Cucumber downy mildew, commonly known as "running horse" or "dry leaf", can be affected by adult plants at the seedling stage. It mainly damages leaves and stems, and suffers less tendrils and pedicels. At the seedling stage, irregular chlorophyll yellow-brown spots appeared on the surface of the cotyledon, and the diameter of the lesion was 0.2-0.5 cm. When the surface of the lesion was wet, brownish-yellow mildew appeared on the back of the lesion, and the cotyledons became yellow and dry when severe.
The incidence of adult plants, mostly from the front of the greenhouse, the diseased plants first appeared on the opposite side of the middle and lower leaves of water-like, light green spots, the front is not significant, after the lesions gradually expanded, the front exposed, the lesion turned yellow-brown, limited by veins, The lesions are polygonal. Under wet conditions, the back of the lesion appeared purple-brown, or gray-brown sparsely moldy layer. In severe cases, the lesions are lumped together and the leaves are dry.
Cause:
Cucumber downy mildew is caused by the flagella flagellum subsp. pseudopyramidalus fungus, and the sporangia of the pathogen spread by airflow and rainwater. In the greenhouse, people's production activities are the main source of infection for downy mildew. The most suitable temperature for cucumber downy mildew disease is 16-24°C, which is lower than 10°C or higher than 28°C. It is more difficult to attack, lower than 5°C or higher than 30°C, and basically does not cause disease. Appropriate incidence of humidity is 85% or more, especially in the leaves with water film, the most vulnerable to the incidence of infestation. When the humidity is lower than 70%, the spores of the pathogenic bacteria are difficult to germinate and infect, and less than 60%, spores of the pathogen cannot be produced.
Prevention:
1. Separation of nursery and production sites, strict elimination of diseased seedlings when planting. For open cultivation, we must choose land plots with high groundwater and well-drained land. It is also possible to reform farming methods, improve the ecological environment, implement mulch film coverage, reduce evaporation of soil moisture, reduce air humidity, and increase ground temperature.
2. A reasonable rotation should be carried out with cruciferous plants, beans, and solanaceous fruit for a 2-3-year rotation, avoiding crop rotation with melons.
3. After discovering a central diseased area or ward, the diseased leaf should be removed promptly and chemical protection should be quickly performed around it. Available 70% zinc manganese phosphorus 500 times, 72.2% Precike water 800 times, 50% methicone WP 500 times 75% chlorothalonil 700 times, 64% antiviral 400 times, 72% Ke Lu WP 750 times liquid. Spray once every 7-10 days, alternate use of pharmaceuticals, spray a total of 2 -3 times, better control effect.
The incidence of adult plants, mostly from the front of the greenhouse, the diseased plants first appeared on the opposite side of the middle and lower leaves of water-like, light green spots, the front is not significant, after the lesions gradually expanded, the front exposed, the lesion turned yellow-brown, limited by veins, The lesions are polygonal. Under wet conditions, the back of the lesion appeared purple-brown, or gray-brown sparsely moldy layer. In severe cases, the lesions are lumped together and the leaves are dry.
Cause:
Cucumber downy mildew is caused by the flagella flagellum subsp. pseudopyramidalus fungus, and the sporangia of the pathogen spread by airflow and rainwater. In the greenhouse, people's production activities are the main source of infection for downy mildew. The most suitable temperature for cucumber downy mildew disease is 16-24°C, which is lower than 10°C or higher than 28°C. It is more difficult to attack, lower than 5°C or higher than 30°C, and basically does not cause disease. Appropriate incidence of humidity is 85% or more, especially in the leaves with water film, the most vulnerable to the incidence of infestation. When the humidity is lower than 70%, the spores of the pathogenic bacteria are difficult to germinate and infect, and less than 60%, spores of the pathogen cannot be produced.
Prevention:
1. Separation of nursery and production sites, strict elimination of diseased seedlings when planting. For open cultivation, we must choose land plots with high groundwater and well-drained land. It is also possible to reform farming methods, improve the ecological environment, implement mulch film coverage, reduce evaporation of soil moisture, reduce air humidity, and increase ground temperature.
2. A reasonable rotation should be carried out with cruciferous plants, beans, and solanaceous fruit for a 2-3-year rotation, avoiding crop rotation with melons.
3. After discovering a central diseased area or ward, the diseased leaf should be removed promptly and chemical protection should be quickly performed around it. Available 70% zinc manganese phosphorus 500 times, 72.2% Precike water 800 times, 50% methicone WP 500 times 75% chlorothalonil 700 times, 64% antiviral 400 times, 72% Ke Lu WP 750 times liquid. Spray once every 7-10 days, alternate use of pharmaceuticals, spray a total of 2 -3 times, better control effect.
Jiangsu Health Medical Technology Development Co., Ltd. , https://www.medicalhos.com