powdery mildew on parsley

agriculture and biology blight closeup control crispum danger disease diseased downy erysiphe farming flower foliar fungi fungicide fungual fungus garden gardening green grow heraclei home infection infest leaf macro microorganism mildew mold mould nature outbreak parasite parsley pathogen pathology pest pesticide petroselinum phytopathology plague plant problem protection pustules repellent science spores spot summer symptoms terrace