Skip to main content


Showing posts from 2009

Tillage Considerations for Wet Soil Following a Late Harvest

By Jodi DeJong-Hughes and Jeff Coulter
With the heavy precipitation across most of Minnesota this fall, harvest has been challenging. Not only are farmers scratching their heads about how they are going to get in the field to harvest, but they are wondering when they will have time to complete the fall tillage. This article will address options for tillage in wet soils.

Lodging in Corn: Diagnosis, Harvesting Tips and Unexpected Damage in Triple-Stack Corn

by Ken Ostlie, Extension entomologist
Problems with lodging in field corn have been reported across Minnesota. Goose-necked or falling stalks from a variety of causes can complicate harvest and lengthen harvesting times. With earlier rainy and snowy weather already delaying harvest, growers can ill afford the surprise of unexpected lodging in their fields. Occasional damage from corn rootworms in triple-stack corn has also occurred. Now is the time to assess how well fields are standing, adjust harvesting priorities and investigate the causes behind unexpectedly lodged corn.

Pre-Harvest Considerations for Corn

By Ryan Van Roekel, Research Assistant and Jeff Coulter, Extension Corn Agronomist
Combine Adjustment
With the 2009 growing season winding down, now is the time to prepare for corn harvest and start thinking about next year. Volunteer corn in soybean fields serves as a reminder to properly adjust combines. In addition to being an eyesore, volunteer corn can cause significant economical losses through added weed control costs and lost bushels at harvest. It only takes two corn kernels on the ground per square foot to equal one bushel per acre (Carlson and Clay, 2002), and that's not to mention dropped whole and partial ears that contain hundreds kernels. For specific suggestions on combine adjustment, see the article from Mark Hanna of Iowa State University:

HRSW Varieties with a Higher Risk of Preharvest Sprouting

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
VarietyPreharvest Sprouting Rating1Bigg Red4Blade5Granger4Hat Trick4Sabin4Samson4Traverse411=best, 9=worst

Harvest Strategies to Optimize Corn Silage Quality and Yield

By Jeff Coulter, Extension Corn Agronomist
With the majority of the Minnesota corn crop in the milk stage (Figures 1 and 2), now is a great time to begin planning for corn silage harvest. Proper harvest management is critical for high quality silage, and it starts with harvest timing. This ensures that the harvested crop is at the optimum moisture for packing and fermentation. Silage that is too wet may not ferment properly and can lose nutrients through seepage. If silage is too dry when harvested, it has lower digestibility because of harder kernels and more lignified stover. In addition, dry silage does not pack as well, thus increasing the potential for air pockets and mold.

Soybean Growth Stages for Pest Management Decisions

by Phillip Glogoza, Extension Educator, Crops

Management decisions on whether to treat soybean aphids will be affected by the soybean growth stage in a field during the next two weeks. As plants progress to the later reproductive stages (e.g., R5, R6, R7, etc.) risk of yield loss from aphids declines. Currently, the soybean crop ranges from R3 to R5. Insecticide treatments for R5 stage soybeans may respond positively to soybean aphid treatments when populations exceed threshold, however the level of the yield response is less predictable. Early R5 treatments are more likely to realize a positive response than late R5 treatments. Treatments for aphids are generally not recommended beyond the R6 growth stage.

New spider mite fact sheet

By Ken Ostlie and Bruce Potter

Reports of spider mite infestations continue from both soybean and corn, particularly from areas with prolonged drought.  Even if you've received rain recently, check for mite activity along field edges to determine if you've got a building problem.  You may need to factor spider mites into a soybean aphid spray decision.

The article is available on the web at:

Well so much for the relatively arthropod pest- free growing season.

A Comparison Of Aphid and Disease Management Practices in Soybeans

by Dr. Ian MacRae, U of MN Extension Entomologist
There has been increasing pressure to apply insecticide and tank mixed pesticides at lower thresholds based on claims of increased yield benefits. While increased commodity prices can stimulate the desire to decrease risk tolerance and increase the use of pesticides, this is not always a paying proposition.

