RESISTANCE IN BROCCOLI TO BACTERIAL SOFT ROT CAUSED BY PSEUDOMONAS-MARGINALIS AND FLUORESCENT PSEUDOMONAS SPECIES

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-conductive conditions, factors conferring resistance were only indirectly associated with the length of time required for genotypes to reach harvest maturity.