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. Potato leafhoppers thrive in dry weather and when temperatures are between 70 to 90 degrees Fahrenheit. Resistant Varieties Growers can also choose to plant alfalfa varieties with resistance to potato leafhopper as another effective way to reduce forage losses to this pest. Research at Iowa State University indicates that in established stands, leafhopper resistant alfalfa varieties may be able to tolerate three to five times higher threshold levels than conventional varieties. While newer varieties with leafhopper resistance offer improved resistance and yield potential, each grower should assess his or her operation to determine the best approach.