Occurrence and Control of Botrytis cinerea in Greenhouse

In recent years, with the continuous expansion of the cultivation area of ​​leeks in protected areas, the occurrence of grey mold of leeks has gradually increased. So remind farmers to pay attention.

First, the symptoms 1. White point type. On the front and back of the leaves, small spots of white or gray-brown color develop from the tips of the leaves. The lesions are spindle-shaped or elliptical, and they synthesize plaques at the late stage of disease, resulting in half-leaf or whole-leaf char. 2. Dry tip type. Cut from the cut edge of the cutting knife, it was initially immersed in water, then it turned light green and had a brown ring pattern. After the spread of lesions, it was mostly semi-circular or “V” shaped and could extend downwards by 2 to 3 cm. Yellow-brown, grayish-brown or grayish green villous surface. 3. Wet rot type. When the humidity is high, the surface of dead leaves is densely ash to green villous mold, with a musty smell, and white spots do not appear on the leaves.

Second, the incidence conditions

1. Temperature and humidity conditions Low temperature, high humidity, and insufficient light are the main conditions for the occurrence of gray mold. The temperature is between 15°C and 21°C, and the relative humidity of the air is above 85%. Diseases are easy to spread. When the temperature in the shed is high and low for several consecutive days, it can reduce the resistance of the leeks and cause illness.

2. Cultivation conditions A lot of nitrogen fertilizer, phosphorus and potassium fertilizer deficiency, nutritional incoordination of leek fields, easy to disease. Fields with poor field management, weak leeks, and poor disease resistance are also susceptible to disease. Long-term continuous cropping is conducive to the accumulation of pathogenic bacteria and the incidence is serious.

Third, control methods

1. Clean the pastoral. After the leek is harvested, the diseased body is promptly removed, buried or burned to prevent the spread of pathogens.

2 timely ventilation and dehydration is the key to the prevention and treatment of the disease. The amount of ventilation should be determined according to the growth of leeks. When the freshly cut leeks or the outside temperature is low, the ventilation volume should be small or the ventilation should be delayed to prevent the wind from sweeping.

3. Cultivate strong seedlings and pay attention to eel breeding. Application of organic fertilizer, timely fertilizer, watering, weeding, raising good wolfberry, improve plant resistance to disease. Before planting per acre, apply 5,000 to 7,000 kilograms of decomposed farmyard fertilizer, 15 kilograms of diammonium phosphate, and 50 kilograms of plant ash. Deeply plunge into the soil and irrigate the floodwater. Apply water promptly after planting. Before the frost top dressing twice, each time after topdressing 15 kg of urea per acre, timely irrigation after top dressing.

4. Spray 5% procymidone or 5% iprodione dust agent 1 kg per mu in the early stage of disease. In addition, it can also spray 65% ​​Methotrexate WP 1000 times or 40% pyrimethanil suspension 1200 times, spray every 10 days or so, even spray 2 or 3 times.

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