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Recently in the Climate and Weather Category

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.

By Robert Koch, Extension Entomologist

Recent cool and wet conditions may increase the risk of seedcorn maggot infestation in some soybean and corn fields. Seedcorn maggots are small (1/4 inch long), white maggots (fly larvae) that feed on germinating seeds. The maggots can tunnel into seed, which may result in seed death, and can injure the emerging plant tissues, which can affect plant growth or lead to damping off. Such injury can result in stand loss or weakened plants. For example, if the growing point of soybean is killed, "Y-plants" can result when branching develops at the cotyledons. Yield from "Y-plants" may be reduced if competing with neighboring healthy plants. Seedcorn maggot injury can be difficult to distinguish from other problems such as Pythium and other seedling diseases.
Fields at greatest risk are those with decaying organic matter, such as a recently incorporated cover crop or manure. Risk of injury is greater when cool and wet conditions slow germination and emergence, which increases the window of time plants are susceptible to attack. Rescue treatments are not available for this pest. However, preventative tactics can be utilized to protect seed and plants in high-risk situations. Seed-applied and soil insecticides can offer effective protection of germinating plants from seedcorn maggot (be sure to follow instructions on product label). In addition, degree-day models are available to guide decisions about adjusting planting date to avoid periods with high larval abundance (UW seedcorn maggot degree-days).
When significant stand loss occurs, replanting may be required, but this option should be considered carefully. Information is available to guide replant decisions in soybean (U of MN Extension soybean replant guide) and corn (U of MN Extension corn replant guide).

by M. Scott Wells - Forage and Cropping System Agronomist

Being new to this state, I have been curious about how this spring compares to the previous year as it relates to precipitation. This time last year, much of Minnesota reported below normal precipitation (Figure 1a). However, across Southern Minnesota this year there has been greater than normal precipitation reported with some areas departing more than 6-inches from the normal (Figure 1b).

Screen Shot 2014-05-02 at 5.50.27 PM.pngFigure 1.Minnesota Monthly Departure from Normal Precipitation for April 2013 (a) and 2014 (b). NOAA - Advance Hydrological Prediction Services.

With the increase in precipitation this spring, coupled with cool temperatures, there could be greater risk of delayed corn planting. Like many of you, we at the University are waiting for the soil to dry and warm so that we can plant research crops. Across the Midwest, several states report less than 20% of their corn acreage planted. In Minnesota, only 4% of the corn has been planted which is similar to the spring of 2013 (Figure 2). Unfortunately, judging the weather report for the next few days, it doesn't look like there will be a significant jump in corn acreage planted.

Screen Shot 2014-05-02 at 6.17.47 PM.pngFigure 2. USDA's weekly crop progress estimates of percentage of corn acreage planted as of April 28, 2014.

Last year, corn planting was delayed and forage producers were faced with significant loses of alfalfa acreage due to winterkill. During our winter workshops, forage producers asked where they could find cover crop seed to plant as forages. Questions arose as to which cover crop species and seeding rates were most appropriate to use along with where to source the seed. Many producers commented that they were not able to find cover crop seed last year, even though there were seed suppliers in Minnesota that did have inventory last spring. Below is a list of seed suppliers in Minnesota that carry cover crop seeds along with information concerning planting date and seeding rates. The below list is meant to assist producers interested in planting cover crops, however, it is not comprehensive or endorsed by University of Minnesota Extension Forage Program. Additional information on prevent to plant cover crop options can be found at University of Minnesota Forages Extension website.

Albert Lea Seeds Albert Lea, MN 800-352-5247
Agassiz Seed & Supply West Fargo, ND 701-282-8118
Central Sota Buffalo, MN 763-682-1464
Cover Crop Solutions Robesania, PA 800-767-9441
Federated Coop Several Locations
FMX Turf Castle Rock, MN 651-463-8041
La Crosse Forage & Turf Seed, LLC La Crosse, WI 800-328-1909
Legacy Seeds, Inc. Scandinavia, WI 866-791-6390
Marty's Farm Service Several Locations
Millborn Seeds Brookings, SD 888-498-7333
Prairie Restorations Several Locations
Producer's Choice Seed Jordan, MN 877-560-5181
Shady Knoll Farm Redwood Falls, MN 507-640-0993
Waconia Farm Supply Waconia, MN 952-442-2126
Welter Seed and Honey Co. Onslow, IA 563.485.2762
Werner Farm Seed Dundas, MN 507-645-7995

Hopefully, May brings flowers and favorable planting conditions.

