrations of last year's crop and the crippling discounts that followed. Foliar applications of N during the onset of kernel fill have shown to be able to increase grain protein. A review article and decision guide were published in 2006 and can be found here.

The key points of foliar applications of N on wheat to improve gran protein content are:

  • Apply up to 10 gpa of 28-0-0 with an equal amount of water - the water is needed to reduce leafburn; more water is advantageous
  • DO NOT apply during the heat of the day - early evening application reduce leafburn considerably
  • DO NOT tankmix this N with any fungicides at Feekes 10.51, but rather apply the additional N 5 to 7 days after anthesis
  • The probability of a response by the crop is about 80%
  • Only expect an increase of 0.5 to 1.0 full point in grain protein with the additional 30 lbs N/A
  • All varieties respond equally well to the additional N
  • Use the decision guide in the above mentioned link to determine whether an economic return is possibly in relationship to the price of the 28-0-0


Risk of Fusarium Head Blight in Wheat on the Rise

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Wheat crops in the flowering stage are now at risk for FHB infection across most of the state, with highest risk in the NW region of MN. Winter wheat either already flowered or is flowering now, while some of the first planted spring wheat is close to flowering.

Risk is highest for susceptible to very susceptible cultivars. The 24-72 hour forecast indicates that the risk will remain or even get higher in the next few days.

When considering the application of a fungicide to suppress FHB, assume that all winter wheat varieties are susceptible to very susceptible to FHB (http://www.ag.ndsu.edu/pubs/plantsci/smgrains/a1196_08.pdf). The spring wheat varieties rate from moderately resistant to very susceptible. The ratings can be found in the Minnesota Variety Trials Bulletin (http://www.maes.umn.edu/10varietaltrials/redspringwheat.pdf)

Disease pressure of other diseases is high for tan spot but low for leaf rust as it appears that little leaf rust inoculum has made it this far north to date. Powdery mildew can readily be found in Lake of the Woods and Roseau counties and central Minnesota.

Fungicides labeled for an application at Feekes 10.51 include Folicur, several generic versions of Folicur, Caramba, and Prosaro. Extensive university studies comparing Prosaro and Caramba fungicides with Folicur show that Prosaro and Caramba provide a 20% better reduction of FHB and a 30% better reduction of vomitoxin than Folicur, when tested on moderately susceptible to susceptible cultivars.

The risk maps of the different diseases, including FHB, for Minnesota can be found at the Minnesota Association of Wheat Grower's Fusarium Heab Blight Forecasting website (http://mawg.cropdisease.com). The website also creates risk maps for tan spot, Septoria leaf blotch, and leaf rust. Access to the national risk map may be found at www.wheatscab.psu.edu/. The NDSU disease forecasting site can be found at www.ag.ndsu.nodak.edu/cropdisease.

Sign-up for Fusarium Head Blight Alerts

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Producers and ag professionals that are interested in the potential risk for Fusarium head blight in wheat and barley can sign-up for a national alert system. These alerts are delivered either short text messages (SMS) on mobile phones or as e-mail messages.

Go to the National Scab Initiative website (http://scabusa.org/fhb_alert.php) and chose which way you would like the alerts to reach you and from which state or states and regions you would like to receive the alerts.

These alerts are made possible through the collaborative effort of teh US Wheat and Barley Scab Initiative and the national FHB Prediction Center at the Pennsylvania State University.

The alerts for Minnesota will be provided in collaboration with Marcia McMullen, NDSU's extension plant pathologist, and others in the region.

Yellow Wheat

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History repeats itself ever so often and unfortunately excess precipitation in many part of the Red River Valley has caused once again overland flooding and saturated field conditions. Wheat and barley can handle some flooding but it is not without a cost. As the water recedes and the soils drain you will likely notice that the wheat crop (and barley for that matter) has turned pale green or even yellow. In 2008 Doug Holen, Dan Kaiser and I wrote a short a summary of the causes of this yellowing and the possible solutions. Below is a nearly complete reprint is that article:

Some of the common reasons for early season yellowing are:

- Temporary nitrogen deficiency
- Temporary herbicide injury
- Early tan spot infection

Other possible causes include Barley Yellow Dwarf virus or temporary micro nutrient deficiencies.

