Chrysanthemum powdery mildew is one of the common diseases in flowers and it is distributed in both southern and northern China. Chrysanthemum powdery mildew causes poor plant growth, dead leaves, or even no flowering, which seriously affects afforestation and beautification effects and flower production; also harms cineraria, calendula, echinacea, gerbera, cosmos, aster, dahlia, Zinnia, rose, rose, impatiens, beautiful cherry, okra, poinsettia, hollyhock, phlox, begonia and wisteria. Symptoms of chrysanthemum powdery mildew at the beginning of the disease, yellow transparent white spots appear on the leaves, mostly in front of leaves, mainly damage the leaves, petioles and young stems and leaves more susceptible to infection. When the temperature and humidity are appropriate, the lesions can rapidly expand and connect into a large area of ​​white powdery spots or gray moldy layers. In severe cases, the diseased leaves become chlorogenic and yellow; leaf and young shoots are curled, deformed, prematurely decayed and withered; stalks are bent, new shoots stop growing, flowers are small and small, plants are dwarfed or inactive, and even die. phenomenon. Pathogens and the occurrence of powdery mildew caused by the pathogen of powdery mildew fungus is Inulina, the sexual segment is Sphaerotheca fuliginea. In southern China, open field cultivation and northern greenhouses can be chronic diseases. The pathogenic bacteria live over the body of the diseased plant or in the soil. The spring and winter are suitable for the spring of the year. The fruit of the ascites begins to crack, and the ascospores are dispersed. The ascospores are spread and spread by airflow and wind and rain, and can be invaded repeatedly. May from May to November can be the disease, from August to October, the incidence of 20 to 25 °C easy to infect the disease. In the humidity, light is weak, poor ventilation and temperature difference between day and night above 10 °C most likely to occur. Severe onset from September to October, mainly in the fall of wet, dew, and fog in the wet environment of multiple infections. When the air is high in humidity, poor ventilation, and insufficient light, it is induced again. When the watering is too much, the plants are too dense or the effects of drought are impaired, and the cultivation and management are not good, and the plant growth is weak, the occurrence is more serious. Control methods 1. Clear garden treatment in the cultivation of attention to cut too dense and yellow leaves, remove the diseased plants, clean up the diseased leaves, concentrated burned or buried, can greatly reduce the source of the pathogen's infection. 2, strengthen the production and management planting not too dense, control of soil moisture, increase ventilation. To avoid excessive application of nitrogen fertilizer, phosphorus and potassium fertilizers should be applied to increase the disease resistance of plant leaves. Watering should pay attention to keep the leaves dry, to prevent water splashing when watering, or temperature and humidity, invade the host, causing re-infection. 3, drug control potting soil or seedbed, soil drug bactericidal, can be used 50% thiophanate-methyl and 50% thiram (1:1) mixture 600-700 times liquid spraying basin soil or seedbed, soil, up to bactericidal effect . In the early stage of disease, agricultural antibiotic 120 or antibacterial B0-10 emulsion 100 times solution, or 50% Garrinone wettable powder or 75% triclomorphin emulsion 1000 times, spraying 1 time every 10 days, and even spraying 3 times Disease control and spread can be controlled. Especially with 25% of the enemy off (propiconazole) EC 20 ml of water plus 100 kg of spray, spray 10 to 15 days 1 time, even spray 2-3 times, the control effect is better. In addition, 70% of thiophanate-methyl WP can be used during the onset of disease, or 5-60% of thiophanate-methyl WP can be added, and 70 kg of water can be added. Mix and spray every 7-10 times. Spray once a day, even spray 2-3 times; also available 15% Trifenin emulsion 1500 times, or 70% thiophanate-methyl wettable powder 800-1000 times, 50% polysulfide suspension 300 times, or 20 % Radix Ning 2000 times liquid or 75% chlorothalonil WP 600 times, 50% TB 1000 times, sprayed every 7-10 days, sprayed 3-4 times, can be used for good prevention and treatment effect.
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