Early Harvest Reports – Soybean Seed Quality is Not Good

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David Holshouser, Soybean Agronomist & Hillary Mehl, Plant Pathologist

We appreciated the rainfall this year.  It should lead to some very good yields in many parts of Virginia.  However, the same weather conditions for high yields has led to some of the worst seed quality that we’ve ever experienced.  This is in addition to the pod splitting and seed sprouting that we began observing last month.

We began seeing extremely poor seed quality in our May-planter maturity group (MG) 3 soybean in our Orange variety test last week.  The early MG 4 soybean did not look much better, but they were not yet mature.

The photo on the left is the worst that has been called to my attention.  These are April–planted early MG 3 soybean from Madison County.  To use the farmer’s words, “A real kick in the stomach.”  Soybean in this shape are pretty much a total loss.  It is especially hard when the yield potential was outstanding.

Below are photos from Westmoreland and Dinwiddie counties showing similar results.  We are not seeing the same problems in our May-planted MG 4 soybean in Suffolk, but are seeing quite a bit of purple seed stain in some varieties.

So, what caused this?  From these photos, we are seeing signs of several diseases, including Phomosis/Diaporthe, Cercospora, and anthracnose just to name a few.  However, we have not yet confirmed the diseases – samples are on the way to the Tidewater AREC’s disease lab.

But that is just the possible diseases.  What caused the disease to be so bad?

I think that we can blame it largely on excessive rainfall (and many rainfall events) and a very warm September.  Most of the seed diseases come on strong during maturation; hence, our early MG soybean, especially those planted in April and early-May experienced those conditions.

Below is a weather summary from the month of September in Orange County, showing 2018 and long term average temperatures and accumulated precipitation.  Notice the high rainfall, especially during the latter part of the Month, when our MG 3 and early-4 soybean were maturing.  Secondly, notice the temperatures during that same time period.  This set up nearly perfect conditions for many seed diseases to form.

  

What can we do about it?  Unfortunately, we cannot control the weather.  And what we have done this year cannot be undone.  But, here are a few pointers for that may help this and in future years.

  • Harvest as soon as possible after soybean are mature. The diseases will only continue to grow and develop.  If you have drying capability, harvest at a little higher moisture and dry it down to 13%.
  • Plant varieties best adapted to your farm(s). While you have discovered (and heard me – David – say) that early-planted early-maturing varieties have very good yield potential if we have a cool and wet July and early-August (not the normal), there is always the risk of poor seed quality.  Only if September is cooler than average and rainfall is not excessive will this system give us good quality seed.  Year in and year out, May-planted late-MG 4 and MG 5 soybean are our best overall choice.  Also, it is rare that double-crop soybean have poor seed quality.
  • Select disease resistant varieties. Most companies do not list resistance to many of our seed diseases, but we have seen differences in varieties.  Look over our final soybean variety test results for more information on seed quality scores and purple seed stain ratings.
  • Select disease-free varieties. Next year, notice your seed quality.  While most companies will not bag disease-ridden seed, some could sneak through.  Seed treatments may be in order.
  • Minimize insect damage to pods. Though not necessary for infection, insect damaged pods are more likely to be colonized by fungal pathogens.
  • What about foliar fungicides? We have not found that foliar fungicides can overcome warm and wet conditions during seed maturation, especially when applied to the R3 stage.  Will a later application help?  That is hard to say. In some cases, applying a fungicide at R5 will improve seed quality, but this is not a sure thing and a yield is unlikely to be improved with later applications.

Fall armyworm outbreak in southwest Virginia – and management recommendations

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Prepared By: Tom Kuhar, Adam Formella (Entomology graduate student), and Sally Taylor (TAREC)

Fall armyworm larva.

Over the past two weeks fall armyworm outbreaks have occurred in southwest Virginia with reports from Abingdon to Roanoke, VA in turfgrass and small grain crops. Some new plantings of rye have been completely destroyed and densities of armyworms have exceeded 10 per square foot in some areas.

Fall armyworm (Spodoptera frugiperda) is a tropical moth native to warm climate areas of the western hemisphere. It cannot successfully overwinter in Virginia. However, this armyworm moth (see Fig. 9) is a strong flier, and populations can migrate throughout the eastern United States in the late summer and fall months, sometimes in very high populations like what recently occurred in southwest Virginia. Phil Blevins (VCE ANR Agent in Washington Co.) was monitoring a fall armyworm bucket trap for us in sweet corn in Abingdon, VA, and 2-3 weeks ago detected a huge jump in moth catch.  This was a harbinger of things to come.  Female FAW moths can lay up to 10 egg masses (each with 100 – 200 eggs) (see Figs 1-2). So, it’s no surprise how quickly the densities of armyworms can build up from just a few egg laying moths in a field.
Fall armyworm can feed on a number of different host plants, but prefers grasses, small grains, corn, and sorghum.  Turfgrass has been particularly hit hard by this pest this week around the New River Valley.  In turf, FAW larvae can consume all above-ground plant matter causing noticeable damage and bare spots.  This can happen quickly.