2014 Extension Drainage Design Workshops

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The annual Extension Drainage Design Workshops will be held in four locations in 2014: January 29 - 30, SDSU Extension Regional Center, Sioux Falls, SD; February 11 - 12, North Dakota State College of Science, Wahpeton, ND; March 5 - 6, University of Minnesota - Crookston, Crookston, MN, and March 18 - 19, Holiday Inn, Owatonna, MN. The workshops are a collaborative effort between the University of Minnesota, North Dakota State University, and South Dakota State University Extension.

The 2-day workshops start at 8:00 a.m. and end at 5:00 p.m. on day two. The workshops will focus on planning and design of agricultural tile drainage systems to meet both profitability and environmental objectives. The course content is taught in a hands-on manner with lots of discussion time.

Each workshop is intended for those interested in a more complete understanding of the planning and design principles and practices for drainage and water table management systems, including: farmers, landowners, consultants, drainage contractors, government agency staff and water resource managers. Planning topics include legal aspects, basics of drainable soils, agronomic perspectives, doing your own tiling, land evaluation tools, wetlands, and conservation drainage concepts and techniques. The design topics begin with basic design considerations and progress through individual small team projects, with several hands-on problem-solving examples covering basic design and layout principles, water flow calculations, drain spacing, sizing, and grades. Design principles for lift stations and conservation drainage practices are also considered.

Registration for the four workshops sessions is now available at: The registration price is $225 (price goes up to $300 about 3 weeks before the start of each workshop), and each workshop is limited to about 65 participants. These workshops have typically filled quickly, so register early to guarantee a spot. Due to seating limitations, on-site registration will not be available on the day of the event. Detailed agendas and additional information will follow shortly and be posted to the registration site.

For more information contact Brad Carlson at, or visit

U of M Conservation Tillage Conference in St. Cloud, Feb 18-19

How-to information, expert advice, practical tips

By Jodi DeJong-Hughes, Extension Educator - Crops and Conservation Tillage Conference Coordinator


Roll up your sleeves for some practical, hands-on information that will save you soil, time, fuel -- and money. Conservation tillage is the focus of the ninth annual University of Minnesota Extension Conservation Tillage Conference and trade show Feb. 17 and 18, at the Holiday Inn and Suites, St. Cloud, MN. This conference emphasizes proven farmer experience and applied science. Straight from the trenches, learn how heavier, colder soils aren't necessarily the challenge they're made out to be. And, what have long-time no-tillers and reduced-tillage farmers learned that could spare you the same lessons?

John A. Lamb
Nutrient Management Extension Specialist
University of Minnesota

Because of weather, a number of acres of the 2013 sugar beet crop will not be harvested.  It has been a number of years (PIK years) since this many acres have been left un-harvested.  At that time, SMBSC and the University of Minnesota did conduct a number of research studies to answer the main production question:  "What should I do with these fields for next year?" 

By Daniel Kaiser
Fabian Fernandez
John Lamb
Carl Rosen

University of Minnesota Extension Nutrient Management Specialists

The increase number of acres planted to cover crops has raised questions on nitrogen (N) crediting for the 2014 cropping year.  While there are many benefits touted for the use of cover crops, there are a lot of unknowns when determining N credits.  This is especially true for mixes with multiple plant species. 

By Daniel Kaiser and John Lamb
Extension Soil Fertility Specialists

Many of our earlier planted fields in Minnesota have been exhibiting some significant variation in plant growth and yellowing this spring.  Our conditions in May and early June have been less than favorable for corn growth and for the release of nutrients from organic matter.  Due to the heavy rains nitrogen loss is being increasingly questioned and the decision of whether to side-dress or not will need to be made sooner or later.  There are a few considerations to make when deciding if more nitrogen should be applied.

Snow, rain, mud, now what?

