Powdery mildew and downy mildew of bitter gourd are mainly distinguished according to their symptoms: powdery powdery mildew forms white powder spots on the front and back of the leaves, and bitter melon downy mildew grows white mold on the back of the leaves or the lesions are restricted by veins. However, in the actual field or in the greenhouse, it is impossible to see such typical symptoms. Sometimes only the pale yellow spots on the front of the leaves are seen, and the mildew layer is rarely seen. Many bitter gourd growers often use powdery mildew as a downy mildew disease to prevent and control, resulting in improper medication. Not only does it not control the disease, but delays the disease prevention and treatment time, causing the disease to worsen. The Chinese pesticide network Xiaobian, the diagnosis and prevention methods of these two diseases are introduced as follows, for your reference: Medium Density Fiberboard,Medium Density Board,Medium Density Fibre Board,Mdf Fiberboard Linyi Fengzhize Trading Co., Ltd. , https://www.fengzhize.com
l, diagnosis of bitter gourd downy mildew:
Bitter gourd downy mildew is a disease caused by the genus Pseudomonas in Cuba (genus Fungi). The temperature range of germ germination is 4-32°C, and the temperature is 15～19°C. It is easy to induce this disease in low temperature and rainy days. It is easy to occur in Guangxi from May to June and from September to October. It usually occurs after continuous rain and rain, poor drainage and soil The incidence is high under high water and dense planting. The bitter melon downy mildew is mainly harmful to the leaves. The initial leaf surface is light yellow spots, which are enlarged later. The lesions are polygonal or irregular by the veins (this is different from powdery mildew), and the color gradually changes from yellow to yellowish brown. In severe cases, the lesions merge into plaques. When the humidity is high, white mildew grows on the back of the leaf, and sometimes white hyphae are seen on the leaf surface. When the weather is dry, the mildew layer is rarely seen, and the disease symptoms in the field are similar to those of the bitter powder. When diagnosing bitter gourd downy mildew, it is mainly identified from the initial diseased leaves.
Bitter gourd powdery mildew:
According to the pesticide network , bitter gourd powdery mildew is caused by melon powdery mildew and melon-like single-shell powdery mildew (both are Ascomycetes). The germination temperature of the pathogen of the pathogen is 10 to 30 ° C, the temperature is 20 to 25 ° C, and high humidity is required. The humidity in the field is large, the temperature is 16~24°C, or the incidence is heavy when the water alternates; the cultivation situation is low, the nitrogen fertilizer is too much or the fertilizer is insufficient, the ventilation is poor, and the growth is too prosperous or weak. Powdery mildew of bitter gourd is mainly harmful to leaves and stems, and is rarely harmful to fruits. Primary near-round powder spots, chlorotic spots appear in severe cases, and some become large or covered with whole leaves (front or back), causing the leaves to turn yellow, eventually causing dryness, causing plant growth and blocking of melons, shortening the growth period. Production is reduced. In the fall, sometimes a lot of black dots grow on the white mold spots, which is different from downy mildew.
2, prevention and control of bitter gourd powdery mildew:
1 Selecting resistant varieties is more resistant to diseases. There are Fengcheng brand big meat No. 1, No. 2 and No. 3 bitter gourd.
2 Choose a field with a higher topography, which is good for drainage, and apply the base fertilizer. Avoid applying nitrogen fertilizer. Spray the 2-3 times of Opul or gene activator to increase the disease resistance of the plant.
3 timely clear the field of diseased bodies in greenhouse cultivation, apply more organic fertilizer, less watering in early spring, more cultivating, increase the temperature of the shed, pay attention to ventilation, reduce air humidity.
4 In the early stage of the prevention and treatment of the disease, 15% of the powdery rust (three wow) WP 1500 times solution, or 45% of the ultrafine sulphur glue suspension 150-300 times solution, 73% of the special speed wow WP 1000-1500 times Liquid, 10% Le disease-free wettable powder 1200-1600 times alternately sprayed.
Technical points: Early prevention, powdery mildew occurs very quickly, so it is necessary to pay attention to the discovery of the central diseased plant and timely use of the drug; spray medicine should be thoughtful, spray the leaf surface back spray together, in order to kill the germ; large water volume Spray, when the bacteria is in contact with water or humidity, it is easy to absorb water and rupture and die; continuous drug use, powdery mildew drug control should continue, fully kill residual mycelium and congregational bun, prevent re-population, generally first Spray once every 4 days after the second spray, and spray 2-3 times continuously.
Prevention and treatment of bitter gourd downy mildew:
1 Reference to powdery mildew control measures.
2 pesticide control in the early stage of the disease, alternating use of 64% anti-virus WP WP 500-600 times solution, or 72.2% Plex water agent 500-700 times solution, 72% gram dew WP 500-700 times solution, 80% Xinwansheng wettable powder 6oo times solution, 58% Raydomil manganese zinc (also known as metalaxyl manganese zinc) wettable powder 500-800 times liquid spray. Spraying should be timely, thoughtful and continuous.
The control measures of bitter gourd powdery mildew and downy mildew are basically the same in agricultural control. In the range of moderate temperature, humidity is the key. The temperature is about 20 °C, and the humidity is more than 80%. Therefore, the management of strong field or greenhouse Work, pay attention to the ventilation and dehumidification between the plants, and have the effect of controlling the occurrence and development of diseases.