DiseasemediumJun–Sep

Carrot leaf blight (Alternaria)

Alternaria dauci

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How to spot it

Carrot leaf blight is caused by the fungus Alternaria dauci and is one of the most common leaf diseases on carrots and related umbellifers. You can recognise it by the blackish brown, irregular spots on the leaflets, which spread quickly in wet weather and cause the foliage to dry up. With a heavy infestation the tops die back so far that harvesting becomes difficult, while the root itself usually stays undamaged.

Prevention

Choose robust varieties and move carrots and other umbellifers to a different spot over several years, so that the pathogen cannot build up in the soil. Do not plant too densely, so the foliage dries off quickly after rain, and water close to the ground rather than over the leaves. Remove infested foliage and crop residues from the bed consistently to lower the infection pressure for the coming season.