How to prevent and control eucalyptus purple leaf spot? Detailed explanation of prevention and control methods
How to prevent and control purple leaf spot in eucalyptus? Please explain the methods. Eucalyptus purple leaf spot is a relatively common leaf disease in eucalyptus planting areas. It affects various species of the genus Eucalyptus. It occurs in Yunnan and Guangdong in China. Symptoms: In the early stage of the disease, scattered or relatively densely clustered spots appear on both sides of infected leaves. The lesions are polygonal or irregular, purple...
How to prevent and control purple leaf spot in eucalyptus? Please explain the methods
Eucalyptus purple leaf spot is a relatively common leaf disease in eucalyptus planting areas. It affects various species of the genus Eucalyptus. It occurs in Yunnan and Guangdong in China.
Symptoms: In the early stage of the disease, scattered or relatively densely clustered spots appear on both sides of infected leaves. The lesions are polygonal or irregular, purple. The lesions may join together into patches. In the later stage of the disease, small granular protrusions form on the lesions; these are the pycnidia of the pathogen. When a large number of spores are produced in spring, dark brown or nearly black tendril-like cirrhi of conidia form a black sooty mold-like substance on the leaf surface, similar to the symptoms of sooty mold diseases.
Pathogen: The pathogen is Coniothyrium-kernel-like brown septate spore fungus belonging to the subdivision Deuteromycotina, class Coelomycetes, order Sphaeropsidales.
Disease occurrence pattern: In the Kunming area, purple leaf spot can be seen year-round. In early to mid-March, the pycnidia mature, and cirrhi overflow in large quantities, covering part or even most of the diseased leaf surface with a thin sooty layer. In Yongsheng County in the Lijiang area, sooty mold-like symptoms are still very common in December. Although purple lesions can be seen on diseased leaves in Kunming in winter, conidia are rarely found.
Prevention and control: 1) Reduce sources of infection: promptly remove diseased leaves and fallen leaves, and destroy them in a centralized manner. 2) Strengthen tending and management, especially for young trees, so that they grow robustly and enhance disease resistance. 3) Chemical control: in the early stage of the disease, spray young trees with 1:1:100 Bordeaux mixture.
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