Prevention and cure technology of common diseases of watermelon

First, watermelon anthracnose

Symptoms: When the disease occurs in watermelon, the leaves and melons are more seriously damaged. The lesions are nearly round, watery, yellowish brown, slightly sunken, black afterwards, with purple and black halo; the lesions on the fruit are nearly round, pale green, watery, and later dark brown to purple, slightly sunken , can be merged into irregular large spots, and cracks occur.

Control methods: 1 use disease-free seeds, or seed disinfection. After soaking in warm water of 55 ° C for 15 minutes, it was cooled; or soaked with 40% formalin 150 times for 30 minutes, rinsed with water, and then immersed in cold water for 5 hours. It is worth noting that because of the different sensitivity of formalin to watermelon, it should be tested first to avoid phytotoxicity. 2 It is carried out for more than three years with non-melon crops. 3 strengthen management, scientific fertilization. Use fully decomposed organic fertilizer; select sandy soil to level the land, prevent water accumulation, timely drainage after rain; reasonable close planting, timely clear the field weeds. 4 chemical control. In the early stage of the disease, the protective ground and the open field were sprayed with 50% thiophanate-methyl WP and 75% chlorothalonil WP.

Second, watermelon blight

Symptoms: At the beginning of the disease, the leaves of watermelon are gradually wilting from the back to the front, which seems to be lack of water. It is especially obvious at noon, but it can be recovered in the morning or evening. After 3-6 days, the whole leaves will sag and cannot be recovered. The base of the stem is curled up, and some cases have brown spots or amber gel. The root of the disease turns brown and rot, the base of the stem is longitudinally split, and the vascular bundle on the longitudinal section of the diseased stem becomes brown. When the temperature is high, pink mildew appears on the surface.

Control methods: 1 practice more than 7 years of rotation. Watermelon and corn or sugar cane rotation are also advocated, and water and drought rotation can also be implemented. 2 Control the amount of nitrogen fertilizer applied, increase the application of phosphorus, potassium fertilizer and trace elements. 3 seed treatment. Use 50-60 ° C warm water to 50% carbendazim WP 1000 times, soak seeds for 30-40 minutes; or soak seeds with 10% bleach for 10 minutes, then mix with 0.1-0.15% 50% carbendazim WP Kind. 4 seedbed and soil treatment. Use 40% pentachloronitrobenzene or 50% carbendazim WP 1 kg plus 200 kg, mix well with the seed bed nutrient soil and sprinkle it into the seedbed or planting hole. 5 chemical control. At the beginning of the fruit set, use 40% polysulfur suspension, 20% Xiangyan plant disease to prevent and control, spray once every 10 days, a total of 2-3 times.

Third, watermelon disease

Symptoms: This disease is harmful to the leaves, stems and fruits of watermelon. Leaf infection, primary dark green water-stained round or irregular shape lesions, then rapidly spread, when the humidity is high, decay or like boiling water, dry after the light brown, easy to break; stem base disease, raw spindle Water-stained dark green sag, then rapidly spread to the whole fruit, causing the fruit to rot, emitting the smell of silage, the surface of the diseased part is dense white hyphae, and the border of the disease is not obvious.

Control method: 1 seed disinfection. Seeds were soaked in warm water at 55 ° C for 15 minutes, or 150 times with 40% formalin, soaked for 30 minutes, rinsed, and dried for sowing. 2 Agricultural control: Select well-drained fields, plant in high ridges, and drain in time after rain. 3 chemical control: in the early stage of the disease with 70% ethyl phosphine manganese zinc wettable powder or 58% metalaxyl manganese zinc wettable powder control, every 7-10 days, continuous control 3-4 times, if necessary, can also be used The bactericide is irrigated, and the diluted liquid per plant is 0.4-0.5 kg. If spraying and irrigating at the same time, the control effect is obviously improved.

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