Diseases occurred to plug seedlings of cabbage.

Abstract

The occurrences of damping-off to plug seedlings of cabbage were investigated in a nursery of vegetable seedlings in Mie prefecture on August to November 1997. During the investigation, the disease caused by Alternaria brassicicola (Schweinitz) Wiltshire was found most frequently. Symptoms produced by A. brassicicola were black or gray lesions on cotyledons at early stage of the occurrence and spread to hypocotyl or shoot, then seedlings were damped off. On October and November, damping-off by Pythium megalacanthum de Bary was occurred. The fungus produced water-soaked lesion on hypocotyl and turned it white in dry condition. Diseases on hypocotyl by Rhizoctonia solani Kühn and Phoma lingam (Tode:Fries) Desmazières were found in a few cases. R. solani produced brown lesion. P. lingam made the hypocotyls dry and brown or cream color. Two Fusarium spp. that were not cited as cabbage pathogens, were isolated from damping-off seedlings with brown lesion, and their virulence were recognized. In greenhouses in National Research Institute of Vegetables, Ornamental Plants and Tea, damping-off caused by A. brassicicola, P. megalacanthum and P. lingam were also found. Besides these diseases, damping-off caused by Pythium aphanidermatum (Edson) Firzpatrick was occurred in summer. The symptom looked like that by P. megalacanthum.