One article to fully understand what southern magnolia brown spot disease is
What is southern magnolia brown spot disease? Please provide an introduction. Southern magnolia brown spot disease, 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 outbreaks in Suzhou, Nanjing, Wuhan, Shenzhen, Tianjin, Shenyang and other places. The symptom is that the pathogen mainly infects the leaves. The surface of diseased leaves...
What is southern magnolia brown spot disease? Please provide an introduction
Southern magnolia brown spot disease, 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 outbreaks in Suzhou, Nanjing, Wuhan, Shenzhen, Tianjin, Shenyang and other places. The symptom is that the pathogen mainly infects the leaves. On the surface of diseased leaves, small light brown or yellow spots first appear, and once they enlarge they become round or irregular lesions, 5-12 mm in diameter, with dark brown edges and grayish-white centers, on which many small black dots grow. The lesions can merge with each other to form irregular large necrotic damage. When the disease is severe, it often causes a large amount of leaf drop and affects the landscape. The pathogen is: the disease generally begins in summer, and the damage is more severe in August-September.
Prevention and 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 the tree vigor and improve disease resistance.
2. Whether in courtyards or street green belts, diseased fallen leaves must be promptly removed and destroyed in a centralized manner. For nursery stock, even more attention should be paid to sanitation management, and diseased leaves should be picked off as early as possible to reduce sources of infection.
3. In the early stage of the disease each summer, a 1:1:100 Bordeaux mixture can be sprayed for protection. Afterwards, 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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