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Agronomic Crops Network

Ohio State University Extension


Fields are starting to turn a golden yellow – last chance to grab some data

The forcast is now turning more fall like and many fields in the state are turning that golden yellow color so if you haven’t checked your fields – this may be the last week to get some very important information.

  1.  Crop rotation is not used as often as we would like these days, but one disease that can really get us is frogeye leaf spot.  Where I planted a susceptible variety in the same field that we had frogeye before now has more than 15% of the leaf area affected in untreated plots.  If you are a continuous bean, no till farmer – then please check those fields to see what diseases might come back next year.  If you do have a lot of disease – you can make adjustments, careful variety selection, light tillage or changing crops for one to two years will reduce the impact of the disease in 2015.
  2.  Sclerotinia stem rot – It is very noticeable now in many areas of the state this year.  Note those fields and locations because the sclerotia will be with you for some time.  Make harvest plans – for severely infested fields – harvest them last.  
  3.   SDS/Brown stem rot.  Had a very interesting sample this week from a field.  Leaves were green with pale yellow spots and very little necrosis.  The first thought was SDS until we opened the stems, it was clearly brown stem rot.  It is always a good idea to split stems just to verify what you have.  It will make a difference when you choose a variety.
  4.  Uneven yellowing – as the field matures the whole field should turn golden yellow at the same time.  If one pocket turns yellow first, and you know it is not flooding or poor drainage, there is a very good chance it could be soybean cyst nematode.  Go dig some plants, hold them for 2 to 4 minutes and then look for the SCN females on the roots.  If you do have early maturing pockets, target those areas for SCN sampling after harvest.  It is always good to know your SCN numbers, To quote Greg Tylka from Iowa State “it is much easier to keep SCN low than to try and drive the numbers down after they have gotten to high”.
  5.  Dead brown plants, that look like they were hit with a flame thrower – nice and dry and crispy.  Phytophthora stem rot is the most likely culprit.  Again variety selection for those with high levels of field resistance will save you stand throughout the season.

Taking the time to assess stands and final crop health will go a long ways to reducing losses the next time that field is planted to soybean.  Enjoy the walk!

Crop Observation and Recommendation Network

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.