Is There Any Lemonade to Make out of These Lemons?

We are past the middle of May and I’m getting calls for data already on the seed treatment trials that we have scheduled for the 2019 season.  But in all honesty, I’m glad they weren’t in the ground! Based on the rainfall levels around the state, it would have been a flooding injury test not a water mold fungicide efficacy test.  Additionally, knowing the vulnerability of our 2019 seed crop, I’m actually relieved that our soybean test plots were not in the ground.  Soybean seed rot and seedling damping-off is caused by a number of pathogens of two groups:  true fungi (Fusarium spp. and Rhizoctonia) and watermolds (Pythium and Phytophthora spp.).  The seed treatment packages now available for farmers have products that cover this very diverse spectrum of soil borne pathogens but not flooding.  If the fields were flooded, after planting, the damage to the seedlings will have a different color as well as a different smell.  Flooding injury kills everything in the soil, and has a very distinct smell and the roots of the plants, the outside cortical tissue of the root can be easily stripped off of the seedling so that it looks like a rat tail.  Damage from pathogens, will appear as tan to dark brown in color and the tissue is soft- leaving no roots left all.

To test or bait for water molds in the greenhouse we need to treat the soil in a very specific matter to enhance disease.  To bait and isolate from soybean seedlings we first flood the soil, let it drain, typical of a 3 to 4” rain in most of Ohio soils.  We then incubate the soil wet for 1 to 2 weeks, let it dry a bit, plant it, flood it again and for most of our samples lots of seedlings with damping-off develop caused by water molds. So our soils are primed, the oospores in these soils have probably broken dormancy and are ready for the right conditions.  To maximize the yield potential still available this season on soybean, plant those fields on your farm that are prone to saturation in the best planting conditions possible (aka not in front of a big storm).

The seed treatments that are on the seed, will not damage the seed IF, the seed is stored cool and dry.  I typically store seed with seed treatments for 1 to 2 years in cool, dry conditions for my students to evaluate in greenhouse or laboratory tests.  So as we wait for any planting conditions, take care of that seed.

For those fields that will be switching from corn to soybean – let’s think about this.  We are quickly moving to continuous soybean on 50% Ohio Soybean acres.  This is not an ideal situation as it leads to the rapid build-up of soybean cyst nematode, residue pathogens of frogeye leaf spot and soil borne root rot pathogens.  So as your making this decision, look at the history and sit down with your variety listing.  If you had frogeye leaf spot last summer in a field (https://u.osu.edu/osusoybeandisease/foliar-diseases/frogeye-leaf-spot/), this would not be ideal to move to continuous soybean – I do this on the research farm to improve the possibility of getting disease.  If you must, then only plant a variety with high levels of resistance to frogeye leaf spot.  If you are moving into 5 years or more of soybeans, my big question is when did you last pull soil for a SCN test?  We are picking up quite a few fields (>50%) in Ohio with populations of SCN that are adapting to the primary source of resistance that companies have incorporated into their germplasm (PI 88788, R3).  Continuously planting this one type of resistance will push the adaptation much faster to this source of resistance. There is more information on SCN at https://u.osu.edu/ohscn/ and from the SCN Coalition site: https://www.thescncoalition.com/.  

 

 

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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.