Friday, June 29, 2012

Preliminary Wheat Yield Results - Janesville, WI

Preliminary winter wheat yields at our Janesville, WI variety trial site have been averaging 85 bu per acre. Test weights have all been above 60 pounds with moisture ranges of 12 to 13%. The highest plot yield noted so far has been 108 bu per acre.

Sunday, June 24, 2012

Late-Season Weed Escapes in Wisconsin Corn and Soybean Fields

The potential increase of glyphosate-resistant weeds is a major threat to corn and soybean production across the Nation.  Integrated Weed Management tactics, including diversified herbicide use, are important components of management to delay the onset of glyphosate resistance.  Identifying geographies that may be most vulnerable to resistance development could help direct attention and pro-active resistance management tactics before wide-scale control failures occur.  To help with this, the University of Wisconsin-Madison Field Crops Weed Science Extension program is asking for your participation in a research study investigating the weed species diversity in Wisconsin Corn and Soybean fields due to reduced atrazine use and subsequent increased use of glyphosate. The purpose of this research is to identify areas in the state where there may be a shift to weeds that are more difficult to control with glyphosate, or where weeds that are resistant to glyphosate may first appear. 
This survey asks questions about target weed species and limited management history information relating to crop production fields. There are two levels of participation in this survey.  The first level simply includes filling out an on-line survey with information from ONLY ONE CROP PRODUCTION FIELD per survey form.  If you are willing to provide information about more than one field, please repeat the survey.  The second level of participation, if you would please participate further, is to allow weed science research staff from the University of Wisconsin-Madison to survey your crop fields for weed escapes in late-summer months. 

We expect the survey to take only 5 to 10 minutes of your time, and we don't anticipate any risks to you.  For fields we scout for weed escapes in the late summer, we will provide a detailed weed scouting report to participants.

You may ask questions about the research at any time by contacting Vince M. Davis at (608) 262-1392 or Ross Recker at  Your participation is completely voluntary.  By completing and electronically submitting this survey, you consent for participating in the first stage of the survey. If you would like to participate in the second stage, and allow UW weed science researcher to scout your production fields, please complete the last question of the survey by providing your contact information.

To complete the survey, please visit:

We THANK YOU in advance!  

Vince M. Davis, Extension Weed Scientist and Ross Recker, Graduate Research Assistant

Thursday, June 21, 2012

Early Season Water Deficit Stress on Southern WI Soybeans

I went to bed last night hoping this article would not have to be written, but that whopping 0.05 hundredths (or less) of rain we received across much of Southern WI last night forced the issue.  According to data from the 2012 Weather Summary for UW ARS - Arlington and Marshfield WI Locations (compiled by Dr. Joe Lauer) we are tracking over 4 inches behind the 30 year norm at Arlington (precipitation from April 1 to today). A similar trend was occurring at our Marshfield location until recent rainfalls brought us back to near 30 year norms. The implications of this water deficit on soybean are as follows.   

In soybean there are two growth periods for which soil moisture is critical for optimum growth and development: at planting and during the reproductive stages from bloom through pod fill.  The time period from stand establishment to bloom is not as critical.  Drought stress during this time period will often shorten internodes; however yield loss rarely occurs. Luckily most of the WI soybean crop is in the vegetative growth phases though bloom is beginning.  As stated above depleted soil moisture at planting can significantly impact the soybean crop. Therefore if this dry weather pattern continues growers should be very cautions about planting double cropping soybean into dry soil.

In Wisconsin the main reproductive growth in soybean occurs from early July to mid-September.  Soybean in this stage use about 1/4 to 1/3 inches of water per day.  Lack of sufficient water can cause flowers and young pods to abort reducing the number of seeds per plant (Image 1).  Also, soybean plants reduce the size of their leaf pore openings to reduce the loss of water vapor.  This also reduces the intake of carbon dioxide and the manufacturing of photosynthates which slows plant growth.  When normal soil moisture returns, normal growth is resumed.  This ability to reduce metabolic activity allows plants to tolerate dry spells without dying or harming their ability to resume growth when normal moisture returns.