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crop news late plant  pic 4.jpg

The weather has put us in a bind. Significant amounts of planting have yet to be completed, which has led to questions on the "correct" course of action. There will be no one "correct" course of action and with fields unsuitable for planting and more rain in the forecast there will be no easy decisions. One choice could be to utilize prevented planting, a choice that is appropriate for some and will lead to many other decisions to be made. A second option is to switch corn acres to soybeans; this may also be a wise and appropriate decision for some acres. Remember when planting soybeans after June 10th it is generally recommended to drop 0.5 RM from your typical full season varieties. The final choice is to stay the course and plant corn, a perfectly viable option for some acres.
A full set of delayed planting resources can be found at:

By Daniel Kaiser

Extension Soil Fertility Specialist

With the variation in conditions we have seen this spring there are a few issues that may show up in fields related to cool and wet soils. Purpling of corn leaves due to phosphorus (P) deficiency and early season interveinal striping due to sulfur (S) may occur if temperatures remain cool and we continue to have frequent rains. I want to take some time and outline these issues and some of the related research that has been conducted in the past five years.

By Daniel Kaiser

University Extension Soil Fertility Specialist

With the extreme variability in growing conditions there have been some questions regarding the variability in soil test. A project is being launched to establish a series of sentinel plots to study the monthly variation in soil test values over the next two growing season. We are looking for participants that are willing to take samples from a single point within a field and mail them off to us at Saint Paul. The goal of this study is to gain a better understanding of what is happening over the growing season for a number of different nutrients commonly measured.

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.

Relief spelled R-A-I-N for some

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Dan Martens, Extension educator,

Rain during the last week to 10 days provided some relief to some crops through central Minnesota in various amounts. Crops are at a lot of different stages. Some scorched corn crop may not benefit much from rain anymore. Pollination may have been hurt for some corn. There is a large amount of corn, soybeans and hay crops that will benefit significantly from recent rains.

Where crops are starting to deteriorate, like corn turning brown, some farmers might think about saving some other stored feed and starting to chop some of this corn. For anything you might do with the crop, for those carrying crop insurance, have a good discussion on with your crop insurance rep first.

For day to day feeding I'd think about the following:

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.

John A. Lamb and Daniel E. Kaiser
Soil Fertility Specialists

Nitrogen is important for corn growth. This has been a concern on growers' minds since March. First concern was with the poor tillage conditions last fall. Did the nitrogen applied stay in the soil. We attempted to answer that question in a March 18 E-news. At the time of that E-news, drought was the weather condition on everyone's mind. Now with the record rainfalls, there are concerns if nitrogen has been lost to leaching or denitrification.

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.

Table 1 Planting Time.jpg

By Gary A. Hachfeld, University of Minnesota Extension Educator, Ag Business Management

The early season frost in September caught many of us off guard. Damage to crops varied statewide but the fundamental question is, as a farmer, what should I do regarding a potential loss regarding my federal crop insurance? There are some basic procedures that one needs to follow in the event of a crop loss regardless of cause. This article outlines some of those procedures.

Following an early frost, it is very common for a farmer to utilize a given crop, such as corn, for an alternative use. That is, the corn was insured as grain and intended to be used as grain but due to the early frost, the farmer decides to chop the corn for silage. This could be the case for a number of crops. If this occurs, the farmer must contact their crop insurance agent before they begin to chop the crop for silage, a use other than what was intended. A crop insurance adjuster must evaluate the crop before harvest begins. If the adjuster cannot view the crop in a timely fashion, the farmer can go ahead and chop the field but they must leave a number of check strips for the adjuster to view at a later time. If a farmer decides to use a crop for something other than its intended use, always contact the insurance agent prior to harvest.

Soybean Yield Loss Estimates from Early Frost
Seth Naeve - Extension Soybean Agronomist

Few resources are available to producers and agricultural professionals relative to yield losses from late- season frost injury to soybean plants. A study investigating the risks and benefits of long-season soybean varieties was established in 2008. This work was carried out by the Naeve Soybean Production Project, and was funded by the Minnesota Soybean Research & Promotion Council. While we don't have all of the answers that folks search for after a late-season frost, a small piece of this research effort is described below.

