How to prevent and control magnolia leaf blight? Master these practical methods
How to prevent and control magnolia leaf blight? Please give an introduction. The main symptoms of magnolia leaf blight occur on the leaves, and in severe cases can spread to the petioles and flower buds. The lesions mostly occur at the leaf margins, initially appearing as faded green yellow spots, water-soaked, with numerous lesions joining together into patches, expanding outward in a fan shape, with dark brown edges and grayish-yellow interiors, which can cause...
How to prevent and control magnolia leaf blight? Please give an introduction
The main symptoms of magnolia leaf blight occur on the leaves, and in severe cases can spread to the petioles and flower buds. The lesions mostly occur at the leaf margins, initially appearing as faded green yellow spots, water-soaked, with numerous lesions joining together into patches, expanding outward in a fan shape, with dark brown edges and grayish-yellow interiors, which can cause early defoliation. In humid environments, black-gray granular substances appear on the fallen leaves.
Causes of the disease: This disease is a fungal disease; the pathogen survives in leaf buds and on diseased plant residues, spreads via air currents, and can directly infect and damage through the stomata of leaves that are weak in growth or have suffered physiological damage. Damaged leaves and environmental conditions with high wind speed and low air humidity are conducive to the occurrence of the disease, and the disease is severe under high temperature and dry environments.
Control methods: When the flower buds and leaf buds have not yet unfolded, spray the branches and trunk with 3 to 5 degrees Baumé lime sulfur mixture. Where conditions permit, windbreaks (wind protection facilities) can be set up in winter to avoid the occurrence of physiological diseases. In spring, increase foliar water spraying to improve the air humidity of the microenvironment. In the early stage of the disease, spray chlorothalonil and carbendazim fungicides at 800 times dilution.
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