Minnesota Crop News

Iron Deficiency Chlorosis Research in NW Minnesota

2013-05-09T14:32:04Z

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.

]]> John Wiersma outlining research findings conducted over many years in the Red River Valley. Click on the link to the PDF file to read more.

Fe Chelates_Wiersma.pdf

Does My Soybean Crop Need Sulfur?

2013-04-26T15:38:35Z

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.]]>
We have been mainly focused on researching sulfur response for corn. One thing that seems to come to the forefront in this research is the overall importance of soil organic matter when considering where a yield increase will occur. For soybean it is not that simple. If you go through much of the research from around the country there is not much supporting evidence for recommendations for sulfur application to soybean. I believe much of any potential for response of soybean to sulfur is related to a few factors, the most important of which revolved around climatic conditions. Where we saw the response was in 2009 which was a year that saw very large responses to sulfur in many of our corn studies. With temperatures being cool and with most areas being relatively dry the potential for mineralization of sulfur from organic matter was low. Two other factors I think were important at the locations were the soil and the previous history of sulfur deficiency symptoms in other crops (alfalfa and corn). The site was on a silt loam soil in southeastern Minnesota with an organic matter concentration that averaged less than 2.0% in the top six inches. All these factors together created a perfect storm in terms of creating conditions were a sulfur application would benefit soybean.

Other than the field location in 2009, there was one other instance that I know of where sulfur benefitted soybean at the Southwest Research and Outreach Center at Lamberton. In this instance soybean yielded higher with sulfur, but the sulfur was applied before the previous corn crop. To follow up on this response we set up trials to look further into the sulfur cycling within corn-soybean rotations to better understand if there are greater benefits from application before the corn crop. One thing that we found in the studies in 2008 and 2009 is that we increased the amount of soybean plant material relative to the total grain produced, meaning we had more plant material per acre. When sulfur and phosphorus were added with N there was a large increase in soybean vegetative growth at all locations. This concerns me due to extra water usage in dry years and potential for disease pressure to increase.

So what are the overall benefits? Increased yield is the overall goal but I do not think that there is a widespread need for sulfur to be applied on all soybean acres. I think the best bet would be to look at fields that are in a areas prone to sulfur deficiency on corn or alfalfa, soil organic matter is around 2.0% or less, and the field has not had any sulfur (including manure) applied to it for several years. In this case 10-15 lbs of sulfur broadcast per acre should be enough for soybean. I would suggest not applying high rates of nitrogen and phosphorus with sulfur. In our field trials we broadcast potassium sulfate and did not see the large increases in plant mass. Another source that may work is gypsum.

I do not think sulfur needs to be applied to soybean if it was applied the previous year. Based on all of the data we have there does appear to be enough sulfur cycling from year to year that the soybeans crop should have enough. Sulfur does leach out of the soil but the relative rate it will leach is lower than some other anions. In coarse sand our data indicates that given enough rainfall any sulfate applied will be below the 2 foot depth in the soil by the middle of the growing season. Even with a small increase in clay content that rate can be reduced. At another site with a loam soil texture we just started to see elevated levels of sulfate by the end of the growing season. Thus, there will likely be some sulfate still in the profile for the soybean crop as long as rainfall is not too excessive.

The other aspect we have been studying is sulfur cycling in corn residue. Based on the information I had a few months ago there did not appear to be much, if any, sulfur that would mineralize from the breakdown of corn stover. However, a more recent set of data shows that it may be possible. From the data we have now, without sulfur, the ratio of carbon to sulfur tends to maintain at a point where the breakdown of corn stalks will not release or tie up sulfur. However, when we looked at the data from 10 and 20 lbs of sulfur applied to corn, the ratio became smaller indicating a potential for a small amount of sulfur to be potentially released. The amount released will again depend on soil temperature, moisture, and tillage to incorporate the residue. This cycling mechanism may explain some of the response we saw in 2009. We also studied higher rates, but the effect appeared to not extend past 20 lbs of sulfur.

To reiterate, if sulfur is applied before another crop I do not think it needs to be applied before soybean, especially corn where the chance of a profitable return is much greater. I think yield can still be increased without a direct application and we also have evidence to increases in grain protein concentration when sulfur was applied before corn. These increases have only been identified in our work in Southeastern Minnesota at this time. While most of our evidence does not support widespread use of sulfur on soybean, some of the isolated responses indicated that some changes needed to be made to our recommendations. Moving forward we will continue to study the cycling mechanisms in order to provide the most up to date information for our current guidelines.

Fertilizing Soybean in Minnesota

Planting Window for Small Grains Already Closing

2013-04-19T14:47:27Z

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.

Spring Nitrogen Managment Options for Small Grains

2013-04-02T00:36:35Z

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.
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The fertilizer guidelines for wheat and barley were recently updated for the state of Minnesota. Included in these guidelines were maximum fertilizer rates suggested for small grains. This data originated information summarized from a publication out of NDSU.