In 2009, 2010, and 2011 soybean plots were established to investigate the yield effects of early frost on a range of soybean maturities. Three varieties with maturities of RM 0.8, 2.0, and 2.8 were examined in 2009. These were planted at a normal seeding date (around May 1) and at a late planting date (around May 21). Frost was simulated with applications of Liberty herbicide at a rate of 32oz per acre in 10 gallons of water on September 7 (early) or September 21 (late). In 2010 and 2011, five varieties ranging from MG 0.8 to 2.8 were planted at a single planting date (early May) and treated to simulate frost on three dates (approximately September 7, 14, and 21).

field shot.jpg

Photo of a soybean plot 'frosted' with Liberty approximately 10 days prior. In the left of the photo is a soybean plot 'frosted' 3 days prior.

Frost and Freezing Temperature Effects on Soybeans

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By Seth Naeve and Dave Nicolai University of Minnesota Extension

A hard frost occurred early Thursday morning (Sept 15th) across much of central and southern Minnesota.  The complete effects of this frost or freeze event may not be known for some time.  However, most soybean and corn fields have not reached physiological maturity.  Yield and quality in these fields were likely affected. 


By Gary Hachfeld, University of Minnesota Extension
Originally published in Ag News Wire

Farmers who are prevented from planting their crops due to wet spring weather can manage this risk if they have purchased federal crop insurance.

Yield protection, Revenue Protection and Revenue Protection with Harvest Price Exclusion policies all include prevented-planting coverage. There is no prevented-planting coverage with Group Risk Plan or Group Risk Income Protection insurance.

By federal definition, prevented planting is failure to plant the insured crop with the proper equipment by the final planting date designated in the insurance policy. Final planting dates vary by crop and by area. For example, the final planting dates are generally May 31 for corn, June 10 for soybeans, and May 15 to June 5 for wheat, depending on location. Farmers should check with their insurance agent if they have questions on the final planting date.

Farmers who have had an insurance policy in the past are eligible for prevented-planting coverage. New policyholders are also eligible if their loss occurred after the sales closing date and all other prevented-planting requirements are met.

If a farmer is prevented from planting a crop by the final planting date, there are several choices. Those choices include:

  1. Plant the crop during the late planting period, which is generally 25 days after the final planting date. There is a reduction per day in coverage using this choice.
  2. Plant the crop after the late planting period with no reduction in the insurance coverage.
  3. Leave the acreage unplanted and receive a full prevented-planting payment.
  4. Plant a cover crop and receive a full prevented-planting payment and graze or hay the crop after November 1.
  5. Plant another crop (not the insured crop) after the late planting period or after the final planting date if no late planting period applies. Hay or graze a cover crop, but not before November 1, and receive 35 percent of the prevented-planting guarantee.

There are many provisions included in the prevented-planting provision of federal crop insurance. Keep good records and documentation. When in doubt, read your crop insurance policy or contact your crop insurance agent. Any small infraction of any of the provisions can result in no indemnity payment and loss of the crop insurance protection you purchased.

See more on the late planting page.

Managing a late start to soybean planting

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By Dave Nicolai and Seth Naeve
Originally published in Ag News Wire

With only 28 percent of corn acres planted prior to May 9 in Minnesota, growers face the difficult decision of when to begin planting soybeans in order to maintain adequate yields.

Soil conditions are of primary importance when considering delayed planting.

Soil conditions and soil temperature

Soil conditions at and after planting usually make a difference in how successfully the crop is established. Soil compaction and smearing is a concern when pulling implements and the planter through, or driving on, wet soil.

To limit soil compaction, keep axle loads under 10 tons and properly maintain air pressure in the tires. Not only does this help the soil, but it will help your tractor run more efficiently and with less slippage. On wet soils, use the lightest tractor that can get the job done.

Soybean has delicate seed, so it benefits when planted about 1 1/2 inches deep, modestly firmed into the seed furrow, covered by relatively loose soil, and into soils with temperatures of 60 to 70 degrees. As of May 9 , soil temperatures at the 2-inch depth averaged 61 and 56 degrees, respectively, at University of Minnesota Research and Outreach centers in Lamberton and Waseca.

