Thursday, September 18, 2014

Fall is Still a Good Time to Sample for SCN and Other Plant Parasitic Nematodes

The WI Soybean Marketing Board (WSMB) sponsors free nematode testing to help producers stay ahead of the most important nematode pest of soybean, the soybean cyst nematode (SCN). Eggs of SCN persist in the soil between soybean crops so a sample can be submitted any time that is convenient. The soil test report indicates the number of eggs in the sample and is useful for selecting the right variety for the next soybean crop. Retests of fields planted with SCN-resistant varieties over multiple years shows how the nematode population is responding to variety resistance and provides an early warning should the nematode population adapt to host genetics.

In the spring of 2012, the WSMB expanded the nematode testing program to include other pest nematodes in addition to SCN. These nematodes are less damaging to soybean than SCN but can cause enough yield loss to warrant treatment. As is the case for SCN, there are no rescue treatments for nematodes so the primary purpose of this year’s soil test is to plan for next year’s crop. Soil samples collected in corn for nematode analysis have predictive value for explaining yield if they are collected before the corn V6 growth stage. Sampling early in the season will provide information about the risk potential for the current corn crop AND the next soybean crop.

The assays used to recover nematode pests other than SCN in soil require that the nematodes are alive. So, it is important to keep the samples moist and at least room temperature cool. Collecting a sample that includes multiple cores ensures that there will be plenty of root pieces to assay. It is not necessary to include live plants in the sample. The soil test report will indicate which pest nematodes are present and at what quantities and their damage potential to soybean and corn based on the numbers recovered.  

Free soil sample test kits are available now and can be requested from Jillene Fisch at (freescntest@mailplus.wisc.edu) or at 608-262-1390.
For more information on SCN testing and management practices to help reduce the losses from this pest, please contact: Shawn Conley: spconley@wisc.edu; 608-262-7975 or visit www.coolbean.info.

Remember the first step in fixing a nematode problem is to know if you have one! The WSMB sponsored nematode testing program provides you that opportunity.

Monday, September 15, 2014

Harvest Considerations for Variable Soybean Maturity

Variable soil types, knolls, flooding and drought have left many growers with extreme in-field variability of soybean maturity.   There are areas in fields where the soybean seed is 13% or less moisture adjacent to areas with green seed.  The prevailing question is “When should the grower harvest?” Obviously there is no simple answer, as each field is different. However here are a set of guidelines to consider:
1.    The easiest answer is harvest the field at two different times. Take what is dry today and come back in two weeks and harvest the rest. The challenge with this approach is that today’s equipment is large and not easily moved from field to field. Furthermore many growers rent or own land over large areas where this is impractical and the whole field must be taken at once. So……
2.     The next simple answer is wait until the whole field is ready to go. As noted in our article Drought Induced Shatter, we are seeing areas across the Midwest where shattering is occurring. The general rule of thumb is 4 seeds per square foot = one bushel yield loss. At local cash prices dipping below $10.00 per bushel this is hard to see happen and not harvest. Furthermore, waiting will also lead to moisture loss in the field. As we learned the past few years, you do not get compensated for harvesting below 13% moisture. So…..
3.     If growers are concerned with shatter and/or other harvest losses the next logical approach is harvest ASAP. This opens a whole new can of worms. Harvesting ASAP will lead to a mixture of dry, wet, and immature (green) soybean seed. Be aware that if you harvest this mixture regardless of the ratio, your combine moisture sensor may not detect the correct moisture, be prepared for that initial shock when the elevator tests the grain. Next be prepared for the dockage. Most combines will leave more beans in the pod when they are wet or immature.   These beans may end up on the ground or in the grain tank as unthreshed soybeans. Harvesting seed with this variability will be very similar to handling frosted soybean seed so discounts may occur due to moisture shrink, damage (green beans are considered damage), foreign material (this is usually higher when harvesting wet beans), test weight, and heating. If you choose on farm storage to address some of the dockage concerns please refer to Soybean Drying and Storage for questions.  

4.  The last consideration I would bring forward is that the mature areas are likely going to be the low yielding pockets due to drought whereas the yet to mature areas will likely be the higher yielding areas within the field. So, in short, which yield environment would you rather focus your time and efforts to protect?  

      The question ultimately comes down to the bottom line and where you make the most $$$. If shatter is not occurring and you have good equipment that does not incur significant harvest loss, will harvesting grain that is over-dry make you more money than harvesting seed that may incur significant dockage? My guess is yes but you tell me!
Image 1. Variable Maturity (M. Rankin)

Monday, September 8, 2014

Odds My Soybean Crop Will Mature Before A Killing Frost Hits

The Wisconsin soybean crop is slowly starting to mature, however many growers and crop consultants are still concerned about the risk of frost damage to late planted fields.  In soybean an extended period (several hours) of temperatures 28 degrees F or lower is required to completely kill a soybean plant, though temperatures 32 degrees or less can still damage top growth. Those growers considering the state of their soybean crop and wondering the odds of making it to maturity before significant yield loss occurs must first correctly identify the soybean growth stage.

