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.
Current events have made decisions around crop options very difficult this spring. Field peas are an option that may have a fit for some producers.
On April 16, NOAA’s Climate Prediction Center released their climate outlook for May and the coming three-month period of May through July. There is a lot of uncertainty in the temperature outlook for the next one-to-three months in the Northern Plains Region.
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.
Spring is a busy time for South Dakota farmers and ranchers with planting, calving, and other field preparations. Soil sampling and fertilizing pastures, alfalfa, or other forages might be overlooked.
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.
Soil temperature is an important consideration for deciding when to begin planting spring crops. If producers in South Dakota would like a quick reference for soil temperatures in their area, the SD Mesonet network measures soil temperature at several weather stations throughout the state.