The lack of oxygen in saturated soils and the formation of a soil crust of even modest strength can almost eliminate soybean emergence. Therefore, it is important to pay attention to the five-day forecast prior to planting. Planting in cool and wet conditions may lead to poor germination and seedling diseases such as pythium. These problems are magnified by extended cold and rainy periods after planting.

University of Minnesota Extension research indicates that, under ideal conditions, soybeans in southern Minnesota should be planted at about 140,000 live seeds per acre (see Table 1). Soybeans grown in central and northwestern Minnesota require harvest stands of approximately 125,000 to 150,000 plants per acre to maximize yields. This is likely due to shorter-statured soybeans with fewer total nodes that are often produced in these regions. Increased seeding rates are required in central and northwestern Minnesota.

Table 1
Maturity group II soybeans 140,000 live seeds per acre
Maturity group I soybeans 150,000 live seeds per acre
Maturity group 0 soybeans 160,000 live seeds per acre
Maturity group 00 soybeans 170,000 live seeds per acre

Planting date and soybean yield

Since early-May plantings usually result in maximum yields, lower yields should be expected for later plantings (see Table 2). Planting soybeans in Minnesota on May 10 results in only a 2-percent yield loss; on May 15 in a 3-percent yield loss, and on May 20 in a 6-percent yield loss (or 94 percent of normal yield).

Table 2
Planting date Yield loss (%) Yield potential (%)
May 1 0 100
May 5 1 99
May 10 2 98
May 15 3 97
May 20 6 94
May 25 9 91
May 30 13 87
June 4 18 82
June 9 24 76
June 14 30 70

For more educational information and tools, visit, a cooperative effort among the University of Minnesota, University of Minnesota Extension, and the Minnesota Soybean Research and Promotion Council. More information about delayed crop planting can be found at

By Daniel Kaiser
Extension Soil Fertility Specialist

With the recent flooding or late season hail there may be questions on whether a credit can be taken from soybeans not harvested for the next year's crop. Soybeans are a high protein crop which means they can contain a large amount of nitrogen. Average vaules of nitrogen removed in soybean grain are reported at around 3.8 lbs of N per bushel (Source IPNI) for a total of 190 lbs of N in a 50 bu/ac soybean crop. In comparison corn grain would remove about 0.90 lbs of N per bushel and a total of 180 lbs of N in a 200 bu/ac crop.  Can all of this nitrogen be counted on if the soybeans cannot be harvested and are plowed under if they cannot be harvested?  

Dean Malvick
Extension Plant Pathologist
Not only have the hot and dry conditions and hail affected corn yields in Minnesota this year, these conditions have also favored development of ear rots. Reports of ear rots have been coming in from several different areas, and the quality of grain that comes off these affected fields may be reduced. Several different types of ear rots occur in Minnesota, and all are not equally important. Aspergillus ear rot and Fusarium ear rot may be of particular importance this year due to the hot and dry conditions in much of Minnesota.

by Mark Seeley, Extension Climatologist

Frost / freeze analyzed maps available

Last weekend (May 8-9) brought widespread overnight frosts and freezes to many parts of Minnesota. Reports indicate that some fruits and crops were damaged, especially in low-lying areas, but many may recover. Further, it appears this may be the last frost occurrence for the season over most of the state, as a significant warming trend is expected to start this weekend.

As is often the case many growers and crop advisors are concerned about assessing any damage due to these low temperatures (primarily 27-32 degrees F), but patience is required. It always takes a few days to sort out which areas might be permanently killed, as many plants, depending on stage of development are resilient and begin regrowth within a week.

The Minnesota Climatology Working Group offers daily analyzed maps to examine the spatial extent of frosts and freezes.

For those interested in storm spotter training

For Minnesota citizens who are interested in becoming storm spotters for the National Weather Service, SKYWARN spotter training classes will be offered free of charge during the month of May on eight different occasions. National Weather Service also encourages citizens to become involved in the eSpotter System which supplements information about storm location, intensity, and aftermath damage assessment. If you are interested in these programs or the free training sessions you can visit the web site.

