ABSTRACT
In alfalfa forage production, the importance of foliar growth of plants must be emphasized as it is highly valued by humans for use in feeding livestock. The potato leafhopper, Empoasca fabae (Harris), pea aphid, Acyrthosiphon pisum (Harris), and spotted alfalfa aphid, Therioaphis maculata (Buckton), are among the more common fluid-feeding insects, with potential to cause reduced growth and productivity of alfalfa. Severe infestations of the spotted alfalfa aphid, in particular, can result in death of plants. In a study by Kindler et al., yield reductions caused by the pea aphid and spotted alfalfa aphid were 48% and 38%, respectively. Seasonal occurrence of the blue alfalfa aphid through spring and early summer is quite similar to that of the pea aphid, and fields are often infested by combined populations of these species. A pest management program developed for alfalfa seed production in Washington emphasizes preservation of beneficial predators, parasites, and pollinators.
