Much of the second cutting is off and recent rains have the regrowth coming
back strong. Some recent sweeps that I've taken show surprisingly few potato
leafhopper in some of this regrowth. HOWEVER, this situation can
change in a hurry. Potato leafhoppers cause some big losses to alfalfa
fields in Wisconsin most every year. Last year was one of the worst in
recent memory. Once you can see the damage (the characteristic yellow
"hopperburn" on leaf tips) it's too late to do anything about it.
To assess the potential for damage, use a 15-inch diameter sweep net and
take 5 sets of 20 pendulum-style sweeps throughout the upper portions of
plants. Use the table below to see if insecticide applications are economical.
For more information and images of the potato leafhopper, check out Potato
Leafhopper - Biology and Control from North Dakota State University.
If you have seeded one of the glandular-haired varieties, see this
recent article by John Wedberg, UW Extension Entomologist.
