Corn Newsletter : 2018-34

  1. Seed Quality Issues in Soybean

    Author(s): Anne Dorrance

    Let’s face it – we’ve had historic rains in parts of Ohio during 2018 and we are now observing many late season issues that come with this.  Seed quality is one of them and the symptoms or warning signs that there could be issues are on the stems.  The stems in some fields are heavily colonized with a mix of disease pathogens that cause Anthracnose, Cercospora, and pod and stem blight (Figure 1).  The bottom line is that all of these diseases can be better managed with higher levels of resistance but ultimately during 2018 – we had a perfect storm, lower levels of resistance combined with higher than normal rainfall conditions and add in the presence of a new insect pest, stink bugs.  Below I’ve outlined the general conditions of the crop and for each disease, the distinguishing characteristics.

    1. Discolored, moldy seeds along with shriveled seeds are very evident in some fields (Figure 2).  Some reports indicate that it is worse around the edges but not in all cases.  Sometimes the pods look fine until they are cracked open and others the outside of the pod is a definite give away.

    2. Fungi in the genus Cercospora can cause two different diseases, frogeye leaf spot which also affects and stems and seed is caused by Cercospora sojina; and purple seed stain is caused by a complex of species, the most common has been C. kikuchii, The symptoms of frogeye leaf spot during the season were well documented this year, but on stems and pods they are not well described.  In our experience, the gray to black smudges on seed and yield the conidia of this pathogen.  For C. kikuchii, the first symptoms can appear on the petioles during the reproductive phases.  These appear as purplish to reddish streaks which turn darker after leaflets drop but the petioles can remain on the stems.  On seed, dark reddish purple blotches will appear. 

    3. Diaporthe pod and stem blight including Phomopsis were very apparent this year.  Some of the stems I collected this season were just pure fruiting structures.  This is a complex disease, in that there are several closely related fungi that can infect soybeans throughout the growing season.  These sometimes appear as black dots in a row on the stem, but some species are more randomly placed over the surface of the stem or pods (Figure 3).  They are flask like structures that hold the overwintering spores. We have documented several different species causing substantial losses in Ohio over the past 3 years.

    4. Anthracnose – this has been very rare in Ohio but this year I did find it on petioles early on some susceptible varieties.  This is another one that looks like a black dot, but this fungus, Colletotrichum truncatum and related fungi have hairs (setae) that are around the fruiting structures.  A moist chamber and a microscope can help sort out the differences.  Pods can have lesions that are large brown and irregularly shaped.

    5. Opportunists – based on some plating we have done over the past week, there are many secondary fungi that have been able to colonize these seeds.  It will take us a few weeks to identify everything to verify that are opportunists and not pathogens, but let’s just say it is pretty ugly even for a mycologist.

    All of these fungi can affect seed health.  Fields that have a high incidence should not be used for seed, but should be fine for feed but best in low quantity.  To my knowledge there are no animal toxins associated with these fungi like we see for head scab.  For fields with low incidence, many seeds will be asymptomatic so when a fall germination test is done, the percentage of moldy seed maybe high.  Some of the seed may have some mycelium on the outside layers but have not reached the young soybean.  Over the winter, under dry conditions, the mycelium (fungus) on these outside seed tissues will die and then those seed will appear normal in a germination test.  The point here is to keep the seed dry to prevent any further colonization of the seed.

    These fungi ALL overwinter on crop residue which then serve as inoculum for the 2019 soybean crop.  This is especially important for the no-till continuous soybean fields.  There are a few management strategies that can be done for 2019.

    a) Don’t plant the same variety back in the same field – Rotate varieties and look for those with better resistance scores than your current one.

    b) Do something to help break down the residue, it doesn’t need to be a lot, but some light tillage to bury some of the residue will go a long way.

    c) Rotate to wheat, barley, or corn.  These are non-hosts for this group of pathogens and planting something else in that field will go a long way to reducing inoculum for when soybeans are put back in that field.

