Resistance in Broccoli to Bacterial Soft Rot Caused by Pseudomonas marginalis and Fluorescent Pseudomonas Species. C. H. Canaday, Assistant Professor, Department of Entomology and Plant Pathology, University of Tennessee, West Tennessee Experiment Station, Jackson 38301-3200. J. E. Wyatt, and J. A. Mullins. Associate Professor, Department of Plant and Soil Science; and Professor, Department of Agricultural Engineering, University of Tennessee, West Tennessee Experiment Station, Jackson 38301-3200. Plant Dis. 75:715-720. Accepted for publication 14 January 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0715.

Significant differences in susceptibility of broccoli (Brassica oleracea var. italica) genotypes to bacterial soft rot (head rot), caused by Pseudomonas marginalis (P. fluorescens biovar II) and other fluorescent Pseudomonas spp., were observed in four field studies from 1986 to 1989. Cultivars Green Defender and Shogun consistently appeared highly resistant to bacterial soft rot. High disease resistance was observed in 1989 in experimental line NVH 521. Cultivar Green Valiant was rated moderately resistant. Both disease incidence and severity were inversely correlated with the number of days from transplanting until harvest. Because resistance was observed even when heads of susceptible and resistant genotypes matured simultaneously under disease-conducive conditions, factors conferring resistance were only indirectly associated with the length of time required for genotypes to reach harvest maturity.