1, leek maggot. Leek maggots are common pests in leek planting. Larvae eat leek bulbs, which leads to yellowing of leaves, death and bulb rot. The insect likes cool and humid environment, and the application of immature farmyard manure may aggravate the occurrence of leek maggots. More use of plant ash can reduce the occurrence of leek maggots.
2. Botrytis cinerea. Commonly known as "white spot" disease, it can infect leaves under suitable temperature and humidity conditions, and white spindle-shaped spots appear on leaves. After the disease develops, the leaves will dry up, there will be gray-green Mucor when it is wet, and the plants will rot and die in severe cases, which has a great impact on the quality and yield of leeks.
3, leek disease. Leek blight mostly started in the middle and lower leaves, and appeared dark green water stains, which gradually spread to most leaves, making the leaves yellow, soft and drooping. When wet, there were sparse white molds, which could also harm pseudostems.
Due to the short harvesting time of leek stubble, the shortest time may be about 20 days, and the safe interval of pesticides is generally 10- 15 days. In order to prevent pesticide residues from exceeding the standard, it is suggested that pesticides should be selected reasonably, and pesticides should not be restricted by isocarbophos and chlorpyrifos.
In addition to the above control methods, field management and reasonable water and fertilizer management (such as avoiding partial application of nitrogen fertilizer and reasonable application of calcium and magnesium fertilizer) should be strengthened to promote the robust growth of plants and improve the disease and pest resistance of leeks.