The current treatment treatment threshold for soybean aphids (250/plant when most plants have aphids) has been adopted and is recommended by the Extension services of all of the soybean producing states in the North Central region. It is the result of many site-years of data collected from field plots mirroring commercial; production. It incorporates data from a variety of geographic locations, climate conditions, commodity prices and management costs. Most importantly, at the treatment threshold, NO economic injury is yet occurring!

Time to Scout Soybean Aphids - They've Finally Arrived in the North

by Dr. Ian MacRae, U of MN Extension Entomologist
Low populations of Soybean Aphid (SBA) have been reported throughout NW MN and NE ND. Populations are still low and generally not on more than 30% of the plants. The cooler weather will slow reproduction for a few days but it is predicted to warm up by the weekend, at which time we'll start to see some more population growth and dispersal across fields. Although most fields are well below treatment levels so far, it is time to start scouting the soybean fields, getting a handle on what populations you may have and tracking progress and population growth.

Final Words of Caution on Wheat Midge

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).

Now is an important time to do some evening scouting and become aware of any activity in your fields. Find out now . . . Not at harvest time!

Sunflower Rust is Widespread but Developing Slowly

by Dr. Charla Hollingsworth, U of MN Extension Plant Pathologist
Early lifecycle stage structures (pycnia) of sunflower rust were detected on volunteer sunflowers during early-June in Minnesota and North Dakota (Figure 1). These detections created concern because that meant: The fungus was only two spore stages away from producing the spores responsible for epidemics (pycnia → aeciospores → urediospores); it was much too early in the growing season to see rust developing; and the fungus had overwintered in our agroecosystem in its sexual stage. A possible outcome of winter survival is the potential for genetic recombination by the pathogen where more virulence might occur on sunflower varieties grown here.

Weed Control in Roundup Ready Sugarbeet

by Dr. Jeff Stachler, Sugar beet Weed Scientist
U of MN Extension / NDSU Extension

For those growers unable to apply glyphosate to Roundup Ready sugarbeet for the first time due to wet soil conditions, apply the maximum rate of glyphosate allowed. The maximum glyphosate rate for Roundup Ready sugarbeet is 1.125 pounds acid equivalent per acre (lbs ae/A). This equates to 32 fluid ounces per acre (fl oz/A) of Roundup-branded products, 48 fl oz/A of 3.0 pounds acid equivalent per gallon (lbs ae/gal) products, and 39 fl oz/A of 3.7 lbs ae/gal products. This glyphosate rate can only be applied up to the eight-leaf stage of sugarbeet. This rate should be applied to any field with weeds greater than two to three inches in height or with difficult to control species such as wild buckwheat, lambsquarters, and common and giant ragweed.

Watch for Midge as Wheat Approaches Heading Stage

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.

Based on degree day accumulations, wheat midge should be emerging in the southern counties of the spring and durum wheat region (Figure 2). The oldest wheat fields have begun heading. Midge should begin emerging in the central areas over the weekend, and by the middle of next week in the northern areas.

Aphids in Small Grains - June 29, 2009

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

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

Jochum Wiersma, Samll grains specialist
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.

Soybean Rust: What will this year bring?

by Phillip Glogoza, Extension Educator - Crops
Soybean rust was found in 392 counties in the United States in 2008. This is the highest number of counties reporting the disease since it was first discovered in the continental U.S. in 2004. Soybean growers in Alabama were encouraged to use fungicides on at risk beans in late August, many neighboring states reported mostly low infection levels throughout the month of September as the crop matured.

Alfalfa Weevil: Coming on Strong in West Central MN

by Doug Holen, Extension Educator - Crops, Fergus Falls
and Phillip Glogoza, Extension Educator - Crops, Moorhead
Just a quick note to report a significant outbreak of alfalfa weevil in WC MN. It escalated over the weekend with a lot of spraying starting on Monday. We have fields in all stages with 1st crop still standing, cut alfalfa in windrow for some time, and 16" of 2nd crop regrowth. All fields have been hit hard. All alfalfa growers in west central MN should be checking for possible infestations.

