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Symptoms and Control Methods of Bacterial Leaf Spot in Lilies

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Bacterial leaf spot is an important disease of lilies, occurring and distributed in certain regions, and can develop both under protected cultivation and in open fields. Typically 5%-10% of plants are affected, impacting yield and quality to some extent. In severely affected plots, the field incidence rate can reach over 20%, significantly affecting lily production. [Symptoms] This disease can affect all parts of the lily, with symptoms mostly appearing on above-ground parts. Initially, densely packed water-soaked greenish-brown nearly oval small spots appear on the leaves, which later develop into nearly spindle-shaped yellowish-brown to dark brown necrotic lesions, slightly sunken, with water-soaked edges

Bacterial leaf spot is an important disease of lilies, occurring and distributed in certain regions, and can develop both under protected cultivation and in open fields. Typically 5%-10% of plants are affected, impacting yield and quality to some extent. In severely affected plots, the field incidence rate can reach over 20%, significantly affecting lily production.

[Symptoms]

This disease can affect all parts of the lily, with symptoms mostly appearing on above-ground parts. Initially, densely packed water-soaked greenish-brown nearly oval small spots appear on the leaves, which later develop into nearly spindle-shaped yellowish-brown to dark brown necrotic lesions, slightly sunken, with water-soaked greenish-brown edges, merging together into irregular large necrotic patches. When the air is humid, the leaves rot and die within a short period. When the air is dry, the diseased leaves become light brown, necrotic and withered. As the disease progresses, the stems show irregular light brown to yellowish-brown necrosis, and later rot or shrink and dry up.

[Pathogen]

Unknown. Preliminary identification suggests it is a type of bacterium, pending further research.

[Occurrence Pattern]

According to observations, this disease mainly overwinters with seedlings or bulbs, and is transmitted through infected seedlings or infected bulbs. When conditions are suitable, the disease develops and spreads through rain, irrigation water or pests, causing secondary infections and leading to disease expansion and spread. Rainy and humid conditions favor disease development.

[Control Methods]

1. Strengthen quarantine measures to prevent the transportation of infected seedlings and bulbs.

2. Before planting, soak the bulbs in a 500-fold dilution of 47% Kasugamycin+Copper Hydroxide wettable powder, or in a 0.3%-0.5% hydrochloric acid solution for 5-10 minutes.

3. Strengthen field management, and promptly remove diseased plants when found. Avoid flood irrigation, and prevent waterlogging in the field after rain.

4. Apply pesticide sprays promptly in the early stages of disease onset. See Black Rot of Broccoli.

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