The Role of Alternate Plant Hosts in the Aphid Transmission of Bean Mosaics in Central Washington1

Abstract

Studies of alternate plant hosts for bean mosaic diseases found in south central Washington were made from 1955 through 1959. Red clover, sweet clover, and broad bean were susceptible to various of the viruses involved. Green peach aphids, Myzus persicae (Sulzer), and clover aphids, Anuraphis bakeri (Cowen), could transmit some of these viruses from red clover and sweet clover to bean and/or vice versa, and pea aphids, Macrosiphum pisi (Harris), could transmit these viruses from broad bean to bean. Both red clover and sweetclover are grown or occur on roadsides in south-central Washington. Green peach aphids are exceedingly abundant and active during the growing season in this area; clover aphids and pea aphids are numerous. Consequently, it is likely that the yearly recurrence of mosaic infections in field beans in this area is at least partly attributable to alternate plant hosts, such as sweet clover and red clover, in which the virus pathogens may over winter.