Leafhoppers are sucking insects and feed on the sap from alfalfa plants and cause yellowing and stunts plant growth. Very young alfalfa plants and plants in early stages of regrowth are the most susceptible to leafhopper damage. Infestation is most likely to occur prior to the second and third cutting of alfalfa in most areas, and in the first cut if it has been delayed. Warm, dry spring weather is much more conducive to leafhopper infestation than is cool, wet spring weather. Damaging populations may be more likely when temperatures are between 70 and 90 F., and particularly when harvest is delayed.
Leafhoppers typically migrate from the edge of the field inward.
Simply put - very significant and extremely costly damage. Literally millions of dollars are stolen from alfalfa growers each year by leafhoppers in terms of lost yield and quality. Established Stands Studies have shown the average loss from an existing stand of alfalfa is 500 pounds per acre per harvest where infestation exists. The loss from new seedings is even more substantial than that from established stands. The loss is not limited to just annual yield reduction.