The alfalfa weevil is a major spring insect pest of South Dakota alfalfa. Before 2018, this insect was reported as having large populations throughout much of South Dakota. However, during 2018 and 2019, we received fewer reports of alfalfa weevils, which may have been a result of the cooler and wetter spring conditions that were observed.
During the last week, the colder weather that we experienced across South Dakota resulted in very little degree day accumulation. However, in some areas enough degree days have accumulated to potentially lead to adult activity within alfalfa fields.
It is finally warming up across much of South Dakota and that means the degree days are beginning to accumulate more rapidly. Alfalfa weevil activity is likely in areas around Rapid City, Hot Springs, Cottonwood, Mission, Pierre, Winner and Vermillion.
Although bean leaf beetles won’t be emerging for a while yet, it is important to be prepared for potential early season defoliation. Once soybean are planted and begin emerging, the overwintering population of bean leaf beetle adults will move into soybean fields and begin feeding on the seedlings.
Spring green-up is the time to be watching for black grass bug activity. Large populations of this early-season pest can cause severe damage to pasture (up to 90% forage reduction) and infest the edges of wheat fields.
Fact sheet about insecticide treatment options for protecting ash trees against emerald ash borer.
With their distinctive black and yellow stripes and tendency to hang out in groups, wasps receive attention no matter the time of year. As the weather warms up and spring progresses, you may notice more wasp activity in your yard or around your house.
Before mixing any pesticide always check the pesticide label for instructions on compatibility of two or more pesticides. Some herbicides and carriers require a compatibility agent, some are not compatible with a compatibility agent.
Temperatures continue to increase across South Dakota and the degree days are rapidly accumulating. With the exception of areas around Selby, Sisseton and Brookings, alfalfa weevil activity is likely in South Dakota.
Although the majority of winter wheat in the state is rated good to excellent in the recent USDA-NASS report, a few winter wheat fields in Central South Dakota have been diagnosed with wheat streak mosaic disease (WSMD) caused by wheat streak mosaic virus (WSMV).