Differential grasshopper on defoliated alfalfa.
Foliage may be destroyed by grasshoppers from May until frost. It is easier to control nymphs than adults. Young stands less than 6 inches high or the post-cutting regrowth of established plantings may need to be protected with an insecticide. Repeated applications may be required because labeled products have short residual properties.
Treatment of non-field border areas with suitably registered products may be warranted if grasshoppers begin moving into the field in increasingly large numbers as permanent vegetation bordering alfalfa matures and dries down. The extended interval associated with growing and harvesting seed alfalfa can elevate the importance of controlling grasshopper damage to protect developing blossoms and seedpods.
Please refer to the most recent Alfalfa Insect Management Guide for specific control options.