Consider Narrow Rows for Higher Corn Yields in West-Central and Northwest Minnesota

By Jeff Coulter, Extension Corn Agronomist; and Lizabeth Stahl, Extension Educator - Crops
Now is a great time to consider modifications to your corn production system for 2010. A key step to higher corn yields may be narrow rows (narrower than 30 inches). Planting corn in narrow rows increases the within-row distance between plants, which in theory helps minimize competition among plants for water, nutrients, and light. This is particularly true in the northern Corn Belt, where the shorter growing season and cooler air temperatures can limit crop yield potential. For corn growers contemplating narrow rows, consider the following.

Sunflower Rust Fungus is Alive and Well in Minnesota and North Dakota

By Dr. Charla Hollingsworth, Plant Pathologist, U of Minnesota Extension
and Dr. Sam Markell, Plant Pathologist, NDSU Extension Service

This past week, the fungus that causes rust on sunflower, Puccinia helianthi, was identified on wild and volunteer sunflowers in Minnesota and North Dakota. The rust fungus is known as a "macrocyclic" pathogen because it produces five successive types of spores during its lifecycle. While all five types of spores are produced on sunflower, only one type is responsible for causing rust epidemics.

Wireworms in Small Grains

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.

Controlling Canada thistle with Milestone

By Carlyle Holen, IPM Specialist, U of Minnesota Extension
What is the optimum time to treat Canada thistle (Figure 1) in non-cropland with Milestone? Based on field trials at Ada in 2007 the window for application is pretty wide and perhaps a better way to frame the question might be: What is the least effective time to treat Canada thistle?

Cool Temperatures Delay Alfalfa Weevil: Time to Scout Fields in NW MN

By Phillip Glogoza, Extension Educator - Crops

The cool temperatures have delayed alfalfa weevil population development in the region. In west central MN, first cut got underway two weeks ago. As we move northwest, first cut may just be beginning for some. In some cases, cutting alfalfa may have removed significant eggs laid in stems, while in other sites young larvae are feeding in the growing terminals, whether it is regrowth or uncut alfalfa.

Causes of Seedling Stand Losses in Spring Wheat

Jochum Wiersma, Small grains specialist
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.

Continuous Corn in Minnesota: How do we do it?

by Ryan Miller and Brad Carlson, Extension Educators – Crops
In 2008 University of Minnesota Extension launched an on farm research project evaluating continuous corn production under a series of different tillage systems on six farms across Minnesota. For the sake of brevity this article will only address one site in Southeastern Minnesota that is located near Faribault.

The tillage systems studied include a conventional moldboard plow system, a chisel plow system representing a traditional conservation tillage, and strip till as a higher residue conservation tillage system.

Now is The Time to Evaluate Stands

Jochum Wiersma, Small grains specialist
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.

Stand counts are simple to do and take just a little extra effort while you are scouting for weeds and/or early season fungal diseases. The easiest time to do a stand count is probably when the crop is in the two- to three-leaf stage since tillers are not visible yet, and counting is easier.

Glyphosate nonperformance issues and glyphosate-resistant biotypes

Glyphosate-resistant biotypes of giant and common ragweed and common waterhemp have been confirmed in Minnesota and are listed on the International Survey of Resistant Weeds web site at: Both species appear to be resistant to approximately four-times the labeled use rate of glyphosate (4X).

In the short time frame presented to us during the growing season, separating glyphosate nonperformance due to resistant weed biotypes from other factors is an inexact and qualitative process but a quick response could help reduce the spread of glyphosate resistant weeds and set-up long-term management plans.

Temperatures Affect Glyphosate Activity

Temperatures over the last month have fluctuated greatly. Cold temperatures two weeks ago caused a reduction in glyphosate activity. Individual plants of lambsquarters and annual smartweed species where not completely controlled at a research location while other plants and other species were completely controlled. Cold weather in early June of 2008 also caused a reduction in glyphosate activity. The cold weather last week and early this week will likely cause glyphosate applications to be less effective until warmer temperatures persist.

Soybean Planting Date and Delayed Planting

We are into the fourth year of a soybean date planting trial at Crookston investigating how two different relative maturity soybean varieties respond to planting date. Results for 2006 - 2008 show maximum soybean yield when planting in the May 1 - 15th window of opportunity. Previous planting date trials from the University of Minnesota also show an optimum planting window of May 10 - 20 to achieve maximum yield (Table 1).