Wind and Hail Damage to Pollinating Corn

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Jeff Coulter, Extension Corn Agronomist

Strong winds and hail on July 31 affected numerous corn fields throughout southern and central Minnesota (Figs. 1 and 2). Damage included loss of leaf area and stem bruising from hail stones, along with root lodging and stalk breakage from high winds. When the damage occurred, tassels were just starting to become visible in some fields, while pollination was partially or completely finished in other fields.

Dave Nicolai, Regional Extension Educator-Crops, Hutchinson, MN
Dale Hicks, University of Minnesota Extension Corn Specialist

Some of the severe lodging from last week's tornado and wind storm occurred in fields not yet mature. Severely damaged immature corn will likely shut down prematurely (kernel black layer development). If silage is an option, obviously that would be a preferred choice for utilizing immature corn that is severely flattened.

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).

Mark Seeley
Extension Climatologist

As we have been hearing the cold growing season has exposed this year's corn and soybean crops to higher risk of frost damage and more importantly the likelihood of not maturing and being at high moisture content for harvest. Some have referred to their experiences with other similar growing seasons. These are climatically hard to find and not very many in number.

Please find below the ten coldest growing seasons at the University of Minnesota Southern Research and Outreach Center in Waseca, MN. This ranking is based on Growing Degree Days (GDD base 50/86 F) for the May 1 to August 30 period. Also listed are the following September GDD values and the first frost date of the designated year. The parenthetical values are the long term averages.

Year 5/1-8/30 GDD


Sept GDD

Frost Date

1915 1687 372 9/10
1917 1697 301 9/21
2004* 1775 ? ?
1967 1776 344 9/24
1924 1794 293 9/30
1945 1817 377 9/28
1927 1834 486 9/20
1992 1860 352 9/29
1979 1894 399 10/7
1968 1913 327 10/4
1966 1923 374 10/1

Please note that in almost all cases the combination of September GDD and later frost date did not materialize to make up for the slow crop development associated with fewer seasonal GDD accumulation. A warm, early September in 1927 produced above normal GDD values, but an early' frost occurred on the 20th. A warm September and later than normal frost in 1979 was offset by an extremely late plant date that year that did not allow the crops to reach maturation.

Mark Seeley
Extension Climatologist, University of Minnesota

On three consecutive mornings, August 19-21, record or near record low temperatures were reported around Minnesota. Some resulted in damaging ground frosts, while others resulted in a hard freeze, all but ending the growing season for some crops.

Some of the temperature reports included:

Thursday, August 19 th, new record low temperatures were reported from the following locations:

  • International Falls 36 F

  • Duluth 37 F

  • Little
    Falls 35 F

  • Tower 25 F

  • Orr 37 F

  • Embarrass
    27 F

  • La Crosse, WI 46 F

  • Olivia 37 F

  • Sioux Falls, SD 39 F

  • Willmar
    39 F

  • Fargo, ND 39 F

  • Pine River 37 F (tied)

  • Madison 36 F

  • Wadena 36 F

  • Crookston 37 F

  • Park
    Rapids 36 F

  • Thief River Falls 37

  • Waseca 40 F

Friday morning, August 20th brought even more frost to many sections of northern Minnesota. Numerous new record lows were set all around the state. Those locations reporting freezing temperatures or nearby ground frost conditions included the following:

  • International Falls 33 F

  • Cook 30 F

  • Hibbing 35

  • Pine River 34 F

  • Aitkin 32 F

  • Bemidji 35 F

  • Floodwood
    31 F

  • Littlefork 32 F

  • Babbitt 32 F

  • Kabetogama 33 F

  • Isabella 32 F

  • Tower 23 F

  • Embarrass
    23 F

  • Grand Forks, ND 32 F

  • Fargo, ND 34 F

  • Crookston
    32 F

  • Wadena 34 F

  • Hallock 30 F

  • Thief River Falls 30 F

  • Park Rapids 32 F

  • Baudette
    35 F

  • Brandon, Manitoba 32 F

And finally, on Saturday, August 21 st yet more freezing temperatures, ground frosts and new low temperature records were reported from the following:

