What are the control methods for southern magnolia leaf blight?
How do you control southern magnolia leaf blight? Please give guidance. Southern magnolia leaf blight: 1. Symptoms: The leaf blight pathogen mainly infects leaves. On the surface of diseased leaves, light brown or yellow small spots first appear, which later expand into round or irregular lesions, 5-12 mm in diameter, with dark brown edges and grayish-white centers, on which many small black dots are borne...
How do you control southern magnolia leaf blight? Please give guidance
Southern magnolia leaf blight:
I. Symptoms: The leaf blight pathogen mainly infects leaves. On the surface of diseased leaves, light brown or yellow small spots first appear, which later expand into round or irregular lesions, 5-12 mm in diameter, with dark brown edges and grayish-white centers, on which many small black dots are borne. Adjacent lesions can merge with each other to form irregular large necrotic areas. The disease generally begins in summer, and the damage is more severe from August to September.
II. Pathogen and current disease situation: Southern magnolia leaf blight, also known as spot disease, is a common disease of southern magnolia. It occurs in all areas of China where southern magnolia is cultivated, with more severe occurrence in Suzhou, Nanjing, Wuhan, Shenzhen, Tianjin, Shenyang and other places. When leaf blight is severe, it often causes a large amount of leaf drop, affecting the landscape.
III. Control methods:
1. Southern magnolia should be planted in places with fertile soil and sufficient sunlight. On poor soil, fertilizer should be appropriately increased to strengthen tree vigor and improve disease resistance.
2. Whether in courtyards or street green belts, diseased fallen leaves must be removed promptly and destroyed in a centralized manner. For nursery stock, sanitary management should be paid even more attention, and diseased leaves should be picked off as early as possible to reduce sources of infection.
3. In the early stage of leaf blight each summer, Bordeaux mixture at 1:1:100 dilution can be sprayed for protection. Afterwards, Penkejun at 800-1000 times dilution, 50% thiophanate-methyl wettable powder at 800 times dilution, or 75% chlorothalonil wettable powder at 800-1000 times dilution can be sprayed to control the spread of the disease.
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