It is time to have your sweep net out and be scouting for potato leafhopper (PLH) in your alfalfa field. The recent rains have brought PLH into our region from the south where they overwinter. So, get that sweep net out and start checking to see if they are in your alfalfa fields. The piercing and sucking feeding of PLH means that their feeding isn’t obvious and damage (stunted plants and yellowing leaves) won’t show up until a few weeks after feeding. Consequently, scouting with a sweep net is the best method to determine when you need to spray.
IPM of PLH requires knowing the value of the silage or hay. Below is the updated threshold chart with higher values than in older charts.
Source:psu.edu