  • Crookston 35 F

  • Karlstad 35 F

  • Red Lake 36 F

  • Int.
    Falls 32 F

  • Itasca 32 F

  • Hibbing 27 F

  • Park
    Rapids 35 F

  • Wadena 37 F

  • Grand Rapids 32 F

  • Montevideo 32 F

  • Milan 34 F

  • Madison 30 F

  • Morris
    35 F

  • St Cloud 33 F

  • Willmar 36 F

  • Olivia 36 F

  • Aitkin 35

  • Staples 33 F

  • Brainerd 32 F

  • Chaska 36 F

  • Lamberton 35 F

  • Worthington 36 F

  • Waseca
    37 F

  • Lakefield 37 F

  • Pipestone 36 F

  • Preston 35 F

  • Theilman
    35 F

  • Grand Meadow 35 F

Yes, we have had frequent intrusions of high latitude arctic air masses this summer thanks to the persistent position and strength of a continental polar vortex. This makes us all nervous about early frost probabilities for a very slow developing crop. Find below a chronology of August frosts reported south to north along the Red River Valley...

  • Ada, MN (3 years) 8/31/1895, 8/21/1920, and 8/30/1931
  • Crookston, MN (3 years) 8/28/1893, 8/13/1964, and 8/28/1965
  • Thief River Falls (3 years) 8/26/1915, 8/30/1930, and 8/27/1982
  • Argyle, MN (six years) 8/25/1934, 8/31/1935, 8/13/1964, 8/28/1965, 8/27/1982, and 8/27/1986
  • Hallock, MN (8 years) 8/29/1915, 8/21/1920, 8/24/1923, 8/23/1927, 8/28/1934, 8/31/1935, 8/18/1942, and 8/27/1982

So at least for northern counties there is certainly precedent for such temperatures in August, though they are unusual. In southern counties it is exceptionally rare to see freezing temperatures in August, though not entirely unseen in the climate record. Witness Pipestone had frost on August 11, 1902 and again on August 23, 1987.

Though the microclimate effect weighs heavily on the occurrence of frost, notice some common years for all.....the summers (May through August) of 1895, 1915, 1923, 1942, 1965, and 1982 were all in the colder end of the distribution historically, just as the summer of 2004 has been. Although we are expected to average a bit warmer than normal between now and the first week of September, the Climate Prediction Center forecasts a cooler than normal month of September for Minnesota. This translates to a high likelihood for immature crops of relatively high moisture content. The prospect of making up for lost Growing Degree Days (GDD) is dim. The table below summarizes the cumulative GDD for field corn (modified base 50/86 method) over a series of planting dates that is representative of the calendar window when most of the state's nearly 7 million acres of corn were sown this spring. The shortage of GDD is amplified by later planting dates since the growing season has essentially been consistently too cool to close the gap and draw GDD totals closer to normal. Many of the GDD totals remain over 20 percent behind normal.

Table 1. Modified Growing Degree Day Summary (Base 500/86 F) for the 2004 Crop Season, Covering Corn Planting Dates from April 20 to May 10.

GDD Total Since 4/20
Dep from Norm
GDD Total Since 4/30
Dep from Norm
GDD Total Since 5/10
Dep from Norm
Browns Valley
Fergus Falls
St. Cloud
Redwood Falls
Red Wing

The other feature of the September climate outlook worth mentioning is that Minnesota is expected to be wetter than normal. This may impinge on the ability of the crop to dry down before being harvested. So all the climatic indicators suggest that corn and soybean crops will not reach normal maturity, will likely be exposed to further frost or freeze damage, and will be of higher moisture content and require further drying. (Naturally, I hope I am wrong!)

Corn Lodging - What Can We Expect?

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Dale R. Hicks, Department of Agronomy and Plant Genetics, University of Minnesota

The extreme winds that occurred in southern Minnesota on August 3rd caused corn to lodge badly. Lodged plants will likely yield lower and make harvesting more difficult.

D.R. Hicks
Professor of Agronomy and Plant Genetics

Heat accumulation during the growing season can be used as a predictor of plant development. The very high temperatures we've had, especially the high night temperatures, have caused the Growing Degree Day accumulation to be slightly ahead of normal for most of the state. But corn development is still lagging so there is the question of how effective this temperature accumulation really is for corn development.

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