Control
Insecticides recommended for control include most pyrethroids (such as bifenthrin, lambda-cyhalothrin, Mustang Max, Baythroid XL, etc..), Lannate LV, and many of the more selective (lepidopteran-targeting) insecticides such as the diamide Prevathon, Coragen, Acelepryn, Besiege), indoxacarb products like Steward, Avaunt eVo, Provaunt, spinosad (Blackhawk, Tracer, Matchpoint), Radiant, Intrepid Edge, as well others. Consult the relevant Pest management Guide for specific recommendations on the various commodities. Please note that control of large larvae is sometimes difficult with any insecticide. Link to the VCE Pest Management Guides for Field Crops, Vegetables, and Turf are provided below.

Links to Pest Management Guides
Turf:
http://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/456/456-017/turf.pdf
Field Crops:
https://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/456/456-016/insects.pdf
Vegetables:
https://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/AREC/AREC-66/AREC-234.pdf
https://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/456/456-420/456-420.pdf

Sources
http://entnemdept.ufl.edu/creatures/field/fall_armyworm.htm
Luginbill P. 1928. The fall armyworm. USDA Tech. Bull. No. 34.

 

Some late season activity by corn earworm and fall armyworm in parts of Virginia

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Although most of our sweet corn has been harvested for 2018, there are still some late-planted fields that may still be at risk to insect attack.  While most of the remaining pheromone traps around the state had low catch numbers, Mark Sutphin VCE Frederick County saw a great jump in corn earworm catch this week at one of the farms still growing sweet corn.  Keep in mind that corn earworm is also a pest of many other crops that may still be at risk this fall including tomatoes and beans (See images below).

Please keep in mind, In an effort to fend off any more pyrethroid insecticide resistance development in our corn earworm populations, rotating to another insecticide than a Class 3 (pyrethroid) is highly encouraged for at least one spray. Diamide insecticides such as Coragen or Besiege, the carbamate Lannate LV, or the spinosyn Blackhawk, are all effective non-pyrethroid options.

Also, Phil Blevins VCE Washington County reported some of the highest fall armyworm catch of the year >200 moths in the bucket trap this week.  These moths showed up late to southwest Virginia and are probably not going to be much of a pest concern in the state, and they will not successfully overwinter here as they are a tropical moth.

Fig. 1. Corn earworm damage to snap bean pods.

Fig. 2. Corn earworm (=tomato fruitworm) damage to tomato fruit.

 

 

Soybean Sprouting in the Pods/Pod Splitting

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We are seeing immature soybean once again sprouting in the pods in Suffolk and Gloucester County, and I heard of this happening in other states.  This seems to occur every 3-6 years somewhere.  Although I don’t have a great explanation for why this occurs, it usually happens when there are good growing conditions early followed by 2-4 weeks of drought stress during pod formation, and then excellent conditions return for seed fill.  Typically, it happens in big-canopied soybean (lots of leaf area) with lots of yield potential, but not enough pods (or big enough pods) to fulfill that potential.  I think that the seeds enlarge so much that the pod splits.

Keep in mind that I’m talking about immature seeds and pods.  This can also occur after the crop matures (R7 to R8) when we get excessive rainfall after the seed in question has dried down.  But, I have not seen that yet this year.

There is little that you can do about it.  Those sprouted seed will usually dry up on the plant and be blown out the back of the combine.

Although there has to be some yield loss, I’ve not seen it to be very great.  And, I suspect that if you did not notice the sprouted seed, you probably would not know that you had a loss.

For more information, see previous blogs on this subject.

Wet Conditions May Lead to Soybean Seed Sprouting

The Good and Bad of a Wet September

Calibrate your yield monitor – a checklist

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While this post is likely too late for corn, it does apply to other crops.  If you have yet harvested all of your corn, it’s never too late to calibrate your yield monitor.

First, I am no expert in calibrating yield monitors.  My experience with the process only involves showing up to the farm with an accurate weigh wagon (or we use their grain cart), riding with the combine operator as he harvests a known area of the field, weighing the load and obtaining a moisture from the load (with a calibrated moisture tester), then watch him do the calibration.

Still, I understand the need for calibration although it takes time and may mean looking in the manual to learn or refresh one’s memory on the process.

John Barker, Knox County Extension Educator (Ohio State Extension) wrote an excellent article, “It’s almost that time of year … Don’t forget to calibrate your yield monitor!”, which is a step-by-step checklist of how to do this.  I highly encourage all to read it.

