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Lily Leaf Blight: Control Methods and Key Technical Points

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Symptoms: Circular or oval lesions form on the leaves, varying in size, with a length of 2 to 10 mm or more. They range from pale yellow to light brown. In some varieties, the spots are light brown, surrounded by a distinct reddish-purple margin, and under humid conditions the spots quickly become covered with a layer of gray mold. When dry, the lesions become thin, easily crumble, are transparent, and generally appear grayish-white. In severe cases, the entire leaf dies. When the stem is infected, it rots and breaks at the point of infection, and the buds turn brown and rot. Spots on the flowers are brown and, when moist, quickly become a sticky mass covered with a gray

Symptoms: Circular or oval lesions form on the leaves, varying in size, with a length of 2 to 10 mm or more. They range from pale yellow to light brown. In some varieties, the spots are light brown, surrounded by a distinct reddish-purple margin, and under humid conditions the spots quickly become covered with a layer of gray mold. When dry, the lesions become thin, easily crumble, are transparent, and generally appear grayish-white. In severe cases, the entire leaf dies. When the stem is infected, it rots and breaks at the point of infection, and the buds turn brown and rot. Spots on the flowers are brown and, when moist, quickly become a sticky mass covered with a layer of gray mold. When young plants are infected, the growing point usually dies. However, in summer the plant may regrow.

Pathogen: The pathogen is a fungus of the genus Botrytis, Botrytis elliptica (Berkeley) Cooke. The conidia are oval. Sometimes Botrytis cinerea Pers. can also harm lilies, but it mainly causes flower rot.

Transmission route: The fungus overwinters as mycelium or sclerotia on fallen diseased plant debris, and the following year produces conidia that infect and cause damage. It can cause repeated infections multiple times. In greenhouses that are excessively humid, the disease occurs easily. When plants are too densely planted, the disease is severe, and excessive application of nitrogen fertilizer makes the disease severe.

Control methods:

1. Horticultural control: In autumn, remove and destroy the aboveground parts of plants cultivated outdoors. Remove diseased leaves at the early stage of the disease to reduce sources of infection.

2. Greenhouses should be ventilated and have sufficient light. Watering should be done at a time when moisture on the leaves dries easily, preferably by watering from the edge, avoiding wetting the leaves.

3. Chemical control: You may choose 50% carbendazim or 70% carbendazim or 70% thiophanate-methyl wettable powder at 500 times dilution. If necessary, you may choose 50% procymidone or 50% iprodione and 50% vinclozolin wettable powder at 1000 to 1500 times dilution plus 80% carbendazim wettable powder at 600 times dilution for a good effect. Spray 40 to 50 kg of the solution per 667 sq m each time. Focus on spraying the newly grown leaves and the surrounding soil surface, and spray continuously 2 times.

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