Orange Wheat Blossom Midge: Vigilance is in order

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.

Volunteer Corn Management in Corn and Soybean

Large populations of volunteer corn are being reported in some fields in Minnesota this year. What impact the volunteer corn will have on this year’s crop yield and the viable management options available will depend upon in which crop the volunteer corn is present. Making the assumptions that the majority of the volunteer corn present is glyphosate resistant and that glyphosate resistant crops were planted in the field this year, your only management option in corn at this time is cultivation. In soybean you have the herbicide options of the ACCase inhibiting herbicides such as: Select Max (clethodim), Fusilade DX (fluazifop-P), Fusion (fluazifop-P & fenoxaprop) and Assure II (quizalofop); note Poast Plus (sethoxydim) is not as active as the other herbicides on volunteer corn. The ACCase inhibiting herbicides are generally targeted on 12- to 24-inch tall volunteer corn. The ALS herbicide, Raptor can also effectively control smaller (2 to 8 inch) volunteer corn.

Blending of Wheat Varieties - II

Jochum Wiersma, Small grains specialist
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.

When blending two different hard red spring wheat cultivars, you will be able to market the harvested grain as one of your classes of hard red spring wheat defined by the U.S. Grain Grading Standards.

Many winter wheat stands were damaged as a result of the cold winter or the water and flooding this spring. Consequently, many producers have opted to reseed the damaged portions of winter wheat fields with spring wheat. In many cases this resulted in spring wheat being interseeded with winter wheat.

Rusts are Diseases of Economic Concern on Regionally-Produced Oat Crop

Charla Hollingsworth, UM Extension Plant Pathologist, and Jeff Stein, South Dakota State University Plant Pathologist
Crown rust (caused by Puccinia coronata var avenae) and stem rust (caused by Puccinia graminis f.sp. avenae) are widespread and common on oat in the North Central (NC) state region. If environmental conditions promote rust development on susceptible hosts prior to grain fill, significant crop losses are likely to occur. While both diseases are responsible for repeated losses in oat, crown rust has a history of being the most damaging in this region because epidemics occur with more regularity.

Seeding Rates in Hard Red Spring Wheat

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.

Repeated research, however, has demonstrated that the optimum seeding rates differ for individual varieties. To determine this optimum seeding rate the variety in question is tested at a wide range of seeding rates. The seeding rate for maximum grain yield can be derived from the parabolic response curve of grain yield versus number of plants pe…

Fungicide for corn? The influence of agronomic factors in 2008

Jeff Coulter, Extension Corn Agronomist
In the past few years, the use of foliar fungicide on corn has gained considerable attention. In 2008, with generous support from the Minnesota Corn Growers Association and BASF, research was conducted in southern Minnesota at Lamberton and Waseca to determine how planting date impacted corn response to foliar fungicide. In these trials, corn followed soybean at 32,400 plants per acre, and the hybrid was DKC52-59. At both locations, there was little to no foliar disease at the time of fungicide application. The same was true at the early dent stage, regardless of whether fungicide was used. Nonetheless, yield was generally 3 to 4% (5 to 6 bushels per acre) higher when fungicide was applied, regardless of planting date or location (Figures 1 and 2). The exception was the early planting date at Waseca, where foliar fungicide resulted in a 6% yield increase (Figure 1). However, these numerical yield increases were not statistically significant, eve…

Think Carefully About Corn Plant Population to Maximize Profits

Jeff Coulter, Extension Corn Agronomist
Field work is just around the corner, and now is the time to re-evaluate agronomic decisions related to corn planting. With support from the Minnesota Corn Growers Association and others, we have been able to conduct a number of trials to determine how corn yield responds to plant population for various situations in Minnesota.

In 2008, research was conducted at Lamberton and Waseca, MN to determine how planting date impacted optimum plant population. In this study, the economically optimum plant population was not consistently influenced by planting date (Figure 1). However, yield potential was greatest with early planting, and the optimum plant population with the early planting date was 2,400 plants per acre higher than that with the mid-May planting.