Harvest with Raking for Control of Alfalfa Weevil (Coleoptera: Curculionidae)

Successful implementation of early harvest techniques for alfalfa weevil larval, Hypera postica Gyllenhal, management depends on synchronization between alfalfa growth sufficient for harvest and economic populations of the insect, conditions that frequently occur in Montana. Field trials were conducted in 1996 and 1997 to determine if the addition of raking to timed harvest would improve the efficacy of alfalfa weevil larvae management, an important cultural control of alfalfa weevil larval populations. Post-baling mean number of alfalfa weevil larvae in stubble were 4.3 (SE = 1.6) and 7.5 (SE = 1.1) per 0.1 m² for cutting with raking and cutting alone, respectively, (P = 0.06). Nutritive value of forage, as estimated by crude protein and neutral and acid detergent fiber concentrations, did not differ between treatments. Harvest combined with early raking effectively reduced alfalfa weevil larvae populations over cutting alone without compromising nutritive value of forage.