Once the crop growth stage has been determined we can estimate the number of days it will take for your field to reach R7 or physiological maturity.  Across our Arlington and Hancock field sites in 2014 it has taken 5-8 days to go from R3 to R4, 7-8 days to go from R4 to R5, 10-14 days from R5 to R6 and 15-20 days from R6 to R7. As a point of reference our June 20th planted soybean at both locations just hit R6 this week. Next using the three figures below that show the 10th percentile, median, and 90th percentile date when you can expect a freeze event you can estimate the risk of a frost based on your crop growth stage.

For example: If you lived in SW Marathon county there is a 10% chance that a freeze event would have occurred prior to September 11-20, a 50/50 chance that a freeze event would occur prior to September 21-30, and a 90% chance a freeze event would have occurred prior to October 1-10. So if your soybean crop just entered the R5 crop growth stage today 9/8/14 there is a greater than a 50/50 chance that crop won't make grain based on historical weather data.

Lastly if you are concerned about a freeze event please refer to Table 1 below that provides yield loss estimates of freeze damage by crop crop stage. This may help you decide whether you should risk taking the late planted soybean field as a grain crop or would that field be more valuable as a forage or green manure?


Table 1. Soybean Response to Freeze Damage
Growth Stage
Yield Reduction
R4 - Full pod
70%-80%
R5 - Beginning seed
50%-70%
R6 - Full seed
15%-30%
R7 - Beginning maturity
0%-5%
R8 - Full maturity
0%
Source: Saliba et. at. Kansas State University, 1982




Friday, August 29, 2014

Do Not Plant Saved Wheat Seed This Fall!

The race to turn the 2014 wheat crop into 2014/15 seed is on and early lab samples confirm that the percent germination from on farm sampled wheat is low. The Wisconsin Crop Improvement Association has received over 100 samples to date and over 30% have exhibited visual signs of Fusarium Head Scab (FHB) or scab. The % germ from the infected samples range from 53 to 98% (variety dependent) with an average % germ of 79%. First class certified wheat requires a minimum % germ of 85%. Furthermore invest in a wheat fungicide seed treatment this fall. Seed applied fungicides can increase % germination. On a small sample size (N = 4) the average percent germination from the addition of a seed applied fungicide increased average germination from 76 to 93%. Lastly all signs point to a late wheat establishment season. With that in mind remember to plant certified or private new seed, use a fungicide seed treatment and starting increasing your seeding rate after October 1. For more information on wheat establishment please see: Top 7 Recommendations for Winter Wheat Establishment in 2014.

Wednesday, August 6, 2014

2014 WI Soybean Yield Contest Entry Deadline is September 1

Wisconsin soybean growers have until September 1, 2014 to enter the Wisconsin Soybean Yield Contest. Two winners from each of four geographical districts in the state will receive awards (Image 1.).  "Please note the divisional lines were redrawn for 2014 based on a rolling 10 year average yield".   The first place award in each district includes a $1,000 cash prize; second-place honors include a $500 prize. Winners will be selected for having the highest soybean yield based on bushels per acre at 13% moisture. The awards ceremony is scheduled for January 29, 2015 during the Corn/Soy Expo at WI Dells.  

For more detailed information regarding the program and contest rules please visit www.coolbean.info or 2014 Wisconsin Soybean Yield Contest Rules

Entry forms can be found at 2014Wisconsin Soybean Yield Contest Entry Form.

A list of the 2013 winners and a management summary of their practices is also provided. 

For more information please contact Dr. Conley at spconley@wisc.edu. Good luck and have a safe and productive 2014 growing season!


Image 1. Geographic Division Map.


Thursday, July 17, 2014

Think Twice Before Applying Nitrogen to Poorly Nodulated Soybean Fields

Over the last 3 days my phone, email and twitter account has been blowing up with questions surrounding poorly nodulated soybeans and my thoughts regarding applying foliar nitrogen to alleviate those symptoms. I have been reluctant to write this article for two reasons. 
  1. This article will contradict some of my colleagues’ thoughts (Identifying and responding to poor nodulation in soybean) however I would agree with their scenario of applying nitrogen to early-seeded, non-nodulating soybean planted on virgin ground.
  2. I like to speak from data and I don't have a ton of data to speak from 
So with these caveats in mind here is my thought process for asking growers and crop consultants to think twice before applying nitrogen to poorly nodulated soybean fields. 
First lets start with the problem. A record number of soybean acres were planted in 2014. To get those acres both virgin ground as well as long term continuous corn acres were converted to soybean. For the most part (unless someone forgot) those acres did receive a 1x or 2x rate of inoculant. Unfortunately the perfect storm of delayed planting, poor planting conditions, compaction and poor environmental conditions all led to saturated anaerobic soil conditions that limited rhizobia infection.  These poor establishment conditions were then followed by poor early season growth conditions (cool saturated soils) delayed herbicide applications, increased herbicide rates and weed competition that further stressed the plants and limited infection. 

