Control techniques of watermelon diseases and insect pests

Watermelon is an annual vine of the family Cucurbitaceae. The main diseases are watermelon anthracnose, watermelon quenching disease, watermelon virus disease, watermelon powdery mildew, watermelon blight, watermelon cotton rot, watermelon white silk disease, watermelon vine blight, watermelon brown rot, watermelon root knot nematode, watermelon leaf blight and watermelon wilt and so on. Let's take a look at watermelon pest control techniques.

Watermelon anthracnose

[symptoms] at the seedling stage, semicircular or round brown spots appeared at the edge of cotyledons, with black dots or reddish sticky matter. The young stem was damaged, and the diseased part was dark brown and constricted, causing melon seedlings to lodge. Leaf disease spot, in fact, is a round light yellow water stain-like spot, and then turn brown, the edge is purple-brown, the middle light brown, there are concentric wheel patterns and small black spots. Plaques are prone to perforation.

[occurrence regularity] the optimum temperature for the growth of the pathogen was 2425 ℃, the humidity was more than 90%, and the disease was mild under the condition of high temperature and drought.

[control methods] first, disinfect the disease-free seeds or seeds, soak the seeds in 55 ℃ warm water for 15 minutes, or soak the seeds in 40% formaldehyde solution for 30 minutes, rinse with clean water and accelerate germination. At the initial stage of the disease, 70% mancozeb 400 × 500 times, 65% mancozeb or carbendazim 500 times, once in 5 days, 2 times in succession.

Watermelon catchment disease

[symptoms] at the beginning of the disease, the seedlings showed yellow water stains near the ground, then turned yellowish brown and dried up and contracted, and the seedlings were broken as soon as they were pulled out.

[occurrence regularity] germs spread with Rain Water and running water. Low ground temperature (10-15 ℃), high humidity of seedling bed, cool night and lack of light during the day are beneficial to the disease. There are more bacteria in seeds and beds, and there are more chances of seedlings being susceptible to disease.

[control methods] ① agricultural control: strictly select the soil with high topography, good drainage and unplanted melons. Strengthen the management of seedbed and do a good job of heat preservation, ventilation and humidity reduction. When the humidity of the seedbed is too high, a small amount of plant ash or dry soil can be sprinkled and ventilated to reduce humidity. ② chemical control: immediately pull out the diseased seedlings when the diseased plants appear, and spray the copper ammonia mixture to prevent the spread of the disease. It can also be sprayed with 75% chlorothalonil 700 × 800 times.

Watermelon virus disease

[symptoms] the upper leaves of muskmelon plants first showed symptoms, showing dark and light green flowers and leaves mottled, leaves becoming smaller and curly, stems twisted and atrophied, and plants dwarfed. Melons and fruits become smaller, and there are dark and light green mottles on them. Watermelon damage, leaves appear yellow and green spots, uneven leaves, new leaf deformities, infected leaves narrow and long, wrinkled and twisted, floral organ dysplasia, no fruit or fruit deformity.

[occurrence regularity] High temperature and strong sunshine are beneficial to the disease, and the melon fields with lack of fertilizer and weak growth are often serious.

[control methods] to kill aphids in time, the effective agents are 20% butyl emulsion 3000 times, 2.5% deltamethrin 2000 times 3000 times, 40% dimethoate EC 1500 times 2000 times. In severe cases, spray 15 kg of water with 4 sticks of 800000 units of penicillin. Or the foliar effect of spraying 15kg water with 2 antitoxin (20ml) plus 50g zinc sulfate is also significant.

Watermelon powdery mildew

[symptoms] at the beginning of the disease, small round white spots appeared on the leaves, and then expanded into white powder spots, which were connected into pieces, so that the leaves and stems were covered with white powder.

[occurrence regularity] when the humidity in the field was high and the temperature was 16-24 ℃, the disease was serious. Planting watermelons and melons in greenhouses and greenhouses is often due to poor air circulation and high humidity, which is earlier and more serious than that of open field cultivation.

[control methods] pay attention to field hygiene, remove diseased leaves in time and burn them centrally. Strengthen cultivation management, increase the application of phosphorus and potassium fertilizer, and improve plant resistance. The initial stage of the disease can be sprayed with 120 times of agricultural resistance, or 1500 times of 15% rust, or 800 times of 1000 times of 70% methyl topiramate wettable powder.

Watermelon blight

[symptoms] both seedlings and adults can suffer from the disease, harming leaves, stems and fruits. Cotyledons infected with the disease first showed flooding dark green round spots, the center gradually became reddish brown, constricted or withered near the ground, true leaves infected, primary dark green water immersed round or irregular spots, rapid expansion, high humidity, rot or scalded like boiling water, light brown after drying, easy to break, the base of the stem infected, spindle-shaped immersed dark green sunken spots, surrounded the stem and rotted, all died above the affected part. When the fruit is infected, a dark green round water-immersed concave spot is formed, which rapidly extends to the whole fruit, causing the fruit to rot and emit the smell of silage.

[occurrence rule] the temperature limit of onset was 5-37 ℃. The optimum temperature was 20-30 ℃, and the disease occurred rapidly in rainy season, high temperature and humidity, poor drainage, over-dense planting, dense stems and leaves or poor ventilation.

[prevention and treatment methods] at the initial stage of the disease, 50% nail cream copper wettable powder 700 times, 35% ridozole copper wettable powder 800 times, 72.2% Pulic water 800 times, 58% Redomir-manganese zinc (Ruidu zinc) wettable powder.