Stalk rot is showing up in some Iowa cornfields already. "Now is the time to start checking for stalk rot in your fields and decide which fields you should schedule to harvest first," says Alison Robertson, Iowa State University Extension plant pathologist. She recommends the following procedure to assess your fields prior to harvest.
If you are scouting for stalk rot, look for discoloration on the lower part of the stalk, and check the stalk for firmness by pinching the lower internodes. Simply pinch the stalk between your thumb and fingers. Healthy stalks are firm and won't compress easily.
Check cornstalks by pinching the lower internodes
If a node can be "squished" or if it otherwise feels soft, that means stalk rot has set in and risk of lodging goes up. Instead of this "pinch test," some agronomists and farmers prefer using the "push" test, but either way works fine, notes Robertson.
Check at least 100 plants per field; 20 plants in five spots in the field. Better yet, try to test each of your hybrids, with special attention given to any that have low stalk rot and/or standability scores. Try to sample the different "management areas" you have in a field, assess them separately. Various tillage systems, crop rotations, drainage issues and fertility histories are what she means by different management areas.
Prioritize scouting towards fields that showed stress first, especially if they've had significant foliar disease this summer, advises Robertson. "If around 10% or greater of the stalks have issues, you need to do your best to get those hybrids harvested first to reduce the risk of significant lodging.
Sudden death syndrome and other soybean diseases
ISU Extension field agronomists around Iowa are getting a fair number of calls from farmers about odd things showing up in bean fields this fall, with all the wet weather. Clarke McGrath, an ISU Extension agronomist at Harlan in western Iowa, suggests you read an article that ISU Extension plant pathologist Daren Mueller wrote last year in the ISU Integrated Crop Management Newsletter.
"We are seeing nearly the exact same diseases in field areas around here in my area of Iowa," says McGrath. "No doubt the recent rains that some areas caught will create more disease issues for our bean fields, so hopefully this article by Daren Mueller will help answer your questions." The article is online at extension.iastate.edu/CropNews/2014/0829Mueller.htm.
Looking on the bright side, "the wet spring in 2015 and subsequent SDS pressure could tell us a couple of things," says McGrath. "Was there any negative yield impact from the early season 'halo effect' that we saw on some of the ILeVO treated beans this spring? This has been the subject of much debate among farmers this year. How did ILeVO hold up in the face of this much SDS infestation? There are a fair number of acres treated out there this year, with ILeVO. So we should see some good yield data on the varying levels of SDS pressure in various fields."