The effect of Erwinia carotovora subsp. atroseptica (blackleg) on potato plants. II. Compensatory growth

Abstract

SUMMARYIn field experiments in 1981 and 1982, uninoculated seed tubers (cv. Désirée) and those inoculated with Erwinia carotovora subsp. atroseptica at the rose (apical) or heel (stolon attachment) ends were planted at normal (35 cm) or double spacing; in additional plots, inoculated and uninoculated tubers were planted alternately.Inoculation, especially at the rose end, decreased plant height and sometimes resulted in blackleg symptoms. Individual plant yields were recorded at the end of the season. In plots of uniform seed type at normal spacing, inoculation decreased total yield compared with uninoculated by 12–13% (heel‐end inoculation) or 26–40% (rose‐end inoculation). At double spacing, yields increased compared with normal spacing by 44–58% (uninoculated or heel‐end inoculation) or 30–39% (rose‐end inoculation). When rose‐end‐inoculated and uninoculated seed tubers were planted alternately, inoculated plants yielded less and uninoculated plants more than in plots planted throughout with the same seed treatment. The abilities of inoculated and uninoculated plants to compensate for weak or missing neighbours were combined using equations to predict the yields of crops with different proportions of diseased or missing plants.