Etiology and management of Fusarium crown and root rot (Fusarium oxysporum) on greenhouse pepper in Ontario, Canada

Infection of greenhouse pepper plants (Capsicum annuum L.) by Fusarium oxysporum was observed in two commercial operations in Ontario, causing plant death and yield losses. The pathogen was identified based on cultural, morphological and pathogenicity tests supplemented by PCR amplification of TEF primers. Following inoculation, symptoms of mild stunting occurred within 5–6 weeks, followed by more severe stunting later. Other symptoms, such as chlorosis, wilting and necrosis of the lower foliage, did not become readily evident until about 60 days after inoculation. At 77 days after inoculation, there was considerable brown-black discolouration and decay of crown tissue but little internal stem discolouration or damage beyond the crown portion was observed. Roots were dark brown to black, severely decayed, and easily separated from the surrounding rock wool medium. The fungus was not pathogenic to greenhouse tomato, cucumber or eggplant, nor to field crops such as bean, chickpea or zucchini squash. There were no significant differences in virulence among isolates but differences in resistance/susceptibility among pepper cultivars were observed. The fungicides Medallion® (fludioxonil) and Senator® (thiophanate-methyl) were as effective as bio-control products Mycostop® (Streptomyces griseoviridis) and Prestop® (Gliocladium catenulatum) in limiting Fusarium crown and root rot in greenhouse pepper. Aspects of an integrated disease management strategy are discussed.