Aphid Transmission of Bean Viruses in Field Beans in Central Washington1

Abstract

Epidemiology studies of bean mosaic diseases in central Washington were made from 1955 to 1959. Surveys of aphid populations and mosaic disease symptoms were made in plots of field beans. Aphids rarely colonized the bean plants, but moderate to large populations of alate aphids were present from late June until sometime in August. The majority were green peach aphids, Myzus persicae (Sulzer). The bulk of the remainder consisted of pea aphids, Macrosiphum pisi (Harris), and English grain aphids, Macrosiphum granarium (Kirby). Possible arthropod vectors other than aphids were very few. Mosaic symptoms began appearing in the bean plots in July and were well distributed by early August. A number of different nonpersistent viruses were isolated and subjected to greenhouse tests. All were readily transmissible by the green peach aphid and somewhat less so by the clover aphid, Anuraphis bakeri (Cowen). None were transmitted by the English grain aphid. The pea aphid transmitted these viruses only from broad bean. It was concluded that virus spread in the bean fields was due to migrant aphids, especially the green peach aphid, and, because of the short transmission feeding times, vector control methods would likely be of little value in controlling the mosaic diseases.