Occurrence of race 2 of Verticillium dahliae in processing tomato fields in southwestern Ontario

A survey was conducted in 1993 and 1994 to assess the inoculum density of Verticillium dahliae in soil and the incidence of V. dahliae-infected plants in randomly selected sections of 10 processing tomato fields in Essex County, Ontario. Disease incidence was not reliably predicted by the Anderson sampler method of enumerating V. dahliae populations in soil. By early August, an average of 31% to 41% of the plants sampled were infected with Ii. dahliae. V. dahliae isolates collected from soil samples, field-grown tomato and potato plants, and eggplant and tomato trap plants grown in field soil under controlled environmental conditions were tested for pathogenicity on susceptible and race I-resistant tomato cultivars; of 126 isolates tested, 122 were of race 2, and 4 were of race 1.