What to Do When Muskmelon Gets Powdery Mildew? Disease Conditions and Control Methods

Muskmelon powdery mildew is one of the important diseases harming melon production; it can reduce the plant's photosynthetic capacity, cause premature aging, and even death, seriously affecting the yield and quality of melons. It occurs severely in both spring and autumn, with a relatively high incidence rate. Below is an introduction to the disease conditions and control methods of muskmelon powdery mildew!

I. Harmful symptoms of muskmelon powdery mildew

Melon powdery mildew can occur throughout the entire growth period of melons, mainly harming the leaves, and in severe cases also harming the petioles and stems. When leaves are affected, small white powder spots first appear on the front and back of the leaves, gradually expanding into white circular powdery patches; multiple lesions connect with each other, covering the leaf surface with white powder. As the disease develops, the color of the powdery patches gradually turns grayish-white, and in the later stage small black dots occasionally appear beneath the powdery layer, and finally the diseased leaves turn yellow, necrose and die.

II. Disease conditions of muskmelon powdery mildew

Melon powdery mildew can occur at 10-25°C. Whether it becomes epidemic depends on humidity and the growth vigor of the host. It can germinate at low humidity, and the germination rate increases markedly at high humidity. Therefore, after rain, when it is dry or there is little rain but field humidity is high, the spread of powdery mildew accelerates. Higher humidity favors spore germination and invasion, while high temperature and dryness favor conidial reproduction and disease expansion. Especially when high temperature and drought alternate with high humidity conditions, and there is a large amount of powdery mildew inoculum and susceptible hosts, the disease becomes epidemic. In the north, this disease mostly occurs or becomes epidemic when the rainy season begins in late spring and early summer, or when early autumn is relatively dry. The functional leaves around the fruit-setting area are most susceptible to the disease; afterward, as more fruits set, disease resistance declines and the disease continuously intensifies.

III. Control methods for muskmelon powdery mildew

1. Agricultural control

After the previous crop is harvested, clear away diseased plant residues in the field to reduce sources of infection, cultivate strong seedlings to improve the plants' disease resistance, apply sufficient farmyard manure, increase the application of phosphorus and potassium fertilizers, prevent excessive vegetative growth and premature aging of the plants, prune and remove side branches in time to ensure good ventilation and light penetration for the plants, water reasonably, and ventilate the greenhouse in time to remove moisture.

2. Biological control

Before the disease occurs or in the early stage of the disease, use Trichoderma harzianum leaf type at 300 million CFU/g, spray at 300 times dilution, once every 7-10 days; when the disease is severe, apply once every 5-7 days. 95% mineral oil, Bacillus subtilis, etc. can also be used.

3. Physical control

Use 27% high-fat film emulsion at 80-100 times dilution, spray it on the leaves in the early stage of the disease so that it forms a thin film on the leaves. This not only prevents pathogens from invading but also creates an oxygen-deficient condition that kills the powdery mildew pathogens. Spray once every 5-6 days, for 2-3 consecutive sprays. A few days before transplanting, close the greenhouse; for every 100 cubic meters, use 250 g of sulfur powder and 500 g of sawdust, mix them evenly and put them into 4-5 small plastic bags, place them at points in the evening, light them, and keep the greenhouse closed for 1 night.

4. Chemical control

Spray 2% Nongkang 120 (pyrimidine nucleoside antibiotic) or 2% Wuyimycin (BO-10) aqueous solution at 200 times dilution, or Gaoke Kongbai (azoxystrobin); spray again after 6-7 days. Before the disease occurs, you can also use 45% chlorothalonil smoke agent, 200-250 g per mu, place it at points in the evening, light it with a smoldering fire, close the greenhouse and fumigate for 1 night, then open the greenhouse the next day for ventilation.

The above is Tuliu.com's introduction to the disease conditions and control methods of muskmelon powdery mildew, for everyone's reference only.