Lily gray mold (Botrytis elliptica Cooke)

Commonly known as lily leaf blight. It mainly damages leaves, and also infects stems, flowers, buds and bulbs. Leaf lesions are round or oval, yellowish-brown or reddish-brown, with the center of the lesion pale yellow or light brown and the edge purplish-red or pale red. In humid weather, gray mold grows on the diseased parts; when dry, the lesions become thin and brittle, semi-transparent, light gray. After the lesions expand, the leaves die, and affected buds and flowers look as if scalded by boiling water, turning brown and then rotting. When stems are affected, light brown canker spots form, and they break easily in the wind. After young plants are infected, the growing point usually dies, and sometimes the bulbs are also infected, which can cause the bulbs to rot. The lily gray mold pathogen mainly survives unfavorable conditions as sclerotia. In spring, conidia are produced from the sclerotia and spread rapidly in the field by rain, wind and airflow, causing damage. It begins in early May and peaks from late May to late June. Temperatures are high during this period, and if there is prolonged rainy weather, the disease spreads even faster. Long rain followed by clearing and thunderstorms can promote the spread of the disease. Applying unrotted organic fertilizer, excessive nitrogen fertilizer, and low-lying waterlogged areas all favor the onset of the disease.