Powdery mildew is a common disease on the chrysanthemum. It occurs widely in various growing areas throughout the country and seriously affects the yield and quality of chrysanthemum.
At the beginning of the symptoms, small yellow spots appeared on the leaves and gradually expanded. The diseased leaves were covered with white powdery mildew, which is the mycelia and conidia of the pathogenic bacteria. Severe diseased leaves distorted or shed yellow, diseased plants were stunted and dwarfed.
Pathogen Erysiphe cichoracearum DC. The powdered apricot fungus belongs to Ascomycota spp. Mycelium is born on both sides of the leaf, conidia are nearly columnar to barrel-shaped, string-like. Closed capsular flat spherical, multifilament attached, dark brown, size 90-130μm, including ascospores 10-20; ascospores ovate, oblong to elliptic, size 20-2814-18 (μm), asccus 2 ascospores, individual 3; oval, size 19-3811-22 (μm). In southern China, there is generally no behavioral state. Oidium chrysanthemi Rabenh is the non-sexual state.
The pathogenic characteristics of the northern bacteria were as follows: the amenorrhea was left over on the surface of the soil with the amputation of the amenorrhea over the winter, and ascospores were shed for the initial infection the following year. After the onset of the disease, the mycelia of the diseased section were again contaminated and reinfested. In southern or northern greenhouses, the pathogens use mycelium to overwinter on the host. When the conditions are appropriate, the conidial spores are transmitted through the air flow. Sometimes the spore germination invades the invading skin of the host epidermis and absorbs nutrients in the epidermal cells. . The mycelium Dordian sentence grows on the surface of the host, with attachments in many places, forming a closed capsula in late autumn or wintering on the host with mycelium. Cold in spring and autumn, the humidity is easy to disease.
Control methods
1, the agricultural control field should not be planted too dense, pay attention to ventilation and light; scientific fertilizer management, increase phosphorus and potassium fertilizer, timely irrigation, improve plant resistance to disease; defoliation and disease in winter to clear the debris buried deep or burned.
2ã€Initial spraying of 36% thiophanate-methyl suspension agent 500 times or 60% anti-mildew treasure 2 water-soluble powder 800 times, 40% danning agent 600-700 times, 47% Garrinong WP 700-800 times, 20% triadimefon EC 1500 times, every 7-10 days, continuous control 2-3 times. Severe disease can use 25% of the enemy's demulsification oil 4000 times, 40% of Fuxing Star EC 9000 times.
Commonly used drugs thiophanate-methyl, anti-mildew, Dakkonen, Garrinone, triadimefon, enemy force, Fuxing