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Races, Pathogenicity and Chemical Control of Plasmodiophora brassicae in Ontario. Andres A. Reyes, Thomas R. Davidson, and C. Frank Marks, Research Scientists, Agriculture Canada, Vineland Station, Ontario, Canada L0R 2E0. Phytopathology 64:173-177.

Two races of Plasmodiophora brassicae were identified from 20 isolates in Ontario.  Most race-2 isolates were recovered from rutabaga in sandy soil and race-6 isolates from other crucifers in loam and muck soils.  All cultivars of cabbage, cauliflower, broccoli, and brussels sprouts recommended for commercial production in Ontario were susceptible to races 2 and 6, whereas all radish cultivars resisted infection.  The following cruciferous weeds, Brassica kaber, Camelina microcarpa, Capsella bursa-pastoris, Descurainia sophia, Eruscastrum gallicum, Erysimum cheiranthoides, Lepidium ruderale, Sisymbrium officinale, and Thlaspi arvense were susceptible to race 6.  Benlate was the most effective of the chemicals studied for control of P. brassicae and provided good control in the field when drenched at transplanting and again one mo later.