Downy mildew disease on melon
08/12/2021
Ph.D. Nguyen Minh Tuyen Currently, melons are grown on a fairly large area in Vietnam, they are plants of high economic value. Melons are being consumed by society in large quantities and often in the form of vegetables and fruits. However, in the production process, farmers often face many diseases. In particular, late blight (somewhere called downy mildew) is one of the most dangerous diseases to melons. Late blight has caused crop failure, increased costs and hindered melon production in many regions. * Symptoms and effects: On the leaves, the disease initially causes the leaves to turn pale and shrivel, then dry out. In humid conditions, where new lesions are lightly covered with a thin layer of white fungus, especially the underside of the leaves, the leaves and adjacent parts of the plant also become black and wet. The disease is easy to spread and the garden of melons are rotten in patches. On the fruit, the lesions are usually oval in shape and in humid conditions the lesions are lightly covered with a layer of white fungus, after which the fruit rots. The disease not only causes fruit rot when melons are still in the field, but also continues to cause damage during transportation and storage after harvest.
* Pathogens and conditions of development: Disease caused by the Phytophthora sp fungus. Conditions of development: - Before planting, The garden must not be cleaned of the remnants of the previous crop.. - The garden has been planted with melons, and plants with the same host continuously, or planted near the garden of tomatoes, potatoes, or some other upland crops such as melons, tomatoes, red peppers... - Planting with infected varieties, planting with high density, fertilizing with excess nitrogen, lacking organic and micro-nutrient fertilizers, so the garden is dense. - Water management is not good, gardening is often wet. - Winter-Spring crop, usually with cool or slightly cold temperatures, high air humidity, little sunshine, a lot of fog at night are optimal conditions for the disease to develop... * Effective prevention measures: - Sanitize and destroy disease remnants in the fields and gardens before planting, especially in the previous crop with plants with the same host as melons, tomatoes, potatoes, red peppers, etc. - Find disease resistant varieties to plant - Plant with appropriate density, avoid planting too thick, easy to cause dense and damp in the garden. - Raise high beds, cover with membranes and water appropriately so that the garden is not wet often. - Balanced fertilizing, with enough organic, supplemented with semimacro and trace elements to help increase the resistance of plants such as foliar fertilizer POLY FEED 15-15-30 at the fruiting-blooming stage. - Rotate with other crops if the garden regularly grows melons, tomatoes, potatoes. - When the weather conditions are cloudy, less sunny, more foggy, humid and cool, it is necessary to prevent it first with the following products: TREPPACH BUL 607SL, or ALPINE 80WG - Should be sprayed twice 5-7 days apart when the disease just appears in the field.
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