The symptoms and control measures of potato late blight

Symptoms: The disease can invade leaves, stems and tubers. The leaves were infected. Most of them started from the middle and lower leaves. First, water-stained green-brown spots appeared at the tip or along the edge of the leaves. The surrounding area had a wide gray-green halo. When the humidity was high, the lesion quickly expanded into yellow-brown to dark brown spots. The edges are grayish-green and the boundaries are not obvious. It often produces a circle of sparse white mold at the junction of disease and health, especially after rain or early morning. The air is dry and the lesions turn brown, dry, cracked or curled. Stalks and petioles became infected, forming irregular brown streaks, and in severe cases, the leaves were wilting and curled, eventually causing black rot in the whole plant. Potato squash became infected, and the first light brown spot later became irregular brown to purple-brown lesions. It was slightly sunken and its edges were not obvious. The skin of the diseased potato was pale brown to dark brown, and eventually caused the potato pieces to rot. Incidence conditions and transmission methods: warm and cool nights, humid air, rainy, foggy, average temperature of 10-22 °C, is conducive to disease. The pathogenic bacteria mainly overwinter in mycelium with mycelium. Seeds of fungus were planted, germinated and unearthed to become the central diseased plant, and the diseased department produced sporangia. The sporangia are re-infected by airflow to form the onset center. The pathogenic sporangia can also infiltrate the soil with rain or water infiltration and produce diseased potato, which is the main source of infection in the next season. Control techniques: (1) Use virus-free seed potatoes. The first-grade virus-free seed potatoes of new varieties such as Feirui it, Zhongda No.2, and Yanzhou No.3, which were introduced into the county, can be promoted for planting. (2) Seed processing. Strictly select disease-free seed potatoes as seed potatoes, and use 72.2% Preclosure 600 times liquid or 72% Kelu wettable powder 600 times soak for 10-15 minutes and then dry and plant. (3) Cultivation management. Select land with loose soil and well-drained land; avoid partial nitrogen fertilizer and water accumulation in the fields after rain; find central diseased plants and remove them in time. (4) Chemical control. At the beginning of the disease, 72% Kelu powder 600-800 times solution, or 72.2% Precloxin 600-800 times solution, or 40% Phytonin powder 250 times, or 58% metalaxyl MnZn powder 500 times solution , Or 30% chlorothalonil 500 times spray control.

Speaker & Sound Box

Speaker Box,Sound Box,Bluetooth Speaker

Shenzhen Piofond Technology Co., Ltd. , http://www.szliionbattery.com