The latest control methods of watermelon gray mold

Botrytis cinerea of watermelon occurs all over the country, which is caused by Botrytis cinerea infection in the subphylum Botrytis cinerea, which occurs seriously in the humid and rainy areas of the south, resulting in dead seedlings, rotten melons and reduced production, except watermelons. It also harms cucumbers, eggplants, tomatoes, beans and other vegetables. Let's take a look at the prevention and control methods of watermelon gray mold.

Harmful symptoms

Botrytis cinerea mainly harms the leaves, stems and fruits of watermelon. The young leaves appear watery stains at first, and then expand into brown or ink spots, which are easy to perforate. There are oval or longitudinally sunken black spots on the stem and cracks in the middle. The young fruit is initially dark brown sunken spot, and the later development is blocked and deformed fruit. Fruit disease spot many sore-like, some cracked or rotten into holes, the disease secreted translucent glue, and then become amber block. When the humidity is high, there is a dense coal color mold layer on the surface of each disease department. Botrytis cinerea can be called a destructive disease of watermelon, the harm is extensive, it is difficult to eradicate, seriously affect the yield and quality, the yield can be reduced by more than 50%, until the end of production.

Morbidity regularity

The pathogen overwintered in the soil with mycelium and sclerotia. In the following spring, the mycelium produced conidia and sclerotia germinated to produce conidia disk, which spread through airflow and Rain Water, harming watermelon seedlings, flowers and young fruits, causing primary infection, and producing mildew layer in the diseased part, further producing a large number of conidia, infecting watermelon again and spreading. When the temperature is low in autumn, sclerotia sneak into the soil to survive the winter. The suitable temperature for the growth of the pathogen was 22: 25 ℃, and the survival temperature was-2: 33 ℃. The relative humidity of the air formed by conidia is 95%. Therefore, under the conditions of high temperature and high humidity, the disease occurred more seriously.

Chemical control

1. Biological agents: you can choose 1% Wuyisin water agent 200 times liquid, spray 2030 kg per mu, spray once every 7 days or so, spray 2 times continuously.

2. Chemical pesticides: at the initial stage of the disease, you can choose 50% carbendazim or isobaric urea wettable powder 1000-1500 times liquid, or 60% Fangmaibao wettable powder 500 times liquid, or 70% thiophanate wettable powder 800 times liquid, spray once every 7 days or so, spray 2 times continuously for 3 times. 40% Huile suspension or 21% chlorothalonil or 20% propiconazole emulsion can also be used, all of which have good control effect.

Agricultural prevention and control

The main results are as follows: 1. Rotation is carried out for more than 3 years, and fully mature organic fertilizer is applied.

2. Seedling soil disinfection per square meter seedling bed or planting hole is irrigated with 1000 times solution of 70% sodium sulfonate.

3. Fumigation shed with chlorothalonil smoke agent or iso-carbamide smoke agent for greenhouse disinfection, 0.25 kg per greenhouse, once every 8-10 days, for 2-3 times.