The nitrogen deficiencies can readily be indentified as the symptoms are worst on the oldest leaves and start at the tip of the leaves, progressing towards the base as the deficiency gets worse. The causes of the N deficiencies are several, all which have common denominator, namely excess precipitation. Excessive rainfall causes:

- Leaching
- Denitrification
- Inability of the plants to take up available N

Leaching is a potential problem in coarser textured soils. Saturated soils/standing water will cause both denitrification and inability to take up available N. Denitrification is a microbial process and speeds up considerably as soil temperature increase. According to Univ. of Illinois data (Hoeft, 2004), denitrification losses are 1-2% if soil temperatures are less than 55°F, 2-3% when soil temperatures are between 55 and 65°F, and 4 -5% once soil temperatures exceed 65°F. As soils are saturated, the plant's roots also are unable to take up N - even if available. Often the crop recovers quickly if the growing conditions improve and the excess water has drained.

If the N deficiency is severe, a supplemental application of N as either urea (46-0-0) or urea ammonium nitrate solution (28-0-0) can be advantageous. Research by Russ Severson in 2002 showed that 40 lbs of supplemental N at the 4 leaf stage yielded 7 bu/A extra over the untreated check. As excess rain saturated soils and yellowed the wheat crop that spring, he designed a small, replicated trial in which he looked at the impact of timing of supplemental nitrogen. The wheat followed corn. Prior to the supplemental N, the field had received 80 lb. N per acre as 82-0-0 and 50 lb. 18-46-0 per acre. The supplemental N was applied at either Zadoks growth stage 14 or Zadoks growth stage 60.

The early application of fertilizer N increased yield by 7 bu/A when compared to the wheat that did not receive supplemental N. The later application did not increase grain yield compared to the untreated check. Even at today's N prices that would be an economic return.

The cool and wet conditions have made some of the micro nutrients also less available to the plant. These symptoms are often first noted on the coarser textured soils. George Rehm has chased this problem in the past and found that no single culprit was to blame. As soon as growing conditions improved, the symptomology would disappear.

The cool growing conditions have also made a number of our common small grain herbicides more prone to cause temporary injury. Especially the ACCase class of grass herbicides is more active with cool(er) growing conditions. This temporary yellowing will dissipate in one to two weeks after application with no effect on grain yield.

Early season tan spot infection can also cause the young wheat crop to turn a bright yellow. Especially young seedlings up to the 3 to 4 leaf are very sensitive to a toxin that is produced by the fungus. This yellowing affects the whole seedling. If tan spot is identified as the cause of the yellowing, an early season fungicide treatment is warranted. Half a labeled rate of any of our labeled fungicides - e.g. Tilt, Quilt, Stratego, and Headline - can be used to halt the development of the tan spot and allow the crop to recover.

EARLY SEASON TAN SPOT

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Early season tan spot can be readily found across the Red River Valley. Especially in wheat on wheat situations the disease can readily be found. One of the characteristic symptoms of these infections at the 2 to 3 leaf stage is a yellowing discoloring of whole leaves. This is a more extreme expression of the same the yellow halo that surrounds the tan spot lesions in more mature plants. Be careful not to mistake this yellowing for a nitrogen deficiency.

There are a number of fungicides registered for control of early season leaf spot diseases in wheat. The table below lists the products that are available and the recommended use rates.
10 Fungicide Table Early Season Wheat.jpg

Research at both NDSU and the University of Minnesota has shown that once early season tan spot is left uncontrolled, yield reductions of 4 to 5 bushels will result if conditions continue to favor the development The greatest economic response from early season fungicide use occurs when susceptible cultivar are planted into wheat stubble. Even fields that were in wheat two years ago may have enough remaining wheat residue at the surface to see low levels of tan spot infection.

Most of the fungicides can successfully be tank mixed with the commonplace herbicides. Always check the label of both the herbicides and fungicides for tank mix restrictions. Research at the Northwest Research and Outreach Center has shown that the combination of any of the EC formulations of fungicides in combination with the common wild oat herbicides (Puma, Discover, Axial, Silverado) and Bronate Advanced can result in some bromoxynil injury on the both wheat and wild oats. This injury generally didn't affect grain yield of the wheat or the control of the wild oat, except in the combinations that included Silverado in which case wild oat control was diminished.