Fertilizer Application with Small Grain Seed at Planting.

While publications like these may give a general idea of application rate they may not be fool proof and should not replace sound judgment. When applying N with the air seeder or drill that all N should be accounted for. This includes N in MAP, DAP, AMS, or Microessentials. It is also important to remember that most suggested rates are based on situations where soil moisture is adequate. It may be necessary to reduce rates by at least half or more if soils are dry at planting. In addition, if potash (KCl) is included the risk for damage may be greater. Remember that all fertilizers contain salts, but vary in their risk for seed placement. Keeping this in mind there are some options out there to but always be up to date on current information to make an informed decision.

Fertilizing Wheat in Minnesota
http://www1.extension.umn.edu/agriculture/nutrient-management/nutrient-lime-guidelines/docs/FO-3772-C-1.pdf

Fertilizing Barley ini Minnesota
http://www1.extension.umn.edu/agriculture/nutrient-management/nutrient-lime-guidelines/docs/AG-FO-3773-B-1.pdf

Soil Testing For K

2013-04-01T15:37:50Z

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.
]]> included from soil samples collected at a plot near Red Wing in the fall of 2012. This typifies some of our locations in the past two years where the field moist test has actually returned higher values than the air dry tests. With the dry soil conditions complicating matters, we really do not know whether one is actually correct in assessing the potential for a deficiency of K in out soils. The fact is that we are too early in our work to tell the difference between the two tests. If fact, our current calibration data shows that there is no difference in the assessment of crop response between a sample run field moist and air dry, even with the handful of locations testing higher with the field moist analysis. We currently are trying to expand research into poorly drained fields as these should represent conditions where the field moist potassium test has a better chance of coming back lower than the air dry test. The fact of the matter is that we know there are likely issues out there but have no concrete evidence to show where they are occurring.

Even with some of the issues noted I would like to make it clear that I have full confidence in the current analysis methods being used for testing K by soil testing labs in the state of Minnesota. Again, we are looking at these issues closely but the development of the field moist test and if we do find some evidence that it better predicts K response in some soils it will become publically available. The moist test is a different test than the air dried samples, and the value of the field moist cannot be directly converted to an air dry test. Because of this all new field calibrations will have to be established prior to any recommended use of the field moist test for potassium. This is very important for anyone thinking of having sample run at a lab using field moist testing for potassium. A few labs are currently running samples on a field moist basis, but until it is clearly demonstrated that the field moist test better predicts potassium response it will not be recommended for use in the state of Minnesota.

We currently are in the process of establishing a soil test sentinel program to study changes in soil test over time across the state of Minnesota. More information will be available in another e-news release on this program. One of the factors we intend to study is the difference between field most and air dried samples for testing for potassium and how they change at a fixed point in space, over time. What this program entails is taking soil samples from a fixed area of any field every 4 to 6 weeks and sending the sample to Daniel Kaiser at the Saint Paul campus. What we are attempting to research is how soils from around the state vary in the difference between the two tests to get a better understanding if and where problem soils may be found. With the diversity of soils this it is important to know how soils may differ. Support for this program is coming through check-off dollars supported by AFREC. Additional information will be available and can be obtained by contacting Daniel Kaiser at dekaiser@umn.edu.

U of MN Field Crop Trials Bulletin Available

2012-12-21T21:33:38Z

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.

]]> Plant varieties tested include alfalfa, barley, birdsfoot trefoil, canola, corn for grain, corn for silage, oat, soybeans, spring wheat, and winter wheat. Trials were conducted at Research and Outreach Centers across the state at St. Paul, Becker, Crookston, Grand Rapids, Lamberton, Morris, Rosemount and Waseca, and also in farmer's fields. Results are from replicated trials conducted at several locations, which allows growers to evaluate how varieties performed across various environments, while accounting for variability within a location and across locations.

The variety trials bulletin is available online through the Minnesota Agricultural Experiment Station website at http://www.maes.umn.edu/. A limited number of print copies will be available through the University of Minnesota Extension Store at http://shop.extension.umn.edu or by calling 1-800-876-8636. A limited supply of print copies may also be available at your local U of MN County Extension Office.

Tips for Planting Winter Wheat Late

2012-09-17T18:35:08Z

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

2012-07-18T21:25:05Z

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

2012-07-10T20:16:24Z

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

2012-07-02T22:08:00Z

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.

2012-07-02T20:47:52Z

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

2012-06-25T21:46:16Z

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

2012-06-14T22:04:20Z

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

2012-06-05T15:58:57Z

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.

Crop Water Usage, Available Soil Moisture and Irrigation for Small Grains.

2012-06-05T15:50:51Z

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 by Checkbook Method Extension bulletin from the University of Minnesota Extension.