The gray mold of leek, also known as "white spot blotch" and "white spot rot disease", is the main disease of greenhouse leeks, and should be prevented and reduced earlier to increase the benefits.
Occurrence conditions
1. The suitable temperature for the pathogenic bacteria to spread is closely related to the temperature and humidity in the shed. The optimum temperature for the growth of the mycelium is 15 to 21°C, and the sclerotia are produced when the temperature is high. The relative humidity is 85%, and the incidence is severe when the relative humidity is above 95%, and less than 60% is less or not.
2. The gray mold of leeks and the shed environment are related to the shed indoors, hot and cold in the shed, cold at night, during the day, the leeks are frozen by the high temperature, high humidity or bottom wind, the temperature difference between day and night is too large, and the night leaves have water droplets. Resulting in aggravated condition.
3. Diseases related to resistance to disease caused by gray mold of leeks Firstly, the disease resistance of the cultivars is poor; second, the microclimate inside the shed is not effectively controlled, and adverse environment affects the disease resistance of leeks, resulting in morbidity.
4. Insufficient fertilization in vegetable fields related to gray mold and management level of the leek, especially the insufficient application of phosphorus and potassium fertilizers, the weak growth of plants and the reduction of disease resistance; flood irrigation, causing excessive humidity in the soil and greenhouses, causing disease; The cold wind at the bottom of the booth is not timely or directly attacked, which aggravates the occurrence of diseases.
Prevention
1, temperature and humidity control according to the weather changes in the amount of open at noon film, ventilated cooling, dehumidification. Ventilation control through the shed temperature, so that the maximum temperature within the shed does not exceed 25 °C, the maximum temperature of the head knife leek can not exceed 23 °C, the temperature difference between day and night can not be greater than 10 °C, the relative humidity within the shed should be controlled below 75%. Note that aprons should be added at the bottom of the booth and the bottom outlet must not be released.
2. Strengthen management First, select good varieties, select good varieties with strong disease resistance when planting; Second, apply enough base fertilizer; base fertilizer should be mainly full of quality organic manure, and appropriately increase the application amount of phosphorus and potassium fertilizers; Medium and trace element fertilizers; Third, reasonable watering, promotion of micro-pipes, drip irrigation or infiltration, avoid flooding irrigation; Fourth, pay attention to the timely and appropriate amount of ventilation, humidity, temperature, reduce leaf condensation; Fifth, in the growth Spraying 0.3%-0.4% potassium dihydrogen phosphate solution during the period promoted the robust growth of the leeks and enhanced disease resistance.
3. After harvesting the leeches in the greenhouse, the diseased leaves and diseased plants shall be promptly removed, and the diseased plant residues shall be brought out of the shed or burned or buried so as to prevent the spread of germs. Combining post-harvest fertilization with cultivating, loosening the soil, eliminating soil moisture, and preventing cutting and disease.
4. Chemical control In the early stage of disease, medication is used for prevention and treatment. After each harvest, spray precautions must be taken.