High Temperatures, Spikelet Counts, and Yield Potential

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Much of the earliest planted wheat in the Red River Valley is approaching the 5 leaf stage. At this time the initiation of the head has begun. After the number of tillers that were initiated over the past three weeks, the number of spikelets is the second the three yield components that ultimately will determine yield. Like tillering, the number of spikelets is also greatly influenced by temperature. The figure below show what happens as the average maximum temperature increases from 65 to 85; the average spikelet counts declines almost by a third from 17 to 13.
10 Spikelet Count.jpg

Although cooler daytime temperatures would be desirable to maximize the yield potential, you shouldn't be completely discouraged or disillusioned. The beauty of wheat is its great ability to compensate between yield components. If the conditions during anthesis and grain fill are favorable for wheat the crop will put its energy in additional kernels per spikelet (3 to 4 rather than 2 to 3) and larger kernels.

I have received reports and observed it myself - there is a lot of volunteer spring wheat that has survived the winter and is happily growing right this moment in some fields in the region (Photos1 and 2). Interestingly, it appears to be limited to certain varieties. The HRSW variety 'Faller' has been positively identified as a variety that is showing this survival. I'm interested to hear whether you have fields in which volunteer spring wheat survived the winter and which varieties, other than Faller, are in those fields. Simply e-mail (wiers002@umn.edu) me or call me (218-281-8629).

Photo 1 small.jpg
Photo 1 - Stand of volunteer spring wheat that survived the 09/10 winter near Crookston.
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Photo 2 - A few volunteer spring wheat plants that survived the 09/10 winter near Crookston.

By Daniel Kaiser and Jochum Wiersma

Decisions about the amount of nitrogen to apply in wheat and barley are challenging each and every year as the return per acre is not simple a function of the price of the commodity but also on the quality (grain protein %) of those bushels. There are opportunities to capture premiums for protein but more often than not producers are faced with discounts as the grain protein percentages fall below the market's 14% threshold.  While this was already an issue in 2008 with high yields in Northwest Minnesota leading to lower protein, it was greatly magnified in 2009 with producers reporting grain protein percentages of 10% or less.  This issue is not new since it has been long noticed that yield and protein are inversely related. The amount of grain protein produced per acre appears to be relatively constant over years. In high yielding years the extra starch produced  simply dilutes the total protein produced per acre leading to smaller percentages in the grain  Unfortunately farmers are not paid for total production of grain protein per acre but rather they are paid for concentration in grain.

HRSW Varieties with a Higher Risk of Preharvest Sprouting

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The continued wet weather and harvest delays are increasing the potential for preharvest sprouting. Once the dormancy of the seed is broken and sprouting is initiated the quality of the grain deteriorates, grain elevators will check for this decline in quality using the Hagberg Falling Numbers test. The HRSW that are ranked moderately susceptible to pre-harvest sprouting are listed in Table 1. Understand that the potential for preharvest sprouting increases if you swath the grain or if you leave it stand too long while waiting for the grain to reach 13% moisture, all the while rain and heavy dews are forecasted. Rather, harvest the grain as quickly as possible and as soon as moisture content approaches 15% as HRSW can be readily stored up to three months at that moisture content.

Table 1 - HRSW varieties with a higher risk of preharvest sprouting

Variety Preharvest Sprouting Rating*

Bigg Red 4
Blade 5
Granger 4
Hat Trick 4
Sabin 4
Samson 4
Traverse 4

* 1=best, 9=worst

Final Words of Caution on Wheat Midge

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by Phillip Glogoza, Extension Educator - Crops


A lot of wheat is now heading in NW Minnesota. In the northern most counties, degree day accumulations are just reaching the 1300 DD mark (see map), the point where 10% of female midge have emerged. Emergence will continue through 1600+ DD (90% female emergence).

by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist


Crop growth stages of spring wheat are rapidly approaching early flower in some locations. This is the time of year that managers must make a decision to apply a fungicide application targeted for Fusarium head blight (FHB) management.

