By Scout Nelson
Farmers are being encouraged to closely monitor alfalfa fields as warmer temperatures may create conditions that support rapid growth of pea aphid populations. Pea aphids can increase quickly when weather conditions are favorable, creating a potential risk for crop health and yield.
Adam Varenhorst, Associate Professor and SDSU Extension Field Crop Entomologist, along with Philip Rozeboom, Amanda Bachmann, and Patrick Wagner, highlighted the importance of monitoring pea aphid populations as temperatures increase. The specialists noted that pea aphid growth is highest when temperatures are near 70 °F, while higher temperatures can reduce population growth.
Many areas have already observed large pea aphid populations in 2026. Although several alfalfa fields have recently been cut, pea aphids can still return and rebuild populations quickly. New plant growth can provide suitable conditions for aphids to increase and affect crop performance.
Regular scouting is an important step in managing pea aphids. Farmers should inspect fields often and track insect numbers to determine whether populations are reaching levels that could harm crop production. Early detection allows growers to make timely decisions and avoid unnecessary crop damage.
If pea aphid populations reach recommended management levels, foliar insecticides can be used as a control option. However, treatments should be based on careful field monitoring and proper recommendations. Applying management practices at the right time can help reduce losses and protect alfalfa quality.
Weather conditions play an important role in insect development. With forecasted temperatures expected to support faster pea aphid growth, continued observation of alfalfa fields is important. Farmers should remain alert and adjust management plans as needed throughout the growing season.
Photo Credit: gettyimages-v_zaitsev
Categories: South Dakota, Crops, Alfalfa, Weather