ASSOCIATION OF ERWINIA-CAROTOVORA VAR ATROSEPTICA AND ERWINIA-CAROTOVORA VAR CAROTOVORA WITH INSECTS IN COLORADO

Ten genera from 9 families of dipterous insects collected in the field in the San Luis Valley of Colorado were contaminated with Erwinia carotovora var. atroseptica (Eca) and Erwinia carotovora var. carotovora (Ecc). Erwinia-contaminated insects were collected from settling ponds near potato warehouses, potato cull piles on growers’ farms, municipal dumps, lettuce and potato fields. The percentage of contaminated insects reached 14.5% in early spring but decreased as the season progressed. Insects were more commonly contaminated with Eca than Ecc early in the season. Later the proportion of contamination by Ecc increased while that of Eca decreased. We suggest that insects may play a potentially important role in the epidemiology of potato blackleg especially in the reintroduction of Erwinia into Erwiniafree potato fields. © 1979, Springer. All rights reserved.