Fall Insect Watch – Ohio Ag Net

By Dusty Sonnenberg, CCA, Ohio Field Leader, a project of the Ohio Soybean Council and the soybean check-off

It took another year to pay attention to insects in field crops.

“After a bit of a dry start to the season and stressed soybeans, we were lucky not to see a lot of early insect pressure,” said Andy Michel, professor of entomology at Ohio State University. and insect culture specialist for OSU Extension. “It wasn’t until mid-July that we started seeing the insects moving around the soybean fields. Historically, June and July are when soybean aphids would be expected. In recent years, it’s become more of a season-ending past. Now July is when we start looking for bedbugs.”

Stink bugs cause damage by feeding on pods and developing beans.

“Stinkbugs have become a major soybean pest in Ohio,” Michel said. “Stinkbugs enter fields in mid-July when soybeans are in the reproductive flowering stage, and they time egg hatch during the reproductive stage to feed on developing pods. It’s this early feeding that can do the real damage.

In collaboration with Kelley Tilmon, Field Crop Insect Specialist for OSU Extension, and with funding from the Ohio Soybean Council and levy, a monitoring program was established and several stink bug resources were developed and distributed to producers.

“There are 3 to 4 species of chinch bugs that are commonly found in Ohio fields. Treatment thresholds are based on the number of bedbugs found,” Michel said.

The overwintering abilities of bedbugs vary by type.

“We’re all familiar with the brown marmorated stink bug, which tries to get into our homes in the fall and winter. These will overwinter in protected areas in Ohio,” Michel said. “Some of the other types, like the green stink bug and the brown stink bug, will overwinter in the south and then migrate north in late spring and summer. By monitoring their movement, we get an idea of ​​the pressure that will be exerted each year. »

It should be noted that there are also bedbugs that are considered beneficial insects that feed on other pests. Defoliators are another major insect problem for soybeans.

“In the past we’ve seen a lot of bean leaf beetle defoliation, but more recently and especially this year we’re seeing more defoliation from grasshopper feeding,” Michel said. “These are usually insects that feed on the edge of the field. The good news is that a soybean plant can withstand a fair amount of feeding damage and still be able to catch sunlight with the leaves lower in the canopy. The amount of sun the soybean plant is able to capture is more critical than the level of defoliation of the upper canopy leaves.

New tools are available to help farmers assess their fields.

“Last year, with funding from the USDA and the Soybean Council, we developed soybean defoliation tools that are 3D printed,” Michel said. “Farmers often overestimate the level of defoliation in a field. This tool is a series of 3D leaves with varying levels of defoliation that a farmer can use to compare to the top leaves in their field. We recommend taking a trifoliate (three leaf) soybean and discarding the most feeding and least feeding, then assessing the average feeding level in the field.

Defoliation is also assessed based on crop growth stage.

“There are different defoliation thresholds depending on the growth stage of soybeans,” Michel said. “From V1-R2 you can go up to 30% defoliation without needing treatment. From R1 to R5 is the most critical development stage for the crop and we are lowering the threshold to 10% defoliation. This is because we are trying to catch the sunlight and put the energy into the bean.Above the R6 growth stage, the threshold is 15% defoliation.These estimates are based on an average over l whole factory and field.