Worldwide distribution. Plants in cabbage family, particularly, Chinese cabbage, cauliflower, turnip, mustard, and related weeds. Common fungal disease, but only occasionally severe.
Leaf spots round to angular, up to 8 mm diameter, pale brown or white with a dark brown margin.
Spread in rain and wind; survives in trash, on volunteer plants, weeds and seed.
Cultural control: certified seed; nursery hygiene: clean trays, pasteurise soil or use soilless mixes; weed, remove volunteers; avoid overlapping crops, or plant new crops far from old; collect and destroy debris after harvest; crop rotation.
Chemical control: treat seed with captan, thiram or mancozeb (if not certified); in field use chlorothalonil, copper or mancozeb.