Bacterial Wilt of Potatoes in the Amazon Basin. C. Martin, Pathology Department, International Potato Center, Apartado 5969, Lima, Peru. E. R. French, and U. Nydegger, Pathology Department, International Potato Center, Apartado 5969, Lima, Peru. Plant Dis. 65:246-248. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-246.

Bioforms I and II of Pseudomonas solanacearum, considered synonymous with races 1 and 3, respectively, have been isolated from potatoes (Solanum tuberosum) grown in virgin Amazon rain forest following slashing and burning. Race 2, which attacks only musaceous hosts, occurs elsewhere in the Amazon basin. The incidence of bacterial wilt ranged from 5 to 15% in adapted potatoes and from 2 to 13% in unadapted cultivars. Bioform I was isolated in 1975, bioform II in 1977, and both in 1976 and 1978. In one instance, both were found in the same field. Seed tubers were free of P. solanacearum, and contamination by flood waters is discounted. Since bioform II has been shown to have a lower temperature requirement when isolated in the highlands or high latitudes, it may have originated in the lowlands and later acquired this characteristic, as well as its narrow host range restricted essentially to potatoes.