Leaf spot. On celery leaf spots round to irregular, sometimes limited by veins, pale to dark brown, often with darker margin, sometimes coalescing to form large blotches.
Morphology
Conidiophores usually arising from brown stromata on lower surface of leaf, in groups of up to 30, olivaceous-brown, usually 20–350 µm long but sometimes much longer especially if plant material has been kept in high humidity, 3–6 µm thick. As conidiophores continue to elongate they produce successive conidia, and hence two or more widely spaced scars. Conidia 30–200 µm long but sometimes longer especially if plant material has been kept in high humidity, 2–5 µm wide, hyaline, 3–25-septate, smooth, acicular, straight or curved, tip rounded, basal cell truncate with a distinct dark scar. On young lesions or under dry conditions the conidia may be smaller and obclavate in shape; the first cell may also taper towards a somewhat rounded base (with dark scar).
