Temperature and humidity affect the occurrence of anthracnose how to control watermelon anthracnose

The cause of watermelon anthracnose is closely related to temperature and humidity. The most suitable temperature is 22-27 ℃, below 10 ℃, above 30 ℃. At the appropriate temperature, the higher the humidity, the more serious the disease. When the relative humidity is 85-95%, the incubation period of watermelon anthracnose is only 3 days. The lower the humidity, the longer the incubation period. When the humidity falls below 54%, the disease will not occur.

Watermelon anthracnose

Anthrax symptoms: mainly harms watermelon leaves, but also harms stems, petioles and fruits. The whole growth period of watermelon can occur, but it is more serious during and after growth, resulting in dead leaves and fruit rot. When the disease occurred in the seedling stage, the semi-oval brown disease spot appeared on the edge of watermelon cotyledons, which spread to the young stem and the seedlings were quenched. At the adult stage of watermelon, the leaves are water-immersed disease spots at the beginning, soon dry, dark brown, with yellowish brown halos on the periphery, sometimes with wheel lines, irregular in the later stage, disease spots are easy to break when dry, reddish spots grow on the back of leaves when it is wet, and then turn black. The diseased spot on the stem is spindle-shaped, sunken, discolored in the middle. Fruit damage, the initial appearance of water-immersed dark green spots, enlarged in a round or oval, dark brown, sunken, cracked, wet in the middle of the disease spots produce pink sticky matter, serious watermelons produce a large number of disease spots, is subcutaneous pulp dry rot, and cause rotten melons.

The period of prevention and control is from late May to early August.

Prevention and control methods: give priority to agricultural prevention and control, reduce the use of drugs and reduce pesticide residues.

First, agricultural measures. More than 3 years of rotation and non-melon crops: select disease-resistant varieties, do a good job of seed disinfection, cultivate disease-free and strong seedlings; reasonable formula fertilization, increase the application of organic fertilizer and potassium fertilizer, reduce the amount of nitrogen fertilizer, must use fully mature organic fertilizer, bacteria-carrying fertilizer forbidden; use plastic film mulching and scientific pruning to prevent excessive density and avoid flood irrigation; diseased fruits and leaves should be removed in time, taken out of the field, deeply buried or burned Pay attention to timely drainage in the rainy season, watermelon bedding grass to avoid direct contact with the ground; plant growth regulators or foliar fertilizer can be properly sprayed to enhance the disease resistance of watermelon plants.

Second, chemical prevention and control. In the early stage of watermelon anthracnose, spray control with 1500 times of 10% difenoconazole water dispersible granules, 1000 times of 50% imipramine manganese salt wettable powder, 1000 times of methylthiophanate wettable powder, 50% carbendazim wettable powder, 80% gangrenous magnesium wettable powder, 80% mancozeb wettable powder or 2% Nongkang 120 water, spray once in 7-10 days. Spray 3-4 times in a row.