How to prevent and control eggplant sclerotinia rot? A detailed guide to the latest methods
Eggplant sclerotinia rot is one of the common diseases of eggplant, and is more severe in protected cultivation than in open-field cultivation. Besides damaging eggplant, it also harms tomato, pepper, cucumber, cowpea, broad bean, pea, potato, carrot and many other vegetables. When the disease is severe, it often causes stems and leaves to wither and die, or even the whole plant to die, directly affecting yield. Let us take a look below at the prevention and control methods for eggplant sclerotinia rot!
Symptoms
At the seedling stage, the disease begins at the stem base. The affected part initially appears light brown and water-soaked; when humidity is high, white cottony mycelium grows out, and the tissue becomes soft and rotted with no foul odor. After drying, it turns grayish white, the mycelium gathers into sclerotia, the diseased part constricts, and the eggplant seedling dies. At the adult plant stage, all parts can be affected. It starts first at the base of the main stem or on side branches 5-20 cm above, initially appearing as light brown water-soaked lesions that are slightly sunken and gradually turn grayish white. When humidity is high, white flocculent mycelium also grows out, the cortex rots, and black sclerotia form on the surface of the diseased stem and in the pith. After drying, the pith becomes hollow, the surface of the diseased part readily cracks, and the fibers are exposed like hemp, causing the plant to die. Affected leaves also first appear water-soaked, then become brown round spots, sometimes with concentric rings; white mycelium grows on the diseased area, and after drying the spot surface easily breaks. Affected flower buds and flowers show water-soaked wet rot and eventually drop off. When the fruit stalk is affected, the fruit drops off. When the fruit is affected, water-soaked spots first appear at the end or on the sunny side, then become brown rot and are slightly sunken; white mycelium grows on the spot surface, and later sclerotia form.
Conditions for occurrence
The pathogen prefers a warm and humid environment. The most suitable conditions for disease occurrence are a temperature of 20-25°C and relative humidity above 85%. In Zhejiang and the middle and lower reaches of the Yangtze River, the main peak periods of disease occurrence are from February to June in spring, and the most susceptible growth stage is from the adult plant stage to the middle and late fruiting stage. Fields that are low-lying, poorly drained, planted too densely, have poor ventilation and light penetration in the greenhouse, and have been continuously cropped for many years suffer severe disease, and years with abundant rain in early spring or during the plum rain period also have severe disease.
Prevention and control methods
1. Cultivating eggplant in plastic greenhouses with plastic film mulching can prevent apothecia from emerging from the soil and reduce the source of inoculum.
2. Treat the soil with chemicals: use 4-5 kg of 50% carbendazim wettable powder per mu, mix thoroughly with an appropriate amount of dry soil, spread it on the bed surface, and then rake it into the soil. This can reduce the primary infection source.
3. Pay attention to ventilation to reduce humidity in the greenhouse. During cold waves, pay attention to heating and cold protection to prevent plants from freezing and becoming infected.
4. Remove diseased plants promptly when found and take them outside the greenhouse for destruction.
5. When apothecia first appear in the field or central diseased plants are found, use treatments in rotation or alternately, once every 10-15 days, for 3-4 consecutive applications. In protected cultivation, the smoke method or dust method can also be used; see cucumber sclerotinia rot for specific methods.