David Owens, Extension Entomologist, owensd@udel.edu
Alfalfa
Potato leafhopper are present in alfalfa. Cutting alfalfa will destroy nymphs, but adults will leave fields for nearby hosts. Take 10 sweeps in 10 locations. If alfalfa is at 60% bud or flowering, harvest fields within the next week if leafhopper counts are high. Plants less than 12 inches tall may be injured by PLH. Thresholds per 100 sweeps vary between 16 and 70-80, depending on plant height between 3 and 12 inches.
Begin scouting for blister beetles in flowering alfalfa. There are a couple of species that are commonly found in alfalfa. All are cigar shaped and with a prothorax that is narrower than both the head and the abdomen giving them a distinctive ‘neck’. Blister beetles can be highly toxic to horses and should be avoided when cutting hay. There are no thresholds for blister beetles. Insecticides can reduce live blister beetles, but if the dead insect does not fall completely out of the canopy, it could still cause problems in the cut forage. Nebraska’s Gary Stone writes that ‘haying equipment without conditioners has shown to reduce the number of dead beetles. If hay is harvested in this manner and allowed to dry in windrows, the majority of beetles can move out. Sickle bar mowers however will crush the beetles. Blister beetles tend to be more concentrated near field edges.
Soybean
Right now, soybean insect pests are fairly quiet. I fear that this may be a mite year, scout field edges, particularly those near tax ditches, pivot points, and field edges with pokeweed.