For the last few years, fields across the Midwest have been plagued with the notorious soybean gall midge. Even with a lighter appearance of this pest this year, research at the University of Nebraska-Lincoln went on to learn more about this little orange bug.

The same can be said about the infestation rates of the Dectes stem borer. Although the impact of stem borer is less devastating to yields, more information about planting dates and chemical usage was shared at the 2024 UNL Soybean Management Field Day.

All in the fissures

The soybean gall midge will infest soybean plants in openings in the crop. Most commonly you will find the entry point of these pests in the fissures of the stem. If there is hail damage in soybean fields, soybean gall midge will have more of an opportunity to attack the plant.

However, Justin McMechan, UNL associate professor of entomology and an Extension specialist, and his team have found that farmers have a better chance of saving yields if there is an early infestation.

“If I had to choose the fate of your soybean plants that are infested, they are going to die anyway,” McMechan said. “Just get out of the way and let the plant population try and fix some of that issue out of the field with a lot of excess branching.”

In terms of chemical application strategies, McMechan has found that a long emergence makes it hard for insecticide to be effective. Early detection is essential to proper management.

Because these insects cut off the movement of water to the plant, they can deprive water from the soybeans and be detrimental to yields. To know if your field has soybean gall midge, a key indicator is if the plant is hard to pull out of the ground and, of course, the presence of the little orange bug.

If hail damage is present in the field, it is important to keep a close eye on gall midge.

SOYBEAN GALL MIDGE: The little orange bug has been prevalent in fields, and each year researchers across the Midwest are finding more information about this pest. This pest cuts the water supply from the soybean plant and can be detrimental to yields.

“Soybean gall midge is in a lot of the hail states,” McMechan said. “So, if you had hail after the R2 stage soybeans, I would be paying attention and taking a look at those beans in the next week or so for increased populations and the adjacent field.”

Cover crops could help reduce the pressure of soybean gall midge populations in soybean fields.

“It is possible that cover crops could put pressure on gall midge as it is emerging,” McMechan said. “They could be pulling down populations as they are either emerging or moving over. They do not live very long as adults — maybe three to five days at most is what Minnesota has documented. So, it is a closed window, and then the larvae are constantly coming off, sometimes in high number.”

Stay away from early maturity

With the Dectes stem borer, management strategies look a little different. Stem borer feeds in the pith area of the plant. So, a white center of the stem is a good indicator of health. With more than 50% of the field infested with stem borer, it’s important to prioritize harvest of those fields first.

Dectes stem borer is less detrimental to the plant because the soybean plant still can survive even if affected, as long as they do not reach the base of the plant, weakening the soybean until it falls over. Additionally, McMechan said that drought stress can increase the damage of stem borer.

DECTES STEM BORER: Although the soybean plant still can survive with minimal yield losses, there are ways to rid Dectes stem borer from the field. The biggest strategy to do this is avoiding early planting of early maturity soybeans.

If farmers have Dectes in their fields, it is important to think of these management decisions: