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Key Points for Integrated Control of Powdery Mildew on Schisandra chinensis

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1. Field symptoms Powdery mildew mainly damages the leaves of Schisandra chinensis, and in severe cases the fruit, petioles and stems are also affected. In the early stage of leaf infection, small white powdery mildew spots appear, gradually expanding and merging into patches, and the mildew layer thickens, like a layer of flour scattered on the leaf surface. On the underside of the mildew spots, small chlorotic spots initially form, expanding into irregular patches as the disease develops. In the late stage of the disease, black particles are produced in the mildew layer, causing moldy staining and fruit drop, reducing yield while also lowering quality. 2. Disease occurrence The powdery mildew pathogen of Schisandra chinensis belongs to the genus Erysiphe in the Ascomycota, and the conidia are mostly cylindrical, with a few being cylindrical-columnar, elliptical or long-oval. In the Fengcheng area, the pathogen overwinters as cleistothecia on diseased plant residues, and in May to June of the second year produces ascospores and conidia for infection, with July to August being the peak period of disease occurrence. The disease can occur at temperatures of 20-28°C, with 25-26°C being the most suitable. The disease is severe in mountainous areas above 1000 m in altitude; it is severe where management is poor, nitrogen fertilizer is applied excessively, and planting is too dense; 1-2 year old Schisandra chinensis plants are lightly affected, while those over 3 years old are severely affected.

1. Field symptoms Powdery mildew mainly damages the leaves of Schisandra chinensis, and in severe cases the fruit, petioles and stems are also affected. In the early stage of leaf infection, small white powdery mildew spots appear, gradually expanding and merging into patches, and the mildew layer thickens, like a layer of flour scattered on the leaf surface. On the underside of the mildew spots, small chlorotic spots initially form, expanding into irregular patches as the disease develops. In the late stage of the disease, black particles are produced in the mildew layer, causing moldy staining and fruit drop, reducing yield while also lowering quality.

2. Disease occurrence The powdery mildew pathogen of Schisandra chinensis belongs to the genus Erysiphe in the Ascomycota, and the conidia are mostly cylindrical, with a few being cylindrical-columnar, elliptical or long-oval. In the Fengcheng area, the pathogen overwinters as cleistothecia on diseased plant residues, and in May to June of the second year produces ascospores and conidia for infection, with July to August being the peak period of disease occurrence. The disease can occur at temperatures of 20-28°C, with 25-26°C being the most suitable. The disease is severe in mountainous areas above 1000 m in altitude; it is severe where management is poor, nitrogen fertilizer is applied excessively, and planting is too dense; 1-2 year old Schisandra chinensis plants are lightly affected, while those over 3 years old are severely affected.

3. Control methods The following control methods are mainly adopted for Schisandra chinensis in Fengcheng City: ① Agricultural control: strengthen field management, balance fertilization, avoid excessive dense planting, improve ventilation and light penetration, and in autumn and winter remove dead branches and fallen leaves from the field and burn diseased plant residues in a centralized manner. ② Chemical control: during the disease period, spray evenly with 12.5% Guolei emulsifiable concentrate at 5000-6000 times dilution, or spray evenly with 10% high-penetration Qingjunting at 1000 times dilution, spray evenly with 33% Wuxiuyuan at 800 times dilution, or spray evenly with 30% kresoxim-methyl at 20-40 g per mu mixed with water.

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