We do have several weigh wagons located around the state that Virginia Cooperative Extension uses for our on-farm research.  If you want me or one of your County Agents to help with this process, let us know.

Peanut harvest is coming sooner than we thought this year!

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Friday, Sep 7th, a pod-blasting clinic was organized in Windsor, Isle of Wight County in Virginia. Farmers brought samples for maturity evaluation from 40 fields, in majority from the IOW but a few were from Suffolk and Southampton. Samples were taken from fields totaling a minimum of 3100 acres of peanut. Based on the mesocarp color, we identified that one sample was ready to dig, 12 in a week, 15 in a week and a half (10 days), 8 in two weeks, and 4 in three weeks or more. This indicated that two thirds of these fields were ready for digging after this week and after the hurricane Florence has passed.

Peanut varieties planted were in majority Bailey and Sullivan with only very few acres of Wynne and Emery, the last being a new cultivar just released in 2015. On these checked fields, farmers did not irrigate and only one farmer used Apogee, a growth regulator that could have affected maturity. Defoliation due to leaf spot was almost absent in all fields, as it was rootworm damage.

The earliest to be dug, in no more than a week, were fields planted during the first week of May and receiving constant rainfall in June, July, and August. Note that precipitation received in July and August exceeded by far this year the multi-annual average for most fields. Some fields planted in mid-May and constantly rained out, also showed digging approaching in 7-10 days (picture below). The only early May plantings a little behind, 10-14 days from digging, were fields with a dry June, regardless if for the rest of the summer they were wet; and the majority of fields planted in mid-May. Based on the color charts, the fields planted during the last week of May could wait three weeks or more before digging. Meanwhile, several other pod-blasting clinics will be organized to help farmers decide when and what fields to start digging with.

This result came to no surprise. It has been determined that Bailey requires about 2700 °F heat units (or GDD) to reach optimum maturity. The Cotton – Peanut Infonet online service provided by Virginia Tech here https://webipm.ento.vt.edu/cgi-bin/infonet1.cgi shows that by Sep 7th peanut planted on May 1st received 2649 °F in Suffolk, 2637 °F at Capron in Southampton, 2718 °F at Skippers in Greensville, and 2640 °F at Waverly in Sussex. Researchers at the University of Georgia determined that every event of rainfall and irrigation received by a crop at one inch or above has an effect equivalent with 10 °F heat units and can speed up peanut maturity. If so, 100 or 200 heat units are to be added to those measured by the thermometer.  Indeed, under the conditions of this year early May planted peanuts are expected to be ready for digging 7 to 10 days sooner than last year.

Sweet Corn IPM Moth Trapping in Virginia – Week Ending September 7, 2018

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This will be final trap catch alert of the year for the sweet corn IPM program as most corn has been harvested. I want to thank all of the VCE Extension folks who monitored traps on farms in their respective counties this year: Phil Blevins (Washington Co.); Chris Brown (Franklin Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Eastern Shore AREC Entomologist, Accomack Co.); Roy Flanagan (VA Beach); Bob Jones (Charlotte Co.); Kenner Love (Page and Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk (Westmoreland Co.); Beth Sastre-Flores (Loudoun Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.).
Click on the table below to view the trap catch results (moths per night) for some of the locations around Virginia for this final week. We will send out a synopsis of the season this winter. We are still seeing some high corn earworm moth activity on the Eastern Shore of Virginia, Westmoreland County on the Northern Neck, and Frederick County in the northwestern portion of our state. With the hot weather that we’ve experienced the past 2 weeks, moth activity has probably been a little higher than usual for September. Sweet corn growers are advised to keep control measures (spray intervals) as they were during August in most counties.
We still have caught very few fall armyworm moths in our traps around Virginia; however, this insect could contribute to some infestations in the ears of late corn. In an effort to fend off any more pyrethroid insecticide resistance development in our corn earworm populations, rotating to another insecticide than a Class 3 (pyrethroid) is highly encouraged for at least one spray. Diamide insecticides such as Coragen or Besiege, the carbamate Lannate LV, or the spinosyn Blackhawk, are all effective non-pyrethroid options.

Corn earworm average moth catch per night at farms around Virginia for week ending September 7, 2018.

Fall armyworm larva.

Mid-Atlantic Crop Management School Registration is Open!

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Registration is open for the 2018 Mid-Atlantic Crop Management School for Certified Crop Adviser, Nutrient Management, and Pesticide Applicator Credits for Virginia, Delaware, Maryland, West Virginia, and Pennsylvania. The venue is the Princess Royale Oceanfront Hotel and Conference Center in Ocean City, MD on November 13-15, 2018. Register early so you can enroll in your preferred classes!

Registration: https://app.certain.com/profile/2876563
Schedule: https://sites.udel.edu/agronomy/cropschool/