Leaf Curl causes malformed cupped-leaves, downward curled leaves, the
development of lesions on the stalks and eventually twisting of the
stalks. The disease symptoms are similar to symptoms of several other
diseases of celery. Infected celery plants are not marketable. (Clicking on the picture below will enlarge it.)
An OMAFRA vegetable blog
suggests that fungicides with action against early and late blight of
celery may also have action against leaf curl. For information on
fungicides registered for celery in Nova Scotia see the Guide to Pest Management in Celery beginning on page 10.
Michigan State University Extension has published an very informative article, Celery Anthracnose: a newly identified fungal disease of celery, which includes a number of pictures and frequently asked questions.