Occurrence and control of gray mold in shed
Botrytis cinerea mainly affects leaves, which are divided into white point type, dry point type and wet rot type.
1. White-point and dry-tip types produce white or taupe spots on the front and back of the leaves, which develop downward from the tip of the leaves. Generally, the leaves are more front than the back, and the lesions are prismatic or elliptical. Block, half-leaf or whole leaf withered. The dry tip type is rotted downward from the mouth of the cutting knife. It is initially water-soaked, and then becomes light-colored and has a brown wheel pattern. After spreading, the lesions are mostly semi-circular or "V" shaped and can extend downward by 2 to 3 cm. It is yellowish brown with a grayish-brown or gray-green fluffy mildew on the surface.
2, wet rot type occurs when the humidity is high, the surface of the dead leaves is densely ash to green velvet mold, accompanied by musty smell, no white spots on the leaves. In the storage and transportation of leeks, the diseased leaves are completely wet and rot, and gray mold is produced on the surface.
Law of onset
The gray mold of the leek is mainly spread by the conidia of the pathogen; each time the leek is harvested, the germ can be scattered on the soil surface, and the new leaves are infected by the water flow and the farming operation. The occurrence of the disease is closely related to temperature and humidity. The suitable temperature for mycelial growth is 15-21 °C. The temperature is the main factor inducing gray mold. The relative humidity of air is more than 85%, and the incidence is light or not. In addition, at night, the leeks are frozen, and the temperature is high during the day, while the humidity is high and the incidence is heavy.
Control method
1. Agricultural control
1 After cleaning the shed, the leeks are harvested, and the sick body is removed in time, buried or burned to prevent the spread of germs.
2 ventilation and humidity, timely ventilation and humidity, to prevent excessive humidity in the shed, is the key to prevention and treatment of the disease. According to the weather changes, the shed film is opened and opened at noon for ventilation and dehumidification, so that the relative humidity of the air in the shed is reduced to less than 70%. The amount of ventilation depends on the growth of the leek, and it is strictly forbidden to lower the wind.
3Cultivate strong seedlings to raise and apply more organic fertilizers, timely topdressing, watering, weeding and raising cockroaches to enhance the disease resistance of plants.
The dry straw plants between the four rows of grass and desiccated plants absorb moisture, reduce humidity and maintain ground temperature.
2. Chemical control.
1 Dust method In the early evening of the onset of leek, use a duster to spray 10% of the dust, or 5% chlorothalonil dust, the average amount of 1 kg per 667 square meters, once every 10 days, Use continuously or alternately with other control methods 2 to 3 times.
2 In the early stage of the smoke method, use 10% keeling smoke agent, 200-250 grams per 667 square meters, or 45% chlorothalonil smoke agent, 250 grams per 667 square meters each time, split 6-8 One point, in the evening, lit the canopy fumigation. Once every 10 days, continuously or alternately with other control methods 2 to 3 times.
3 spray method in the early stage of the disease, each time before harvesting the soil must be sprayed, rotating spray 50% carbendazim or 70% thiophanate-methyl WP 500 times solution, if necessary, 50% speed Keling Or 50% of the phlegm-resistant WP 1000-1500 times, alternately used, once every 7 days, continuous control 2 to 3 times.
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