Watch for Midge as Wheat Approaches Heading Stage

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by Phillip Glogoza, Extension Educator - Crops

There could be about 70% of the region's wheat acres at the heading stage when wheat midge are emerging, based on those acres being planted in the high risk window (Figure 1). Heading is the growth stage when wheat is attractive to female midge for egg laying, and the time the plant is most susceptible to injury from midge larval feeding. Though midge populations have been small in recent years, this will be the most wheat acres we have had that are susceptible to midge in many years.

Aphids in Small Grains - June 29, 2009

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by Dr. Ian MacRae, U of MN Extension Entomologist

There have been some reports of bird cherry-oat aphids (Figure 1 and Figure 2) in small grains in NW and WC MN over the last week. The populations I've seen are at very low numbers. Add to this, the recent rainy weekend will likely have had a significant impact on those aphid populations, but it's still a good idea to scout for aphids in small grains. The most damaging aphid populations are ones that reach threshold around flag leaf stage, if populations are at or near threshold at this time, delaying treatment until heading may cost you yield.

Bacterial leaf stripe of wheat: Something to keep in mind

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by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist

Bacterial leaf stripe is a disease that can usually be found on wheat in the Red River Valley (RRV) later as crop growth stages progress. The disease (caused by a Xanthomonas sp.) can develop and become severe rapidly after the crop reaches the heading growth stage. Bacterial leaf stripe (BLS) can cause significant yield losses on some varieties. Like other disease issues, development is dependent on weather conditions and the presence of susceptible plant hosts. Epidemics of BLS occurred in the RRV during 2005 and again in 2008.

Losses in Wheat due to Flooding and Waterlogging

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Northwest Minnesota continues to be plagued by excess precipitation. Consequently many field or lower lying portions of fields are repeatedly flooding or are - at a minimum - completely waterlogged. Flooding and water logging causes a rapid depletion of oxygen in the root zone. In turn, this oxygen deficiency affects several physiological processes such as the uptake of water, the uptake and transport of nutrients, and the root/shoot hormone relations.

Wheat can probably handle 3 to 4 days of flooding and/or water logged soils before grain yield is impacted negatively as long as some of the leaves are above water. Higher temperatures will hasten the depletion of oxygen and increase the risk of damage to the crop. Acute nitrogen deficiencies are most commonly observed with the crop yellowing quickly. The waterlogged soils not only impair nitrogen uptake, denitrification and leaching further exuberate the problem. Extended periods of water logging reduce leaf elongation, kernel number, and ultimately grain yield.

Yield losses than have been reported in the literature range between 20 to 50% when soils were water logged in excess of 10 days. One study in winter wheat reported a yield loss of about 2% for each day soils were waterlogged. Several study, however, have also noted differences in water-logging tolerance among wheat varieties.

One of the characteristics that were observed of varieties that handled water logging better than other varieties was the ability of varieties to initiate adventitious roots of the first node (Photo 1). I have observed this trait in some of our spring wheat varieties but neither I nor any of the breeding program in the region have dedicated screening or evaluation nursery for this trait.

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Photo 1. Adventitious roots on the first node of a wheat stem visible after three days of flooding near Crookston in 2002.

Wireworms in Small Grains

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by Dr. Ian MacRae, Extension Entomologist

I've received reports of wireworms in small grains this season - not surprising this year given that wireworm tend to be more active in cooler conditions. There are several species of wireworms in the Red River Valley and although they're usually neither a frequent nor wide-spread problem in the RRV, when they do occur, damage can be quite significant even leading to a total field loss.

Causes of Seedling Stand Losses in Spring Wheat

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Seedling stand loss is defined as the percentage of viable seed that fails to become a healthy plant. In order to understand the causes of stand loss we need to also define seedling vigor. Seedling vigor is defined as those seed properties that determine the potential for rapid, uniform emergence and development of normal seedlings under a wide range of conditions. Causes of seedling stand losses can be categorized in three broad categories - intrinsic attributes, biotic stresses, and abiotic stresses.

