Full Season Impact of the Alfalfa Weevil, Meadow Spittlebug, and Potato Leafhopper in an Alfalfa Field123

Abstract

A series of field tests was carried out to identify the effects of alfalfa weevil, Hypera postica (Gyllenhal), meadow spittlebug, Philaenus spumarius (L.), and the potato leafhopper, Empoasca fabae (Harris), on alfalfa growth and recovery. The effects of individual and combined feeding were examined under both natural and controlled conditions by using a replicated factorial design. Alfalfa growth, yield, and rate of maturity were decreased in all 4 cuttings following infestation of the 1st cutting by the alfalfa weevil and meadow spittlebug. The apparent loss in stand attributed to the weevil showed recovery in the 2nd year. The potato leafhopper decreased growth, rate of maturity, and yield of the 3rd cutting with a carry-over effect that delayed maturity in the 4th cutting. Generally, the effects of the 3 insects on the crop were nearly additive. A significant decrease in protein, not associated with the meadow spittlebug, was observed in the 1st cutting due to a high loss in leaves from attack by the alfalfa weevil.