Cucumber downy mildew layer, with the development of the disease, cotyledons soon yellow, withered. In the adult stage, the leaves begin to have light green water spots. After expansion, they are limited by the veins. They are polygonal, yellow-green to light brown, and the late lesions converge to form a composite film. The whole leaf is dry and curled up by the leaf margins. When the leaves on the back of the lesion gave birth to gray mold layer, when the whole plant leaves dead. Disease-resistant varieties are small and small, and the layer of back mold is also sparse. The sporangia of the bacteria are colorless, solitary or 2-4 bunches, protruding from the stomata, with 3-5 acute branches at the upper part, a sporangia at the ends of the branches, and sporangia oval or lemon-shaped. The top is milky, unit cell, light brown. The sporangia can germinate and grow out of the germ tube, or the sporangia release the zoospores, become circular resting spores, germinate and invade the host. The oospore is spherical, yellow, with knobs on the surface. Cause and regularity The pathogen of cucumber downy mildew is the flagellin subspecies of Pseudoperonospora cubensis, and the sporangium of the pathogen is transmitted 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 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. 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. Downy mildew disease cycle The bacteria passed winter in the protected area and spread in late spring. It can also spread from the south with the monsoon. In the summer, it can be spread by air currents and rain. In the north, cucumber downy mildew is transmitted from the greenhouse to the greenhouse, then to the spring cucumber in the open season, then spread to the cucumbers in the open soil in the autumn, and finally returned to the greenhouse cucumber. The pathogen is a living parasite fungus, the seed is not borne by bacteria, and the pathogen is mainly transmitted by airflow, invading from the leaf stomata. The occurrence of downy mildew is closely related to the temperature and humidity environment around the plant. The onset temperature is about 16°C, while the epidemic optimum temperature is 20 to 24°C, and the relative humidity is required to be above 85%. The spread of the disease is very fast, and some people call it the "running horse". Once there is a central diseased plant, it only takes 3 to 4 times to expand and infect, and it can cause catastrophe, so the key to combating this disease is It is to find the central diseased area or ward as soon as possible. Prevention technology Prevention of Cucumber Downy Mildew It is recommended to engage in agricultural activities from the following aspects and points of attention: Cucumber downy mildew prevention and treatment should be based on prevention, and the period of prevention should be based on temperature and humidity conditions. Prevention is usually done before rainy days and continuous rain. Methods can be sprayed with protective agents or using fumigants, dust, etc. for prevention. Generally, the amount of mu per hectare is between 3 and 3.75kg, which is divided into 4 to 5 places in the shed. After being lit, the shed is drenched, smoked overnight, and then the next morning ventilation. The smoke is smoked once every 5 to 7 days. Once the downy mildew occurs, the medicament is used for prevention and treatment. The agent is mainly made of water-based agent, which should be uniformly applied during spraying, and the leaves should be evenly sprayed on the back and back. The focus is on the back layer of the diseased leaves, and the upper healthy leaves should be sprayed and protected. In addition, we must pay attention to the selection of disease-resistant seedlings of downy mildew; strengthen cultivation and management, appropriate sparse cultivation, use sorghum cultivation: pour small water, prohibit flood irrigation, and avoid leakage in rainy days. Where conditions permit, drip irrigation can be better controlled. Diseases; After the harvest, the diseased leaves are completely removed, brought to the shed, and properly handled outdoors; conditions are given priority to the use of dust or aerosols for prevention and control. 24% Flavonoids Ginkgo Biloba Extract is a kind of Ginkgo Biloba Leaf Extract, which is the Key Product of our company. The stems and leaves of Ginkgo Biloba Leaf are used as raw materials to extract, concentrate and dry yellow brown powder. improving human immunity,Ginkgo Biloba Extract,Ginkgo Biloba Extract Powder,Quality Ginkgo Biloba Extract,Ginkgo Biloba Extract Plant Shaanxi Kepler Biotech Co.,Ltd , https://www.keplerherb.com
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