What are the control methods for leaf blight of osmanthus trees?
How to control leaf blight in osmanthus trees? Please introduce and guide. Leaf blight is a common disease in osmanthus cultivation. Its symptoms: it occurs at the leaf margins and leaf tips. It starts as small light brown spots, then gradually expands into irregular large patches. If several lesions connect, the entire leaf dries up by 1/3-1/2. The lesions are grayish brown to reddish brown,...
How to control leaf blight in osmanthus trees? Please introduce and guide.
Leaf blight is a common disease in osmanthus cultivation. Its symptoms: it occurs at the leaf margins and leaf tips. It starts as small light brown spots, then gradually expands into irregular large patches. If several lesions connect, the entire leaf dries up by 1/3-1/2. The lesions are grayish brown to reddish brown, sometimes brittle and cracked, with a darker, slightly raised edge. Later, many small black dots are scattered on the diseased parts, and the color on the underside of the lesions is lighter. Transmission route: the pathogen overwinters as mycelium or pycnidia in diseased leaves and fallen diseased leaves, and conidia spread through wind and rain. The optimum temperature for pathogen development is around 27°C. When potted plants are kept in a humid, stuffy place with poor ventilation, or when the plants grow weakly, the disease will worsen. The disease occurs more often on old leaves after winter. It occurs more often on the lower leaves of the plant.
Control methods
1. Horticultural control
Strengthen cultivation management. Potted osmanthus should avoid waterlogging, and more humus fertilizer and potassium fertilizer should be applied to improve disease resistance. Diseased leaves should be promptly removed from diseased plants, and fallen diseased leaves should also be cleared in winter to reduce sources of infection.
2. Chemical control
During the onset of the disease, Bordeaux mixture with double the amount of lime at 1:2:100 can be sprayed at the initial stage, and afterward 50% benomyl wettable powder at 1000-1500 times dilution, or 50% carbendazim at 800-1000 times dilution, can be sprayed for control.
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