How to prevent and control mango powdery mildew? A detailed guide to practical methods
How to prevent and control powdery mildew when growing mangoes? Please explain the methods. Powdery mildew is an important disease of mango during the flowering period, affecting flower panicles, young fruit and tender leaves. It occurs in producing areas in Guangdong, Hainan, Yunnan, Guangxi and other parts of China. It has also been reported in India, Pakistan, Brazil, South Africa, Australia, Sri Lanka and other countries abroad...
How to prevent and control powdery mildew when growing mangoes? Please explain the methods
Powdery mildew is an important disease of mango during the flowering period, affecting flower panicles, young fruit and tender leaves. It occurs in producing areas in Guangdong, Hainan, Yunnan, Guangxi and other parts of China. It has also been reported in India, Pakistan, Brazil, South Africa, Australia, Sri Lanka and other countries abroad. Symptoms Mango powdery mildew mainly affects flower panicles and tender leaves, and also affects fruit; the symptoms are basically the same: on the affected organs, scattered small powdery white patches first appear, which then gradually expand and merge with one another to form a layer of white powdery mold, and the tissue beneath the mold layer gradually turns brown and necrotic. Flower panicles The flower stalks and sepals are the most susceptible. When these organs are infected, the flower buds stop developing and the diseased parts are covered with a powdery mold layer; the base of the panicle turns brown first, and the entire flowering branch gradually turns brown, causing flower drop. Leaves Symptoms mostly appear first on the underside of the leaves. The powdery mold layer mostly occurs in the midrib area, and the affected leaf tissue shows light gray patches. In severe cases, the damaged leaves become deformed and fall early. Fruit It mainly affects young fruit. In severe cases, the powdery layer often covers the entire fruit surface, and the epidermis of the diseased part turns brown and cracks; affected fruit drops very easily. Although lightly diseased fruit may continue to grow, after the powdery mold layer falls off, the diseased part shows purple patches, cracking and lignification. Pathogen The pathogen of mango powdery mildew is Oidium mangiferae Berther, belonging to the Deuteromycotina. The powdery mold layer growing on the affected organs consists of the mycelium and conidia parasitizing the epidermis. The conidia are oval, single-celled, colorless and produced in chains. No sexual stage has been observed. Disease pattern Mango powdery mildew overwinters as mycelium in infected older leaves and branch tissues. In spring of the following year, when environmental conditions are suitable, the overwintering mycelium produces conidia, which are spread by airflow to cause infection. Temperature is the main factor affecting the occurrence of mango powdery mildew. When the monthly average temperature is 21-22°C, it is most suitable for the occurrence of powdery mildew. Humidity has less influence; when the relative humidity is around 70%, it is favorable for disease occurrence, but under drought conditions the disease also occurs severely. Excessive application of nitrogen fertilizer makes the branch and leaf tissues soft and prone to powdery mildew infection. Varieties such as Zihua mango, Guixiang mango, Qiu mango and Yuexi No. 1 are relatively susceptible.
Prevention and control methods 1. Plant disease-resistant varieties. 2. Apply more organic fertilizer and phosphorus and potassium fertilizer, and control excessive application of chemical nitrogen fertilizer. 3. Chemical control should begin spraying from the early flowering stage, once every 15-20 days. Effective agents include: 20% triadimefon emulsifiable concentrate 3000 times solution; 15% triadimefon wettable powder 3000-4000 times solution; 40% duosulfur suspension concentrate 350-500 times solution; 250-300 mesh sulfur powder, etc. Note that sulfur agents should not be used when the temperature is too high, so as to avoid phytotoxicity.
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