Image 1. Pod abortion in soybean caused by drought stress.

 If a drought does develop and severely affects podset and seed fill, and if livestock feed is needed, soybeans can be harvested as a forage for ensiling.  Highest protein and yields are obtained from soybean harvested at the R6 to R7 growth stage.  Harvesting soybeans for forage between the R1 and R5 stage will result in very high quality silage, but dry matter yields will be reduced significantly.  Forage quality will be reduced from R5 soybean forward if a conditioning process is used during harvest.  Conditioning will cause significant seed shattering. 

Managing Drought-Stressed Soybeans in the Southeast.  North Carolina Cooperative Extension Service. 1999. 

Virginia Soybean Update. Virginia Agricultural Experiment Station. Volume 2, No. 4, July 1999.

Sunday, June 10, 2012

Cereal Leaf Beetle and Desiccated Soybean Seeds

Over the weekend two issues came to my attention:

1. It appears that cereal leaf beetle has hit threshold in a few fields. Dean Volenberg noted "Seeing high densities in some fields (5 per plant) and the flag leaf is about finished off.  It is hit or miss as far as scouting, one field will have them and the next is void of any larvae and adults.  Threshold at this stage of wheat is one Cereal Leaf Beetle per plant (NDSU Extension).
 Image 1. Cereal leaf beetle larvae and crop injury on oat. 
(Image from D. Volenberg)

 2. Also some late planted soybeans that were planted at the dry/wet soil threshold have imbibed water then desiccated. Please review my article entitled:  Variable Germination and Emergence in Soybean: Which Seeds Are Still Viable? for recommendations.

Addendum from Jim Specht (UNL):
Thought I would let you know that some Nebraska soybean producers have experienced the problem of germinating seed not having enough soil moisture to complete either the germination and/or emergence process because of two reasons.   

One reason is because they planted in dry soil and hoped for a rain, which is risky.  Some producers did get a hoped-for rain, but the rain amount was only enough to wet the soil down to where the seed was placed and not enough to connect that wet layer with the moist soil another inch or two below that seed.  As a result, the seeds germinated and the radicles emerged, but because roots will not penetrate a dry soil layer, the seedlings died because rooting systems were limited to using surface water, which ultimately dried out.  This scenario forced a replanting.  A second reason was because some producers have been using cover crops for some years now even though I warned them that cover crop use WILL be definitively detrimental in a dry spring.  We have had wet springs to date, which led producers to not think about the fact that while cover crops offer all the great stuff that extension specialists have promoted, they have ONE GIANT PROBLEM - unlike fallow which can only surface dry out in dry years, cover crops put roots into the soil and act like putting blotting paper in the soil, meaning that cover crops can transpire away the stored soil water!  Well, BINGO, we got a dry spring in Nebraska this year!  Cover crop users discovered the problem this year that I warned them about every time they discussed the advantages of cover crops.  One NE Soybean Board Member actually found out that his cover crop had dried out the soil to a depth of almost 10 inches, and when he only got sufficient rain to wet the seed, it was definitely not enough to connect the wet soil surface by wetting the soil down to a deeper down moister soil depth.  Consequently, his entire field of soybeans germinated, and then died.  What's worse for him, is that he still needed a drenching rain to eliminate that dry soil layer before he could even begin to think about replanting!  

Therefore, I have been re-urging all extension specialists in Nebraska to warn producers about this ever-so-often risky proposition of planting soybean seed into dry soil, or using cover crops temporally right up to the Round-Up burn-down before planting.  Preventing erosion is a good thing, but transpiring off critical stored water is a definitely a BAD thing.  There is no FREE LUNCH!   

- Jim

Friday, June 8, 2012

Aster Yellows Was Confirmed in Oat

As a followup to last weeks article entitled Oat and Necrotic Leaf Tips and Margins Dr Russ Groves Lab PCR confirmed the presence of aster yellows in oat. We have also submitted wheat samples showing similar symptomology to Dr. Groves for analysis. Those should be done early next week. There are no known feeding issues related to this pathogen so heavily infected oat can be fed as a forage though tonnage and quality will likely be diminished.