Content by Philip Rozeboom

Redlegged, differential, and twostriped grasshopper nymphs.

Various Grasshopper Species Are Active Across South Dakota

While scouting, we have noticed increased grasshopper nymph activity and in some areas these populations are close to threshold levels. Crops in areas that have had high populations should be regularly scouted to ensure that extensive defoliation doesn’t go unnoticed.

A red, weed hoe next to a freshly cut, green weed surrounded by brown soil.

Reminder: Cutoff for over-the-top dicamba products labeled for soybean is June 30 or R1 growth stage in South Dakota

Over-the-top dicamba products for application in soybean have been relabeled for the 2026 growing season. A stipulation for applying these herbicides is a cutoff date of June 30 or R1 soybean.

Bird cherry oat aphids, English grain aphids, Greenbugs.

Aphid Populations Detected in Wheat

Aphids are present in South Dakota wheat fields, and that means it’s time to start scouting.

Collection of insects in a canvas sweep net.

Pea Aphid Alert: Forecasted temperatures could result in rapid population increases

The temperatures during the last week and the forecasted temperatures for next week will potentially encourage rapid pea aphid population growth. Although many fields have been cut recently, pea aphids can still readily recolonize alfalfa.

Multiple weed species growing in a grassy area.

Noxious Weeds Should Be Closely Monitored for Management

Pasture, rangelands and rights-of-way are starting to turn yellow, purple, or even a mix of both due to rapid growth of noxious weeds. Now is the time to implement management tactics to ensure the weeds do not outcompete desirable vegetation and invade adjacent land.

Greenish brown bugs on a white sweep net cloth.

Alfalfa Plant Bugs Showing Up in Abundance

There have been several insect pests showing up in alfalfa this season, including the alfalfa plant bug. We consider the above-average spring temperatures and drought-stressed plants in Eastern South Dakota to be the primary drivers of these issues.

Gray beetle resting on the purple blossom of an alfalfa plant.

Blister Beetles Already Appearing in Alfalfa

Large blister beetles populations were observed while scouting alfalfa this past week. While they usually aren’t an issue until after the first cutting, this early activity means growers should monitor alfalfa fields prior to harvest for the remainder of the season.

Left: Alfalfa weevil larvae. Right: Alfalfa weevil adult.

Alfalfa Weevils Are Active in South Dakota

Alfalfa weevil larvae are active across South Dakota. Although they had a somewhat slower start this year, we are now observing all instars of the larvae in alfalfa fields.

Green leafhopper with clear wings.

Aster Leafhoppers Detected in South Dakota Wheat

Aster leafhoppers are present in wheat again this spring. For the last few years, aster leafhoppers have been a common occurrence in South Dakota wheat.

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

South Dakota Overwintering Bean Leaf Beetle Predicted Mortality: 2025-2026

Each year we evaluate the overwintering success of bean leaf beetles in South Dakota. For adult bean leaf beetles that successfully overwintered, emergence will begin in the spring and they will move into soybean fields.