Artemisia halodendron downy mildew is an important disease in the production of garland chrysanthemum. It mainly damages the leaves and the seedlings suffer. The positive symptoms of the leaves are not obvious. The white frost-like mold layer appears on the back of the leaves, and the seedlings are severely brown. Onset of disease, caused by round or polygonal brown chlorotic spots, leaves gradually yellow, white back layer disease layer of mildew. When the environmental conditions are appropriate, the disease develops rapidly, causing the diseased leaves to die. The suitable temperature for pathogenic infection is 15°C-17°C, which requires 85% relative humidity. There is a large temperature difference between day and night in autumn and a long period of condensation. It is a time when the disease is prone to occur, and it is aggravated when it encounters fog and rainy weather. In addition, continuous cropping, planting too dense, large groups, excessive use of nitrogen fertilizers, poor ventilation and poor light, or poor drainage, will also increase the occurrence of diseases.
Control measures: The planting density should be reasonable, to avoid over-close planting, in order to facilitate ventilation and dampness; reuse basic fertilizer, increase organic fertilizer, control the amount of nitrogen fertilizer to prevent leggy; irrigation to avoid flood irrigation, drainage in time after rain. At the beginning of onset, 40% of aluminum phosphate wettable powder 250 times liquid, 58% of metalaxyl manganese zinc wettable powder 500 times, 64% of antitoxic powder wettable powder 500 times liquid, 72% of Kelu wettable powder 700 times Liquid, 72.2% Precloxone 1000 times, 75% chlorothalonil wettable powder 600 times or 69% ank manganese water dispersible granule 1000 times spray control, spray once every 7-10 days, Continuous control 2-3 times. The chlorothalonil-containing smoke agent planted in the shelter can be smoked at 350 grams per mu.
YT-H008
YT-H008
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