Lily gray mold (Botrytis elliptica Cooke)

Commonly known as lily leaf blight. It mainly damages leaves, but also infects stems, flowers, buds and bulbs. Leaf spots are round or oval, yellow-brown or red-brown, with the center of the spot light yellow or light brown and the edge purplish red or pale red. When the weather is humid, a gray mold layer grows on the diseased part; when dry, the spots become thin and brittle, semi-transparent, and light gray. After the spots 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 very 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 through rain, wind and airflow, causing damage. The disease begins in early May and develops severely from late May to late June. During this period the temperature is high, and if there is prolonged cloudy and rainy weather, the disease spreads even faster. Long rain followed by clearing and thunderstorms can promote the spread of the disease. Applying undecomposed organic fertilizer, excessive nitrogen fertilizer, and waterlogging in low-lying areas all favor the occurrence of the disease.