Bryan Jensen, UW Extension
Potato leafhoppers populations, to date, have been relatively low. Cool, wet weather has certainly not been conducive but warmer, drier weather could change that in a hurry. So far, I have not had a single call/email regarding leafhopper populations in established stands. However, I would strongly suggest monitoring new seedings. New seedings present a unique problem compared to established stands. After harvest, there is usually enough green foliage available for some nymphs to survive and either for adults to remain within the field or for a new flight to immediately migrate in. In established stands, nymphal mortality is extremely high because of the lack of food and and cover. Adults migrate out of the field for similar reasons. As a result, adult potato leafhoppers must recolonize each field after regrowth has started.
I’m not suggesting we will no longer have problems with potato leafhoppers in established stands but once we reach mid-July the probably of high populations is greatly reduced. However, now is an important time to scout new seedings.