Control methods of pumpkin powdery mildew

Pumpkin powdery mildew is the most common and serious disease of pumpkin, and pumpkin is also a kind of melon that suffers the most from pumpkin powdery mildew, which mainly harms the leaves. The surfaces of the injured leaves are mostly covered with powdery matter, which obviously hinders photosynthesis. Serious leaves are withered and yellow and even scorched, affecting the fruiting of pumpkins. Let's take a look at the prevention and control methods of pumpkin powdery mildew.

Hazard characteristics

The plant suffering from pumpkin powdery mildew suffered heavily in the late growth period, mainly harming leaves, petioles or stems, and less damage to fruits. Small white mildew spots appeared on leaves or tender stems at the beginning, and then expanded into 1-2 cm mildew spots, which expanded rapidly and connected to each other when the conditions were suitable. White powdery matter covered the whole leaf surface, causing the leaves to wither or curl but did not fall off, and the mildew spots turned gray at the end of autumn, and small black spots grew on them, that is, the pathogen closed capsule.

Disease condition

The incidence of pumpkin powdery mildew reached its peak when the alternation of high temperature, high humidity and high temperature and dryness. at the same time, the disease was easy or serious in the fields where urea and other nitrogen fertilizer were applied too much, too dense and wet, and the pathogen overwintered on the old plant and diseased body after production. There is still a lack of comprehensive investigation on the resistance among varieties. At present, it is only known that the Phoenix pumpkin bred in Taiwan is resistant to powdery mildew. Tanzi pumpkin in Shashi, Hubei, and Jin pumpkin No. 3 in Taigu, Shanxi are also more resistant to powdery mildew.

Prevention and cure method

1. Select improved varieties: at present, Japanese Yixiang pumpkin, Jinchestnut pumpkin and tangerine pumpkin have certain disease resistance, but we should do a good job of purification and rejuvenation and select disease-free seedlings.

2. Seed disinfection: dry the seeds in the sun for 1-2 days before sowing, in order to kill the epidermal bacteria and improve the germination potential. Soak the seeds in 50-55 ℃ warm water for 30 minutes, reduce the temperature to 30 ℃ and continue to soak the seeds for 8-10 hours, then disinfect them with 1% potassium permanganate solution for 20-30 minutes, rinse and accelerate germination under 28-55 ℃ for 48-72 hours, and sow seeds when exposed.

3. Strengthen management: it is best to rotate gramineous crops for 2-3 years, applying 5000-7000 kg of rotten farm manure, 20 kg of ternary compound fertilizer, 15 kg of potassium chloride and 5 kg of urea per mu. During the extension period, there is generally no topdressing, and during the fruit expansion period, 20 kg of potassium sulfate compound fertilizer is applied per mu, and the soil is kept moist, and ditches are cleared and drained in time after rain. Remove the basal disease and old yellow leaves in time, and bury them deeply or burn them centrally. Strengthen the ventilation and light transmission in the field and enhance the stress resistance of the plant.

4. Spray protective film: before or at the initial stage of the onset of pumpkin powdery mildew, 99.1% trichlorfon 300 times 500 times liquid was sprayed on the leaves to form a protective film, sprayed once every 5 to 7 days for 2 times in a row.

5. Chemical control: timely drug control from late April to July. Before the occurrence of the disease, 53.8% can be selected to kill 2000 type 1000 times liquid. At the initial stage of the disease, 1500 times of difenoconazole or 8000 times of flusilazole can be selected, or baking soda can be used to prevent and cure the disease. When individual leaves have 1 or 2 disease spots, spray once every 3 to 4 days, 4 times continuously for 6 times. Baking soda can not only prevent diseases, but also promote growth, and increase pumpkin yield by 1020%. Use small aperture spray plate as far as possible when spraying to reduce the surface humidity of the blade.