VIEW ARTICLE

Ecology and Epidemiology

Potato Blackleg in Progeny Plantings from Diseased and Symptomless Parent Plants. M. L. Powelson, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; J. D. Apple, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Phytopathology 76:56-60. Accepted for publication 29 July 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-56.

The incidence of potato stems with blackleg symptoms was studied in plots planted with seed tubers harvested from plants with or without blackleg symptoms. Plots at one location in 1982 and at two locations in 1983 were established with planting material from three different seedlots of early generation stocks of cultivar Russet Burbank. The incidence of stems with blackleg symptoms in plants from five of the six seedlots was significantly lower in progeny originating from symptomless parent plants than from parent plants with blackleg symptoms. However, average incidence of blackleg symptoms was high irrespective of the disease status of the parent plants (e.g., 85% in 1982 and 74.5% in 1983). Erwinia carotovora pv. carotovora was the principal pathogen associated with diseased progeny plants. However, both E. c. pv. atroseptica and E. c. pv. carotovora were isolated from diseased stems in the parent hills. Seed tubers from parent plants with or without blackleg symptoms were contaminated with E. c. pv. carotovora and E. c. pv. atroseptica. In one seedlot in both 1981 and 1982, a greater percentage of tubers from symptomatic parent plants was contaminated with E. c. pv. atroseptica than of tubers from symptomless parent plants. However, tubers from these parent plants with blackleg symptoms did not have signficantly more blackleg symptoms caused by E. c. pv. atroseptica.