Productivity and persistence of alfalfa in response to clover root curculio (Coleoptera: Curculionidae) injury in Pennsylvania

Clover root curculio, Sitona hispidulus (F.), is a pest of clovers but is often overlooked in alfalfa. This study examined the association between the clover root curculio and alfalfa yield, quality, and persistence in Pennsylvania from 1984 to 1988. Caged and noncaged 9.3-m2 plots were established in a 1-ha alfalfa field to assess this relationship. The cages reduced feeding damage but did not completely, exclude the clover root curculio. In 1987, the percentage of alfalfa coverage was greater in the caged than in the noncaged plots. Alfalfa height in the noncaged plots was reduced 23.2-38.9% at all harvests in 1987, and yields were significantly reduced at 3 harvests. In addition, losses of 800-932 kg/ha per harvest were accompanied by significant increases in weed biomass, which contributed to a reduction in total crude protein. The number of dead alfalfa plants was greater in the noncaged than in the caged plots in April 1988. Our results indicate that clover root curculio affects yield, quality, and stand persistence of alfalfa in Pennsylvania and likely throughout the Northeast