     

  2. Syngenta Corn Seed Settlement Claims Due Oct.12th

    Author(s): Peggy Hall

    Those post cards advising producers of a $1.51 billion settlement in the Syngenta corn seed lawsuits are legitimate, and corn producers seeking compensation from the settlement must file claims by 11:59 p.m. on October 12, 2018.  The settlement is the result of class action and individual lawsuits alleging that Syngenta failed to receive import approval from China before selling its genetically modified Viptera and Duracade seeds in the United States, which led to the rejection of U.S. corn shipments and a lowering of corn prices from 2013 to 2018.

    Who can file a claim?

    Three types of claimants that were involved in the U.S. corn market between September 15, 2013 and April 10, 2018 may file claims: 

    • Corn producers, which includes any owner, operator, landlord or tenant who shared in the risk of producing any variety of corn, not just Syngenta varieties.  Landlords who operated under fixed cash leases are not eligible.
    • Grain handling facilities that purchased, transported, stored, handled and sold any variety of corn. 
    • Ethanol production facilities that produced, purchased and sold dried distillers' grains from any variety of corn.

    How to file a claim?

    File electronically through a secure, encrypted portal at www.CornSeedSettlement.com or download a printed form on the same website to file via U.S. mail.  Claimants must file using either a federal tax ID number or social security number and must file a separate claim for each Form 578 filed with FSA.  Note that the settlement claims administrator states that all claims information is confidential and will be destroyed after the payment of claims.

    How much will a claimant receive?

    Payments will vary and will depend upon the total number of filed claims.  For corn producers, the claims administrator will determine payments based on the following factors: (1) compensable recovery quantity as calculated by number of acres, ownership interest, NASS county yields and predetermined marketing year averages, (2) the year of planting, (3) the producer’s ownership interest, and (4) whether the producer purchased and planted Agrisure Viptera or Duracade seed or a different variety.

    When will claimants receive payments?

    A claimant might not receive a payment for about a year.  A court hearing to approve the settlement will take place in the U.S District Court in Kansas on November 15, 2018.  If the court approves the settlement, those who object to the approval can file appeals.  Final payments won't occur until the court resolves all appeals, which could take about a year or more.

    Must claimants report payments as income?

    Class action settlement payments that compensate for the loss of business income should be reported for tax purposes.  Claimants should consult with tax advisors to determine IRS reporting requirements.

    For more information, an extensive list of frequently asked questions about the Syngenta corn seed settlement is available here

     

  3. Aphids and Barley Yellow Dwarf

    With the recent warm temperatures, we have been receiving a few questions on the risk of aphids in wheat and the transmission of barley yellow dwarf virus (BYDV). How should growers prepare and gauge the risk of both aphid infestation and BYDV transmission?

    First, aphid infestations that cause economic damage are rare in Ohio either in the autumn or spring. There are several species of aphids that infest wheat, and most cannot overwinter in Ohio (they migrate from the southern US). However, aphids can, under certain conditions, build in numbers and damage wheat by feeding on the plant during seedling stages. A suggested treatment threshold for aphid management in wheat is 50 aphids per linear foot of row. Given the warm temperatures, we recommend that growers scout wheat fields to see if any aphids are present.

    Second, since economic feeding damage is rare, the larger concern is BYDV transmission. For aphids to successfully transmit the virus, they normally need between 12 and 30 hours of feeding to acquire the virus, and then 4 or more hours of feeding to transmit it. However, aphids are capable of acquiring the virus after feeding on infected plants for only 30 minutes and, once they acquire the virus, they can transmit it to healthy plants for the rest of their life. The typical symptoms of this disease are erect leaves with yellowish to reddish-purple tips. Yield reduction due to BYDV is generally greater when infections occur in the fall than in the spring. BYDV tends to be most severe in fields planted before the fly-free date in which aphid populations can reach high levels. However, some fields planted after the fly-free date may still have high levels of BYDV, most likely because of warm temperatures that kept aphids active for a longer time period.  Recommended management tactic for BYDV are as follows: 1) plant varieties less susceptible to BYDV; 2) delay planting until after the Hessian fly safe date to avoid early fall infections; 3) balanced fertility; and 4) controlling volunteer wheat, barley, and oats.

