In early February, producers gathered in Moorhead and Grand Forks, N.D., to attend the Best of the Best in wheat and soybean research. Along with watching various live demonstrations, attendees heard from a panel of experts, which included University of Minnesota Extension Agronomist Seth Naeve, with U of M Extension and Michael Wunsch and Janet Knodel of North Dakota State University Extension.
Excess Nitrogen and IDC
Because of dry conditions, many producers are concerned about how excess nitrogen (N) will affect their soybeans. Naeve presented on high residual N and the management of Iron deficiency chlorosis (IDC) in soybeans.
“Excess N is another risk factor for IDC in soybeans,” he said .
He explained that excess N increases the PH of the rhizosphere and impedes the exchange of iron in the leaf tissue. Additionally, the soil won’t fix as much nitrogen, causing the PH level to rise.
Suggestions to manage IDC included: choosing IDC varieties, increasing populations and applying an iron chelate.
“Unless you have exhausted all other options,” Naeve said, “I don’t think it’s necessary to change rotations.”
Managing White Mold
Michael Wunsch addressed proper management of white mold in soybeans, stressing the importance of using the proper droplet size when applying fungicide.
“You can almost double your yield by getting the droplet size right,” he said. “As the canopy becomes more closed, we need coarser droplets.”
Wunsch also illustrated the results of spraying fungicide at various growth stages.
“Fungicides don’t translocate into new growth,” Wunsch said, “so you should spray at 100 percent R2, unless the canopy closes early.”
Every year, farmers work to keep insects from overrunning their fields. Knodel gave a field crop insect update where she highlighted multiple problem pests like the two-spotted spider mite, which was worsened by the drought.
“It attacks over 500 different plants, including all of our field crops,” she said. “They can explode quickly with a short life cycle when it’s really hot – only five days.”
Knodel doesn’t recommend a pre-mix treatment for spider mite control because there are 2 active ingredients at a lower toxicity rate.
Knodel also touched on grasshoppers, a heightened issue because of the drought, aphids, bean leaf beetles and caterpillars.
The Minnesota Soybean Research & Promotion Council is a proud sponsor of the Best of the Best.