Garlic farmers are most worried about the reduction of garlic production, and garlic leaf blight will cause large pieces of garlic leaves to die, light garlic and small, low quality; heavy can not pump out, affecting production, and even harvest, seriously restricting the development of garlic. This article gives a detailed introduction to the symptoms, pathogenesis and prevention methods of garlic leaf blight.
1, garlic leaf blight symptoms
The disease is mainly harmful to the leaves. After the leaves are infected, the initial white flowers appear small dots, and start from the tip of the leaves. After the lesion is enlarged, it has an irregular shape, grayish white, and black mold occurs on the lesion when it is wet, and it changes from grayish white to taupe. The lesions start from the tip of the leaf and expand from the top to the bottom. When it is light, it is dry and dry. In severe cases, the whole leaf or even the whole plant is dead. The peduncle is easily broken from the diseased part, and finally many small black spots are scattered in the diseased part.
2, the incidence of garlic leaf blight
2.1 Soil and fertilizer
Soil is a prerequisite for the severity of the disease. The disease is overwinter in the soil with mycelium or ascospores with diseased bodies. The soil moisture in winter is moderate, the pathogens are easy to survive, and the next year is heavy; the soil is too dry and too wet, which is not conducive to the wintering of the bacteria, and the incidence is light in the following year. The soil is fertile, the diseased body is high, the organic matter content is high, the pathogen is easy to survive; the soil nutrient is low, and the organic matter content is small, which is not conducive to the onset. Excessive application of nitrogen fertilizer, green leaves growth, or insufficient potassium fertilizer, easy to develop.
2.2 host plant
In addition to harming garlic, the pathogen is still seriously harmful to onions in the local area, second only to garlic, but also to lettuce.
2.3 temperature
The disease mostly occurs in the spring. When the average temperature reaches 12 °C after the spring, the disease begins to occur. At 18 °C, the lesions appear in large numbers. The optimal temperature is 15-25 °C, and the temperature is below 8 °C and 34 °C.
2.4 Garlic varieties
The disease resistance of each garlic variety is quite different, and the local varieties planted for many years have a serious incidence.
2.5 cultivation management
The management of fine fields is light, and the use of chemical weeding fields is also mild; the weeds are overgrown and the extensive management of the fields is severe. The roadside fields and the ditch side fields are seriously affected. The pathogen is a weak parasitic strain, and if other diseases occur seriously, or the pests occur seriously, the disease also occurs.
3, garlic leaf blight prevention and control methods
3.1 clean garden
After the garlic is harvested, the diseased leaves and diseased stems in the field are removed in time. Before the ploughing soil, the straw is covered on the soil surface, the straw is burned, the pathogens in the sick body are burned, and the number of bacteria in the field is reduced. , thereby reducing the chance of pathogen infection.
3.2 Strengthening field management
Field management is an important method to prevent and treat the disease. Before the garlic is planted, the garlic seed coat should be peeled off, and the seed coat and stems should be taken out of the field to reduce the infestation conditions. The cultivated land should be high, no water, and cultivated in separate compartments. The width of the car is 1.5-2m. The cart surface is turtle-shaped, and the trough should be straight to facilitate drainage. Reasonable planting density, cultivated in rows, is conducive to ventilation. Remove weeds in the field in time to enhance ventilation and light transmission. Drain in time after the rain. Applying the base fertilizer, nitrogen, phosphorus and potassium should be used together, adding potassium fertilizer, applying organic active fertilizer or seaweed fertilizer to improve the disease resistance of garlic.
3.3 Chemical control
After the diseased plants were found in the field, timely spraying and prevention. Control method: 1 Optional 75% chlorothalonil WP 500 times solution or 50% carbendazim WP 1000-1500 times solution, 12% green milk copper emulsifiable solution 600 times solution 2-3 times, after the drug The relative control effects of 15d were 87.2%, 81.6%, and 77.1%, respectively. However, systemic fungicides (such as chlorothalonil) are more effective than protective fungicides (such as green lactating copper). 2 In the flower bud differentiation period of garlic buds and the elongation period of garlic stalks, start spraying 50% prochloraz WP 1000 times or 10% Shigao water granules 1500 times, 50% carbendazim sulfonate (lysozyme) WP 700 times liquid, 78% wave Mn Zn wettable powder 600 times liquid, sprayed on a good liquid 900kg/hm2, sprayed once every 7-10d, continuous control 3-4 times, can ensure the smoothness of garlic The convulsions and bulbs are normally inflated.
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