Potato Leafhopper is Abundant in Alfalfa

Potato leafhopper arrived in the state about three weeks ago, and populations have grown really well in some parts of the state. We have seen strong populations of leafhopper in some alfalfa fields in central Pennsylvania, with some exceeding economic threshold. We have heard similar reports in southeastern Pennsylvania. Growers would be wise to use a sweep net to scout their fields for this pest because once their feeding is evident economic damage has been done.

Potato leafhopper feeding reduces yield and quality (especially lower protein content) and can decrease stand longevity. If damaging populations develop, early harvest or insecticides are often the only choices. Early harvest can stop damage, but regrowth should also be scouted to determine if the next cutting also develops damaging populations. To target leafhoppers most effectively, populations should be sampled and treatment applied only when economic thresholds are exceeded. In my experience, regular scouting and use of economic thresholds can limit the need to use insecticides to once a summer. Scouting details and economic thresholds can be found in our potato leafhopper fact sheet.