Watermelon is prone to Fusarium Wilt during Fruit setting period how to Control Watermelon Fusarium Wilt

The pathogen of watermelon Fusarium wilt is Fusarium oxysporum, which is a fungal soil-borne disease with serious incidence, especially in continuous cropping or continuous rainy weather, watermelon Fusarium wilt is very easy to occur and spreads rapidly in watermelon sitting period, affecting the quality and yield of watermelon.

Watermelon wilt

1. Symptoms: at the initial stage, the watermelon leaves gradually wilted from the old leaves to the front end, especially at noon, and could recover sooner or later. After 3 days, the whole leaves withered and sagged and could not recover, and finally the whole plant withered. The base of the stem of the plant is constricted, and some diseased parts appear brown spots or amber gelatinous material. The diseased root became brown and rotten, the stem base was longitudinally split, the vascular bundles on the longitudinal section of the diseased stem turned brown, and pink mildew appeared on the surface of the diseased part when the humidity was high.

2. The regularity of the disease: the pathogen overwintered mainly in mycelium and chlamydospore or sclerotia in unripe organic fertilizer or soil. The bacteria could survive in the soil for 6 years, and the sclerotia and chlamydospore still had vitality after passing through the digestive tract of livestock. When collecting seeds, chlamydospores can stick to the seeds and sow diseased seeds. After germination, the pathogen invades the watermelon seedlings and becomes the secondary source of infection. The secretion of watermelon root stimulates chlamydospore germination, invades from the root hair tip cells or root wounds, first grows in the cells or parenchyma cells, then enters the vascular bundle, develops in the ducts, secretes Pectinase and cellulase, destroys the cells, blocks the ducts and interferes with metabolism, causing watermelons to wilt and die.

Chlamydospores are resistant to high, low temperature and dry environments and are most suitable for survival in soils or red loam soils with 70% moisture. The incidence degree of Fusarium wilt of watermelon depends on the number of bacteria infected in that year. In production, there are continuous cultivation areas with little sunshine, continuous rainy days, large rainfall, heavy soil viscosity, low topography, poor drainage and extensive management, and the disease is more serious. In addition, excessive nitrogen fertilizer, insufficient phosphorus and potassium fertilizer, application of immature bacteria-carrying organic fertilizer, high calcium content in soil, serious damage to Huangshou melon and underground pests are easy to induce Fusarium wilt.

3. prevention and control measures

3.1, watermelon varieties with disease resistance: such as Jingxin series, Zhejiang honey series, Jinzhong Guanlong, Hei Jinggang, Xinong 8, Julong and so on.

3.2, rotation: rotation with corn, sugarcane, rice and other crops as far as possible, do not repeat crops with melons and fruits for 3 to 5 years.

Seed treatment: soak the seeds with 40% formaldehyde 150x solution for 1h (h), or soak 15~25min with 50-60 ℃ warm water (min) (stir continuously with wooden sticks) to kill the germs on the seed surface.

3.4. Cultivate strong seedlings: use disease-resistant rootstock grafting, seedling bowl to protect roots, cultivate strong seedlings, and try not to damage the root system when transplanting.

3.5. Rational fertilization: control the amount of nitrogen fertilizer, increase the application of phosphorus, potassium and trace elements, and enhance the disease resistance of watermelon.

3.6. chemical control: in the initial stage of fruit setting, spray 10% Shuangxiaoling water agent 200x or 50% carbendazim wettable powder 500x or 70% dimethazone wettable powder 500x solution, 60L (liter) per 667m2 (mu), spray once every 10 days for a total of 2x 3 times, spray in sunny afternoon to prevent burning of plant leaves. The diseased watermelon plant should be pulled out immediately, the disease point and the surrounding plants should be removed immediately, and the root should be irrigated with 25.9% Kangkuling water agent 500 times or 10% Shuangxiaoling water agent 200 times or 75% Zhiweiling wettable powder 800 times. The mixed solution of watermelon per plant was 0.4 × 0.5L.