· Numbers of potato leafhoppers in alfalfa are still high.
· Watch for symptoms of potato leafhopper injury to soybean leaves.
Much has been said already about the intensity of infestations of potato leafhoppers in alfalfa. Many people have reported finding large numbers of these pests causing noticeable and, in some instances, excessive damage. Spraying to control potato leafhoppers in alfalfa has been ongoing throughout much of June.
However, don't forget that potato leafhoppers can cause injury to soybeans, too. Although the extent of injury to soybeans caused by leafhoppers is still debatable, noticeable injury will catch your attention. The symptoms of leafhopper injury to soybean leaves are similar to symptoms of injury to alfalfa. The edges of injured leaves turn yellow and may eventually appear burned. Injured leaves may pucker or curl up, and severely damaged rows may be stunted. Soybean fields most at risk are those adjacent to or near alfalfa fields that have been cut. However, if densities of potato leafhoppers are high this year, some soybean fields not even within sight of an alfalfa field could be injured. So stay alert.
Economic losses caused by potato leafhoppers feeding on vegetative-stage soybeans probably are not common. However, the presence of leafhoppers in soybeans bears watching. For susceptible varieties, control in blooming soybeans may be warranted when you find six or more leafhoppers per plant. During early seed formation, control may be warranted if you find 13 or more leafhoppers per plant. Stay tuned to find out if economic infestations of potato leafhoppers develop in soybeans.--Kevin Steffey