Control methods of muskmelon powdery mildew

Melon powdery mildew is one of the important diseases harmful to melon production, which can cause the decrease of plant photosynthetic capacity, premature senescence and even death, seriously affecting the yield and quality of muskmelon. The disease is serious in spring and autumn, and the incidence rate is 30,100%. Generally, the yield can be reduced by 10% to 20%, and when the disease is serious, the yield can be reduced by more than 40%. Let's take a look at the prevention and control methods of melon powdery mildew.

Harmful symptoms

Muskmelon powdery mildew can occur in the whole growth period of muskmelon, which is mainly harmful to leaves and, in severe cases, to petioles and stems. The disease occurred in the leaves, and white powder spots appeared on the front and back of the leaves at the beginning. Gradually expand into a white round powder spot, multiple disease spots are connected to each other, so that the leaf surface is covered with white powder. With the development of the disease, the color of the powder spot gradually changed to grayish white, and black spots occasionally appeared under the powder layer in the later stage. Finally, the diseased leaves were yellow and necrotic.

Disease condition

Melon powdery mildew can occur at 10-25 ℃. Whether it can be prevalent depends on the humidity and the growth of the host. Low humidity could germinate, and the germination rate of high humidity increased obviously. Therefore, dry or less rain after rain, but the field humidity is high, the epidemic speed of powdery mildew is accelerated. Higher humidity is beneficial to spore germination and invasion. High temperature drying is beneficial to conidia reproduction and disease expansion, especially when high temperature, drought and high humidity conditions appear alternately, and there are a large number of powdery mildew sources and susceptible hosts, the disease is prevalent. In the north, the disease mostly occurs in the rainy season at the beginning of spring and summer or when it is drier in early autumn, and the functional leaves around sitting melon are most susceptible to the disease, and then with the increase of sitting melon, the disease resistance decreases and the disease continues to increase.

Prevention and cure method

1. Agricultural control: after harvesting, remove the remains of diseased plants in the field and reduce the source of infection. Cultivate strong seedlings and improve plant disease resistance. Apply sufficient farm manure and increase phosphorus and potassium fertilizer to prevent plant overgrowth and premature senescence. Pruning and branching in time to ensure good ventilation and light transmission of the plant. Reasonable watering, timely opening shed ventilation and dehumidification.

2, biological control: before or at the initial stage of the disease, use 300 million CFU/ of Trichoderma leaf type, 300 times liquid spray, once every 10 days, once every 5 to 7 days when the disease is serious, and 95% mineral oil, Bacillus subtilis and so on.

3. Physical control: spraying 27% high-fat membrane emulsion 80g / 100x on the leaves at the initial stage of the disease to form a film on the leaves, which can not only prevent the invasion of bacteria, but also form anoxic conditions and cause the death of powdery mildew. Spray once every 5 to 6 days, 2 times in a row. A few days before planting, the shed was closed. 250 grams of sulfur powder and 500 grams of sawdust were used for every 100 cubic meters, mixed evenly and packed into 4-5 small plastic bags. The greenhouse was closed for one night after lighting.

4. Chemical control: spray 2% agricultural antibiotic 120 (pyrimidine nucleoside antibiotics) or 2% Wuyisin (BO-10) or high-tech control white (ethoxystrobin), and spray again every 6-7 days. You can also choose 45% chlorothalonil smoke remover before the disease, 200 grams per mu, distributed at different points in the evening, lit by a dark fire, closed the greenhouse for one night, and opened the shed for ventilation the next day.