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-infec ted plants in randomly selected sections of 10 processing tomato field s in Essex County, Ontario. Disease incidence was not reliably predict ed by the Anderson sampler method of enumerating V. dahliae population s in soil. By early August, an average of 31% to 41% of the plants sam pled were infected with Ii. dahliae. V. dahliae isolates collected fro m 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-re sistant tomato cultivars; of 126 isolates tested, 122 were of race 2, and 4 were of race 1.