    Spraying insecticide to control aphids in an attempt to manage BYDV is open to discussion, and not a recommended tactic. The main reason is that only a few aphids are needed for successful BYDV transmission. Any aphids present prior to spraying may have already transmitted BYDV, while other aphids may continue to arrive in the field after spraying. When spraying insecticides to control aphids early, growers should know that the residual effect of the insecticide may not last long enough to protect against later aphid population buildup nor virus transmission. Though insecticides applied after infection will reduce the aphid population, it will not prevent the disease from developing once the plants have been infected. Keep in mind that insecticidal seed treatments might prevent establishment of early arriving aphid populations, but they have to feed to get a toxic dose. In feeding, the aphid may transmit BYDV and, once infections occur, there is very little that can be done.

    There are situations where it is acceptable to spray for aphids, and where insecticide application might pay. These include: 1) wheat under drought stress with aphids present; 2) growing a variety known to be susceptible to BYD with aphids present; 3) wheat being grown for seed; 4) wheat that is highly intensively managed with a 100+ bu/A potential yield; and 5) wheat planted before the fly-free date. However, for most growers, cost-effective control of BYDV may not be possible by aphid spraying.

    Note: We apologize for incorrectly referring to soybean aphids in an earlier version of this article.

  4. A Few Things to Consider in Planting Wheat after Corn

    Author(s): Pierce Paul

    Some Ohio wheat growers are thinking about planting wheat after corn to avoid some of the late planting issues we have had to deal with over the past few years. Indeed, timely planting will result in good stand establishment (more tillers per foot of row) and reduce the risk of winter kill. However, planting wheat after corn to ensure that the crop is planted early enough has disadvantages.

    In wheat following corn, being both members of the grass family, both crops may be affected by some of the same pests and diseases. One such disease, and by far the one of greatest concern, is head scab, caused by Fusarium graminearum. This same fungus causes Gibberella ear and stalk rot in corn. Consequently, wheat planted into corn stubble is more likely to have head scab and vomitoxin problem next year, especially if late-spring, early-summer conditions are wet and humid. Our studies have shown that when host crop (corn, wheat or barley) residue is abundant (more spores of the fungus present), only a few days of wet and humid conditions during flowering are needed for head scab to develop and vomitoxin to exceed critical grain marketing thresholds (2 ppm). With the high levels of Gibberella ear rot we are seeing in some fields this year, there will be lots of spores around next spring, increasing the risk of head scab if conditions become wet and humid during flowering. This is exactly what happened in 2009-2010 – Gibberella ear rot in corn in 2009, followed by high levels of head scab, vomitoxin and grain rejection in wheat in 2010. Remember, one of the best ways of minimizing the risk of head scab and vomitoxin is to plant wheat after soybeans and not after corn. LET US BREAK THE CYCLE OF VOMITOXIN PROBLEMS!!

    If you HAVE to plant wheat after corn or have already done so, hopefully you have planted a scab resistant variety or will do. Even when wheat is planted after soybean, planting a scab resistant variety is highly recommended. In addition, plow under the corn stubble before planting wheat and be prepared to apply a fungicide next year at flowering if the weather becomes favorable. These approaches will minimize, but not eliminate the risk of scab in wheat planted after corn.

About the C.O.R.N. Newsletter

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.

Contributors

Amanda Bennett (Miami County)
Andy Michel (State Specialist, Entomology)
Anne Dorrance (State Specialist, Soybean Diseases)
Chris Zoller (Tuscarawas County)
Debbie Brown, CCA (Shelby County)
Elizabeth Hawkins (Field Specialist, Agronomic Systems)
Eric Richer, CCA (Fulton County)
Garth Ruff (Henry County)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Greg LaBarge, CPAg/CCA (Field Specialist, Agronomic Systems)
Harold Watters, CPAg/CCA (Field Specialist, Agronomic Systems)
Jason Hartschuh, CCA (Crawford County)
Jeff Stachler (Auglaize County)
John Schoenhals, CCA (Williams County)
Lee Beers, CCA (Trumbull County )
Les Ober, CCA (Geauga County)
Mark Badertscher (Hardin County)
Peggy Hall (Field Specialist, Agricultural & Resource Law)
Pierce Paul (State Specialist, Corn and Wheat Diseases)
Rory Lewandowski, CCA (Wayne County)
Sam Custer (Darke County)
Sarah Noggle (Paulding County)
Wayne Dellinger (Union County)

Disclaimer

The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.