Phoma diseases (Leptosphaeria maculans and Leptosphaeria biglobosa; asexual stage Phoma lingam), also known as blackleg, are important worldwide in Brassica crops including the leafy and flowerhead types, turnip, Chinese cabbage and pak choi, oilseed rape and swedes and mustard. In the UK, Phoma stem canker of oilseed rape is the most economically important disease in southern, eastern and central England. Severe losses can occur in cauliflower and swede, but it is mainly a leaf blemish on other vegetable Brassicas. Once leaf spots appear, the fungus can grow in the plant without causing any symptoms before causing severe stem symptoms.
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