So with all this stress in mind why do I suggest no additional nitrogen?
  1. Once soils dry out and aerobic conditions resume the ethylene stress response in plants quickly dissipates and normal N-fixation can resume. This will lead to nodulation occurring on lateral roots as infection occurs behind the root tip of actively growing root. Furthermore once plant roots resume normal growth they will be able to take advantage of residual and mineralized soil nitrogen which will alleviate the pale green coloration.
  2. Be realistic with your yield potential. Many of the fields in question are late planted, with stunted soybeans and thin stands.  A short soybean crop will require much less N than a big one.  Salvagiotti et al; (2008) indicated in "Nitrogen uptake, fixation and response to fertilizer N in soybeans: A review" that the most likely soybean response to additional nitrogen was in high yield environments. 
  3. Be realistic with your expected yield loss in non-nodulated virgin soil environments. Somehow the idea of a 20 bu yield loss has been floating around the coffee shops. Our most recent data from a virgin soil site in 2010 showed an average +4.6 bu yield gain (range: -0.9 to 9.6 bu depending upon product) from inoculants. The untreated uninoculated check averaged 73.5 bu per acre. Also remember no history of soybean = low soil borne disease pressure and beautiful healthy roots!
  4. What are your 2014 beans marketed at $14.00 or $11.92 and dropping?
  5. What source of nitrogen are you going to apply and what is that cost per pound coupled with application cost and crop damage?
  •  Simple math equation (please insert your number for mine). 70 pounds of urea @ $0.55 per pound  + $8 application cost + $10.26 yield loss from running down soybeans (90 foot applicator = 1.9% on 45 bu $12 beans) = $56.76. At $12 soybeans you would need 4.73 bu to break even. Our average response in 2010 was 4.6 bu.
I know not everyone will agree with my thought process but understand that I am cognizant of the realities of today’s production ag world….high land rent costs coupled with high commodity prices = grower risk aversion. If you do apply nitrogen please leave at least one yield check and be fair to that yield check placement. Given our climate variability this will not be the last time we deal with this question and having data to streamline recommendations in future years makes us all better stewards and producers.

*Reviewed by Dr. Seth Naeve, Extension Soybean Agronomist, University of Minnesota.

Friday, July 11, 2014

Harvest Considerations for a Fusarium Head Blight (Scab) Infected Wheat Fields

Subsection taken from Smith and Conley 2014. Fusarium Head Blight and Other WinterWheat Diseases in Wisconsin, 2014

A survey of the Wisconsin Winter Wheat Variety Trials indicates that some fields will be at risk for dockage or outright rejection of winter wheat grain later this month. Environmental conditions that lead to high risk coupled with susceptible genetics and the grower’s inability to simply get fungicides applied all contributed to this issue.  As we move forward into harvest here are a few point to consider to help mitigate dockage and deoxynivalenol (DON or vomitoxin) risk moving forward.

1.      Scout your fields now to assess risk. Wheat near our Fond du Lac location is maturing making it very difficult to assess the incidence and severity of the infection. Understanding a fields risk will help growers either field blend or avoid highly infected areas so entire loads are not rejected.
2.      Adjust combine settings to blow out lighter seeds and chaff. Salgado et al. 2011 indicated that adjusting a combine’s fan speed between 1,375 and 1,475 rpms and shutter opening to 90 mm (3.5 inches) resulted in the lowest discounts that would have been received at the elevator due to low test weight, % damaged kernels, and level of the mycotoxin deoxynivalenol (DON; vomitoxin) present in the harvested grain.  
3.      Know your elevators inspection and dockage procedure (each elevator can have a different procedure).
4.      Scabby kernels does not necessarily mean high DON levels and vice versa.
5.      DON can be present in the straw so there is concern regarding feeding or using scab infected wheat straw.  DO NOT use straw for bedding or feed from fields with high levels of scab (Cowger and Arellano, 2013).
6.      Do not save seed from a scab-infected field. Fusarium graminearum can be transmitted via seed. Infected seeds will have decreased growth and tillering capacity as well as increased risk for winterkill.
7.      Do not store grain from fields with high levels of scab.  DON and other mycotoxins can continue to increase in stored grain.
8.      For more information on Fusarium head blight, visit this information page: http://fyi.uwex.edu/fieldcroppathology/fusarium-head-blight-scab-of-wheat/

References
Cowger, C., and Arellano, C. 2013. Fusarium graminearum infection and deoxynivalenol concentrations during development of wheat spikes. Phytopathology 103:460-471.

Salgado, J. D., Wallhead, M., Madden, L. V., and Paul, P. A. 2011. Grain harvesting strategies to minimize grain quality losses due to Fusarium head blight in wheat. Plant Dis. 95:1448-1457.