Dry weather and resistance made for good conditions for soybean cyst nematodes in 2021, and Greg Tylka said the time is now for producers to take action.
In this year’s Iowa State University SCN yield tests, seeds with Peking resistance once again performed well compared to the more commonly found PI-88788 resistance. SCN has shown resistance to the PI-88788 gene in recent years, said Tylka, a plant pathologist at Iowa State.
“We’ve used nothing but (PI-88788) for almost 25 years, and the pest has become resistant to it,” Tylka said. “In those days, 25 years ago, Peking had lower yields than the 88788, so that’s why companies bred with it.”
Peking has been a fractional part of the market share. Despite the higher performance in the Peking varieties these days, he said it makes up less than 5% of the options available to many Midwest farmers.
Meanwhile, SCN populations continued to rise and drag on yield, making it time for a shift, Tylka said.
“We are going to continue to lose ground in the battle against SCN,” Tylka said. “It’s frustrating to see this play out in slow motion, but it’s inevitable.”
Tylka encouraged farmers to talk to their seed dealers about seeing more Peking products in their seed options in order to limit the resistances already showing. Other management practices, such as seed treatments, are available, but are often less consistent at battling the pest.
“Let your voices be heard,” Tylka said. “Our data is consistent over the years that Peking performance just gets better every year compared to PI-88788.”
The dry weather seen in parts of the Midwest throughout the growing season played a large part in this year’s SCN boom, Tylka said. It made for ideal conditions for SCN, dragging on yield in their test plots.
“It’s one of two things you can rely on with SCN,” Tylka said. “They thrive in dry soil. We don’t know why that is yet, but the other part of it is they prefer higher pH soils. They are both universally true.”
With the potential of a soil moisture deficit going into the 2022 growing season, that could be a recipe for additional SCN activity in soybean fields. If possible, Tylka said this may be cause to reexamine the crop plan for the upcoming season.
“Beans on beans is a bad thing to consider if you had medium or high SCN last year,” Tylka said. “Some people may not have sampled in many years, so getting that done in early spring will allow them to get a handle on any SCN problems.”