Content by Philip Rozeboom

Top: Green cloverworm caterpillar. Bottom: Cabbage looper caterpillar.

Green Caterpillars Causing Defoliation in Soybean

This week we observed several species of caterpillars in soybean fields. The most common species were the green cloverworm and the cabbage looper.

Corn and soybean fields with abundant weeds growing throughout.

Inexpensive and Simple Herbicide Programs in Corn and Soybean Will Not Be Effective

While selecting an inexpensive program with only one active ingredient in each application may be tempting due to the current agricultural economy, the result will likely be a more expensive problem in the future.

Dark green and tan curled caterpillars with an orange stripe along their sides.

True Armyworm Caterpillars Are Active in South Dakota Wheat

We have received a few reports of true armyworm caterpillars in wheat that are heavily feeding on the leaves. The big concern with these pests is that they will also clip wheat heads prior to harvest, so scouting is necessary to ensure that they don't cause yield losses.

U.S. Environmental Protection Agency offices in Washington, D.C.

Update on Chlorpyrifos Use in South Dakota

As of June 30, 2025, the labeled uses for chlorpyrifos products for food and feed are limited to alfalfa, soybean, and wheat in South Dakota. Chlorpyrifos can no longer be used to treat sunflowers.

Cream colored larvae on white and green soybean stem on brown dirt.

Dectes Stem Borer Adults Are Active in Soybean: 2025 Management Recommendations

Dectes stem borer adults have been collected from soybean in Southeastern South Dakota. The larvae of this pest are capable of reducing soybean yields by 10-15% due to tunneling activity in the main stem. Learn some tips for scouting and managing them this season.

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

Soybean Gall Midge Larvae Detected in South Dakota

Soybean gall midge larvae have been detected in soybean in southeastern South Dakota. Scouting for fields with infestations may explain wilting or dying soybean along field edges.

Green waterhemp plant next to a black, ink pen. Green soybeans in the background with brown soil in the foreground.

Waterhemp is flowering. No seeds present yet.

Waterhemp is one of the most-difficult weeds to manage in South Dakota row crops. While herbicide resistance is a great factor in the difficulty of managing this weed, the biology of the species plays an important role as well.

Left: Kochia growing abundantly in an untreated soybean field. Right: Kochia weeds burned down in a soybean field managed with an herbicide mixture.

Glufosinate + lactofen is likely an effective mixture to manage kochia postemergence in soybean

Kochia is a difficult to manage weed that infests crops across South Dakota. Mixing effective herbicides is a tactic that can reduce selection pressure on resistant weeds and increase the effectiveness of weed management.

Dectes Stem Borer in South Dakota Soybeans

Fact sheet on Dectes stem borer in South Dakota soybeans

Green plant with bright yellow flowers throughout.

Leafy Spurge: Do I spray now or wait until fall?

In June, leafy spurge is one of our most problematic rangeland, pasture, and roadside weeds. It is also one of South Dakota’s noxious weeds that landowners are required by law to control. So should you spray it now or wait until fall?