Content by Philip Rozeboom
Reports of Pyrethroid Failures for True Armyworm Caterpillar Management
True armyworm caterpillars reached thresholds in oats and wheat in many areas of South Dakota recently. Management efforts to reduce populations had varying levels of success, with SDSU Extension receiving numerous reports of pyrethroid insecticide failures.
Late-Season Crabgrass Control
At the start of August, crabgrass is often prevalent in lawns. Ideally, this weed should be controlled earlier in the season, but if early management was missed, a post-emergence herbicide can help control it before it produces more seed.
Watch for Blister Beetles in Later Alfalfa Cuttings
The frequent rain events experienced this summer has helped boost forage production. Although this is great for growers, the possibility of encountering blister beetles at harvest increases later in the summer.
Strong, Effective Herbicide Programs Can Be Complimented With Narrow Row Spacing
While strong herbicide programs will result in effective weed management, a cultural tactic, such as row spacing can result in a complementary increase in effectiveness.
Bean Leaf Beetles Showing Up in Soybean
Despite the prediction of low overwintering survival we have observed bean leaf beetles in soybean this week. See our latest observations and management recommendations.
EPA Proposes a Decision to Approve Registration for Dicamba Labeling to Be Applied to Tolerant Soybean
Dicamba products previously labeled for overtop application to tolerant soybean are not registered for use during the 2025 growing season. However, the EPA has proposed to re-register these dicamba products for use in tolerant soybean starting in 2026.
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.
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.
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.
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.