Introduction to the causes and control measures of gray mold of leek

Leek is a kind of vegetable with great vitality, and it can grow well even in a harsh environment, so it is also called lazybones. Chinese chives are vulnerable to gray mold in the process of planting. Let's take a look at the causes and control measures of leek.

I. the cause of gray mold of leek

1. Improper selection of varieties. Some leek varieties are more likely to be infected with Botrytis cinerea, so it is necessary to know this knowledge in advance and do a good job in seed selection before planting.

2. the source of bacteria is abundant. Planting leek for a long time, single variety, coupled with farmers' weak awareness of crop rotation, there are many residual Botrytis cinerea in the soil, and the bacteria propagate rapidly, which is one of the reasons for the disease.

3. Improper fertilization. The lack of nitrogen, phosphorus and potassium fertilizer, especially the insufficient amount of phosphorus and potassium fertilizer, reduced the disease resistance of leek.

4. Improper cultivation and management. The occurrence of Botrytis cinerea is closely related to the level of field management. The disease is serious in the fields with low-lying terrain, shallow ditching and poor drainage; the soil is barren or hardened and anoxic, and the plant growth is weak, which is conducive to the occurrence of the disease; the over-densely planted plants, the leaves are prosperous and the nitrogen fertilizer is applied too much, which causes the plants to grow excessively, which is beneficial to the disease; continuous cropping fields, especially those continuous cropping with beans, are seriously affected; in case of ten droughts. Flood irrigation is also adopted, resulting in excessive soil moisture and easy to occur; in case of cooling, it can aggravate the occurrence of the disease.

5. Soften the object to carry bacteria. Due to the long planting time, the softening objects produced by farmers are used many times, and they are used again without disinfection and sterilization, which directly carry bacteria and cause the disease.

Second, the incidence regularity of Botrytis cinerea in Chinese chives.

The disease is caused by the infection of fungal penicillium subphyllium. It mainly harms leek, onion, green onion and other onion and garlic vegetables. The pathogen overwintered in the soil with the disease residue in the form of mycelium or sclerotia, or the conidia overwintered on the surface of the bulb. However, in the warm climate areas, most of the conidia overwintered on the diseased remains. Conidia were produced in the following spring when the conditions were suitable. The conidia are spread by airflow or Rain Water anti-splash, and the bacteria invade the leaves from stomata or wounds, causing primary infection. The conidia produced in the disease department spread and re-infected with airflow, Rain Water and agricultural operations. After 21 months, the survival rate of 15 cm sclerotia buried deep in the soil is still 79%.

The pathogen likes cold and high humid environment, and the optimum climatic condition for the disease is 15-21 ℃, and the relative humidity is more than 80%.

III. Control measures of Botrytis cinerea in leek

The weather is changeable in spring, the temperature rises wavily, accompanied by Rain Water, the humidity is high, the leek is easy to be infected with gray mold, the stems and leaves are covered with gray mildew after decay, softening, lodging, resulting in reduced production and loss of harvest, and spread rapidly, making the whole field sick. Therefore, in spring, we should pay attention to the prevention and control of leek gray mold, in order to protect the stems and leaves.

Usually, we should pay attention to check the stems and leaves of leek and find that there are gray mildew on the stems and leaves. When the stems and leaves soften, lodge and rot, it is necessary to spray 1500 times 50% Curcumol wettable powder aqueous solution or 1000 times 40% isobarbamide wettable powder aqueous solution for prevention and control. Foliar spraying once every 7 to 10 days, continuous spraying 2 times 3 times, evenly spraying all stems and leaves, it is appropriate to start with water droplets dripping.

Encounter continuous rainy weather, humidity, should seize the moment of sunny days to spray the above fungicides to prevent, in order to protect the stems and leaves.

If 0.2%-0.3% potassium phosphite aqueous solution is added to the medicine solution, the control effect is better, which can not only strengthen the efficacy of sterilization and treatment, improve the control effect, but also enhance disease resistance and speed up the recovery of normal growth of diseased stems and leaves. it can also supplement nutrition from leaves, promote strong stems and leaves, increase yield and improve quality.