Most damage takes place on second and third cuttings after potato leafhopper populations have had a chance to increase. However, new seedlings, which are especially susceptible to leafhoppers because of underdeveloped root systems, may require earlier and more frequent inspection. Make sweeps while walking through an area by moving the net from side to side in a sweeping motion through the foliage. Count both adult and nymph leafhoppers. After each set of sweeps, measure the height of at least two stems in each area.
Economic thresholds follow.
If leafhopper numbers are at or above threshold levels, the pest can be managed by cutting immediately, provided the crop is close to the normal harvest time. If threshold levels are present, but the alfalfa isn't ready to harvest, Bannon recommends producers consider applying an insecticide. A timely treatment will prevent a yield and quality loss, but early detection is essential. Producers can see significant reductions in crude protein from heavy infestations. Leafhopper damage makes it harder for the alfalfa plant to survive the winter and can reduce the overall life of the stand.