Home › Nursery Stock › Article

Introduction to Brown Spot Disease of Southern Magnolia

Nursery Stock 0 views
Symptoms: The pathogen mainly infects the leaves. On the surface of diseased leaves, small light brown or yellow spots first appear, then 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 may merge with each other into irregular large necrotic areas. The disease generally begins in summer, and damage is more severe in August-September. Pathogen and current disease status: Southern magnolia brown spot disease, also known as leaf spot disease, is a common disease of southern magnolia. It occurs in all regions of China where southern magnolia is cultivated, with more severe occurrence in Suzhou, Nanjing, Wuhan,

Symptoms: The pathogen mainly infects the leaves. On the surface of diseased leaves, small light brown or yellow spots first appear, then 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 may merge with each other into irregular large necrotic areas. The disease generally begins in summer, and damage is more severe in August-September.

Pathogen and current disease status: Southern magnolia brown spot disease, also known as leaf spot disease, is a common disease of southern magnolia. It occurs in all regions of China where southern magnolia is cultivated, with more severe occurrence in Suzhou, Nanjing, Wuhan, Shenzhen, Tianjin, Shenyang and other places. When the disease is severe, it often causes a large amount of leaf drop, affecting the landscape.

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 centrally destroyed. For nursery stock, even more attention should be paid to sanitation management, and diseased leaves should be removed as early as possible to reduce sources of infection.

3. In early summer each year, at the initial stage of disease onset, a 1:1:100 dilution of 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.

Related Articles