Check your alfalfa fields for potato leafhoppers

Scout alfalfa fields for potato leafhopper Historically, potato leafhoppers exceed economic thresholds in alfalfa fields 5 out of 10 years. Not until 3 years ago did most dairy farmers understand the injury symptoms to watch for. The year I took my leave to work with soybeans, Minnesota alfalfa fields were overcome by potato leafhoppers. Potato leafhoppers populations were estimated to be 30-40 times higher than normal. All alfalfa fields needed to be sprayed at least once that growing season. This year again, leafhoppers are being seen in southern Minnesota at fairly high numbers so begin scouting fields. This is one insect that moves in from states farther south in the spring beginning in mid-May. With the right weather conditions, leafhoppers can move from the gulf states to Minnesota in two days. Potato leafhoppers are relatively small, about the size of an aphid, and a light green color. Adults can fly so they are easily overlooked unless scouting is done with sweep nets. Symp-toms to watch for in alfalfa and edible bean fields are patches in fields where plants turn yellow. Leaves develop V shaped yellow spots often toward the leaf tip. Feeding by potato leafhoppers stunt plants so reduces both quality and tonnage of alfalfa. The following economic thresholds have been established for alfalfa: Alfalfa Height (Inches) – Economic Threshold per Sweep   o 3 0.2   o 6 0.5   o 8-10 1.0   o 12-14 2.0