Both seed size and grain protein content have been shown to improve seedling vigor in spring and winter wheat seed lots of the same cultivars that have higher seed weight and/or grain protein content will have more seedling vigor. Some of the research, however, suggested that there was no need to remove the smaller seed fraction from a seedlot as long as the seedlot had commercially cleaned as there often wasn't a yield difference at the end of the season despite differences in seedling vigor. Some of the same research, however, did shown that were significant differences in seedling vigor among spring wheat cultivars and the authors of the studies suggested that breeders use it as a selection criterion in their breeding programs.

A cold stress test in addition to the standard germination test is a method to test seedling vigor of a breeding line, variety or seedlot. Corn breeders routinely use this test as a selection criterion in their breeding programs. I am not aware of any spring wheat breeding programs that use the cold stress tests in their breeding program. This can probably be explained by the fact that corn is more often seeded in - for corn - cold soils resulting in protracted germination and seedling emergence.

The physiological age of the seed is also an important parameter that influences seedling vigor. A standard germination test is used to determine the percentage viable seed under ideal conditions. There is also the 'accelerated aging test' to discern seedlots with poor seed vigor and excellent seed vigor. This test is routinely conducted in soybeans and corn but again seldom used in wheat. This too can probably be explained by the fact that corn and soybeans are more often seeded for their species in cool soils, resulting in protracted germination and seeding emergence.

Biotic stresses that cause stand losses include whole host of fugal diseases. Saturated and/or cold soils can aggravate the incidence and severity of a number of fungal seeding diseases including Pythium damping off.

Abiotic stresses that cause stand losses are water, temperature, and/or distance to the soil surface. Excess moisture (anytime the soil water content is above field capacity) depletes the soil of oxygen and germinating seed will quickly die in these anaerobic conditions. High temperatures in excess of 90F can induce a dormancy that will prevent germination. This dormancy is not broken until temperatures drop below 50F. Seeding too deep will prevent to coleoptile to reach the surface, and consequently, the first leaf will not get above ground. The seedling will ultimately die although an etiolated and crinkled up first leaf can often be found just below the soil surface. Crusting of the soil can give a similar result. Seeding too shallow or in a seedbed that is very cloddy poses the risk of poor seed to soil contact. In either case, the seed can not in imbibe enough water for germination to start. This seed will stay viable until a rain improves seed to soil contact and adds water into the upper soil layer. A big risk, however, is that the seed will start to imbibe water but that wind and/or warmth desiccate the seed again. This almost always means the death of the germ.

Judging from some of the fields I have surveyed, the shallow seeding and the anaerobic conditions have contributed equally to the uneven emergence we see in many fields. A clue whether shallow seeding contributed to a delay in emergence is to dig up the seedling and measure the distance from the crown to the tip of the coleoptile. You also count the number of leaves of these seedlings and compare this to the better parts of the field. Given the fact that it takes about 180 GDD for each leaf to appear, you can use the difference in development to reconstruct whether the seed lay in dry dirt; the number of days needed to accumulate difference in GDD should be equal to the number of days between seeding and the first rain received after seeding.

Now is The Time to Evaluate Stands

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The challenging spring in Northwest Minnesota has forced many to seed their wheat and barley under less than ideal conditions and into poor seedbeds. Now is the time to evaluate how well your seeding operation went and what the attained stands are. This is important as the decision about inputs further into the season will depend on the yield potential that is left.

Orange Wheat Blossom Midge: Vigilance is in order

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Orange wheat blossom midge (Figure 1) as a wheat pest has been off the front page as a major production problem in NW MN for many years. Populations in the region have been small enough that significant outbreaks and associated yield losses have been of small concern. However, we learned in the mid-90’s that given the right circumstances, this insect can increase its population rapidly and cause major yield losses in a very short time frame.

Blending of Wheat Varieties - II

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In a previous article that appeared in Prairie Grains Magazine and the Farm & Ranch Guide blog, I discussed the merits of blending different varieties of spring wheat. The harsh winter and spring have added another dimension to this discussion that demands some attention.

