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Soybean Insects

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New Multi-State Extension Publication: Managing Insecticide-Resistant Soybean Aphids

The first pyrethroid resistant soybean aphids were reported in Minnesota in 2015. Since then, pyrethroid resistant soybean aphids have been reported in Iowa, North Dakota, and South Dakota. In an effort to address resistance, researchers from those states have put together a new extension publication.

Brown roots with white spots on them. The white spots are SCN cysts that contain eggs. Smaller image shows a broken cyst with eggs coming out of it.

Test Your Soil for the Soybean Cyst Nematode (SCN) This Spring

The soybean cyst nematode (SCN) is a major soybean pathogen that causes significant yield loss. Fields that were not tested for SCN last year can still be sampled this spring to determine the presence of SCN or SCN population changes if testing was done in the past.

Green soybean plant with epidermis peeled back revealing numerous orange larvae

Soybean Gall Midge: What We Know So Far

In 2018, South Dakota soybean farmers were faced with a new soybean insect pest. What started with dying field borders ultimately ended with yield losses throughout many fields on the Eastern side of the state. We determined that the pest in question was the soybean gall midge.

Green soybean plant with holes on the leaves (indicated by red arrows) caused by bean leaf beetle feeding.

Scout Soybeans for Bean Leaf Beetle Feeding

We are receiving numerous reports and also observing very large bean leaf beetle populations this year. As a result, there is also a lot of concern about soybean defoliation due to the emergence and subsequent feeding by the overwintering adult population.

Yellow and black beetle on green soybean leaf.

Watch for Bean Leaf Beetles

Some soybean in South Dakota has emerged and it is already being attacked by early-season bean leaf beetles. So far, observations of adult bean leaf beetles emerging from fields and defoliation of soybean have been in Southeastern South Dakota.

Small fly with black and white alternating bands on legs.

Soybean Gall Midge: It’s a New Species!

Researchers recently determined that the soybean gall midge, discovered in South Dakota in 2015, is actually a previously undocumented species. The origin of the new species, Resseliella maxima Gagné, is still unknown.

A yellow beetle with a black head, and square black markings on its back standing on a soybean leaf.

2019 South Dakota Overwintering Bean Leaf Beetle Predicted Mortality

Overwintering bean leaf beetle adults will soon start emerging as they do each spring. This overwintering generation is capable of causing serious defoliation injury to seedling soybean plants.

Green soybean with wilting/dying soybean within the same row.

Soybean Gall Midge Larvae Found in South Dakota

Although we have yet to capture any adult soybean gall midges, the reports and observations of soybean gall midge larvae in soybean are pouring in this week. In Clay and Union counties, infested soybeans are now showing signs, with plants beginning to wilt and die in some cases.

Three common soybean defoliating pests. From left: Green cloverworm, grasshopper nymphs, and thistle caterpillar.

Monitor Soybean for Defoliating Insects

While scouting soybean this week I noticed quite a few defoliating insects that were present in the field. So far, the feeding injury is minimal, but it is a reminder that we need to be diligent in monitoring leaves for defoliation and fields for these insect pests.

Base of soybean stem with orange larvae present under the epidermis.

How to Scout For Soybean Gall Midge

Soybean gall midge have been reported in three counties in South Dakota in the past week: Clay, Union and Lincoln. Scouting for soybean gall midge can be as simple as finding wilting or dying plants along the edge of the field, or it can be rather difficult if the plants are currently asymptomatic.