DISEASES, PESTS, AND ABIOTIC PROBLEMS ASSOCIATED WITH ORIENTAL CRUCIFEROUS VEGETABLES IN SOUTHERN ONTARIO IN 1993-1994

A survey of the incidence and severity of diseases, insects, nematodes , and abiotic problems affecting oriental cruciferous vegetables was c onducted in southern Ontario within a 120 km radius of Toronto during repeated visits to growers' fields and greenhouses in 1993 and 1994. T his is the first such survey conducted in the principal area of produc tion of these vegetables in Canada. Downy mildew, pseudocercosporella leaf spot, turnip mosaic (TuMV), soft rot, and alternaria leaf spot we re the most common diseases. The major insects were cabbage maggot, gr een peach aphid, and flea beetles. The former two were associated with substantial losses due to soft rot and TuMV, respectively. Damage due to plant-parasitic nematodes was infrequent. Other problems encounter ed were boron deficiency in Chinese radish, tip burn in Chinese cabbag e, bolting in various crops, petiole ''freckles'' in Chinese cabbage, losses due to weed infestations arising from no or improper herbicide usage, and nonharvested plants due to a shortage of labour or poor mar ket conditions.