Seeding Rates in Hard Red Spring Wheat

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Jochum Wiersma, Small Grains Specialist, University of Minnesota Extension

Each year questions arise about the correct seeding rate for hard red spring wheat. ‘Is a bushel and a peck enough?’ is a question I have been asked more than once.  Research in the mid nineties demonstrated that - on average - an initial stand of 30-32 plants/ft2 maximized grain yield. As planting was delayed past the optimum, the initial stand needed to be increased by ~ 1 plant/ft2 for each week of delay to maximize grain yield. With this number in mind and assuming a stand loss between 10-15% one can calculate a seeding rate using the following formula.

Late planting of small grains

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Jochum Wiersma
Small Grains Specialist, University of Minnesota

Wheat, barley, and oat are cool season annuals and are most productive when they grow and develop during cool weather. The yield potential of a crop is largely determined by the 6 leaf stage. Cool temperatures during this period are particularly important for the development of a high yield potential. For example, the number of
tillers that ultimately produce grain at harvest declines as planting is delayed (Figure 1). The number of spikelets per spike is determined during the 4 to 5.5 leaf stage (Figure 2). Spikelet numbers are negatively correlated with temperature; spikelet numbers are greater when temperatures during the 4-5.5 leaf stages are cool.

Phillip Glogoza and David Nicolai
Regional Extension Educators-Crops, Moorhead and Hutchinson, MN

Grain harvest is in full swing across the state. It is not too late to review basic on-farm grain storage principles for maintaining quality of stored commodities. Harvest should include preparation of storage structures to receive grain. Preparation includes several practices that aide in preventing pest infestations from developing within our storage structures.

Multiple practices should be implemented on farm to maximize grain quality. These include using appropriate production and harvest practices, maintenance and proper use of grain handling equipment, drying systems and storage structures. There are four simple steps to maintain post-harvest quality sanitation, loading, aeration, and monitoring to protect stored grains from insects, weather, rodents, self-heating, molds, mycotoxins, and pesticide residues.

Jochum Wiersma, Small Grains Specialist

Under certain conditions, the appearance of necrotic areas on flag leaves in wheat can look like a severe disease outbreak. Symptoms can be described as a dying back of the flag leaf from the tip of the leaf downwards (Photo 1 and 2).

Growth and development guide for spring barley

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P.M. Anderson, E.A. Oelke, and S.R. Simmons

Barley ( Hordeum vulgare L. ) originated in the Eastern Mediterranean region. Barley can be distinguished by differences in head type and growth habits. In a six-rowed barley, three kernels are formed at each node of the head while in a two-rowed type, only a single kernel forms at each node ( figure 1 ).

Barley is also classed by its requirement for cold temperatures. Winter barley must be planted so that seedlings will be exposed to cold (vernalized), which enables it to later produce heads and grain normally. Winter barley is usually sown in the fall for exposure to low temperatures during the winter and then development is completed during the following spring and summer. Spring barley does not require exposure to winter temperatures and can be sown in spring. Winter types usually mature somewhat earlier than spring types. Growth and development of the six-rowed spring barley commonly grown in Minnesota will be considered here. Figure 2 shows major developmental stages in spring barley with the approximate time and heat units required to reach each stage. Differences in maturity exist among varieties.

Barley production has become more intense and complex in recent years. Crop managers must understand barley development and be able to recognize growth stages because of the increased use of growth stage sensitive production inputs such as chemical fertilizers, pesticides, and growth regulators.

Growth and development guide for spring wheat

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S.R. Simmons, E.A. Oelke, P.M. Anderson

Wheat ( Triticum aestivum L. ) can be classified as winter or spring growth habit based on flowering responses to cold temperatures. Winter wheat development is promoted by exposure of the seedlings to temperatures in the 38 degrees to 46 degrees F (3 degrees to 8 degrees C) range. Such types are usually planted in the fall which exposes the seedlings to cold temperatures during late fall and winter. Spring-types, however, do not require exposure to cold temperatures for normal development and can be planted in spring. Both winter- and spring-types, when properly grown in Minnesota, head in the late spring or early summer and mature by mid- to late-summer.

The description of wheat development provided here applies mostly to spring wheat, although the basic development patterns for all cereals are similar. Figure 1 shows major developmental stages in spring wheat and approximate time intervals between them in Minnesota. A difference in maturity may exist among varieties or between seasons.

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