What pest control techniques should Chinese cabbage master in early spring?

Accelerate the adjustment of planting structure, popularize efficient multiple cropping techniques such as pepper interplanting with Chinese cabbage in winter and spring and waxy corn interplanting with Chinese cabbage in spring, increase the income of vegetables in one season, increase the economic income of farmers in our county, and promote poverty alleviation without affecting the original vegetable output and output value. In order to ensure the stable production and income increase of Chinese cabbage, pest control is very important.

Luodian County is located in the south of Guizhou Province, with early spring, long summer, late autumn and short winter. Annual average temperature 19℃, annual average rainfall1150 ~1300mm, annual sunshine hours1518h. It belongs to a typical subtropical monsoon humid climate and enjoys the reputation of "natural greenhouse", which provides superior climatic conditions for the development of vegetable planting. Under the care and guidance of vegetable experts from provinces and states headed by Mr. Li Guilian, after 38 years of development, vegetable industry in our county has become a pillar industry to promote rural economic development in Luodian and help poor farmers get rid of poverty and become rich. In order to speed up the adjustment of planting structure, under the guidance of Mr. Li Guilian, after years of experiments and demonstrations, our county has popularized efficient multiple cropping techniques such as pepper interplanting with Chinese cabbage and waxy corn interplanting with Chinese cabbage in winter and spring in Kechun. Without affecting the original vegetable yield and output value, increase the vegetable income in one season, increase the economic income of farmers in our county, and promote poverty alleviation. In order to ensure the stable production and income increase of Chinese cabbage, it is very important to do a good job in crop rotation and pest control. The main pests and diseases of Chinese cabbage are virus disease, soft rot of Chinese cabbage, downy mildew, cabbage caterpillar and so on.

First, spring and summer Chinese cabbage management

1. Pre-broadcast management. First of all, we should do a good job in seed selection and choose high-quality varieties with disease resistance, insect resistance and bolting resistance. Secondly, the choice of land is also very important, and it is necessary to avoid continuous cropping or continuous cropping with cruciferous vegetables, mainly the diseases of cruciferous vegetables have a great influence on the diseases of Chinese cabbage. In addition, the land should be intensively cultivated (generally up to 25 cm deep), weeding and pest control should be done well, and weeds in the field should be intensively cultivated to avoid weeds attaching too many germs and reduce the source of a clean-up. Finally, we should manage fertilizer and water according to crop demand. High-compartment cultivation is beneficial to drainage, effective prevention and control of pests and diseases, and fertility reaches the roots.

2. Do a good job in field management and actively prevent and control pests and diseases. Sowing and planting should be timely. At the seedling stage of Chinese cabbage, attention should be paid to preventing and controlling sudden lodging and ensuring the hardening of ridge soil, which is not conducive to root growth. In addition, we should pay attention to supplement urea and other fertilizers needed for plant growth to enhance plant disease resistance. Canopy stage is the first high incidence period of downy mildew, so special attention should be paid to prevention and control. Entering the core-covering period is the high incidence period of various diseases and insect pests, and soft rot, aphid, black spot, cabbage caterpillar and burning heart disease are the key points of prevention and control. Spray pesticides 2-3 times before closing the ridge in autumn and winter to ensure that the drugs cover the front, back and roots of the leaves. When checking the ridge of the field, once the diseased plants are found, they will be directly uprooted and taken out of the field for treatment to prevent the germs from staying in the field.

Second, the specific points of pest control

1. Downy mildew

(1) occurrence environment. Low temperature and rainy, high and low temperature, large temperature difference between day and night, large dew, prone to downy mildew. Early sowing, poor ventilation, continuous cropping, insufficient basal fertilizer, lack of fertilizer in the core-covering period, late emergence, high seedling density, serious virus disease and slow growth are all conducive to the occurrence and prevalence of downy mildew. Downy mildew can occur in both seedling stage and adult stage of Chinese cabbage, especially in adult stage.

(2) symptoms. The main symptom of downy mildew is brown spots or pits on cotyledons at seedling stage, and white mildew layer appears on cotyledons and stems when wet. In the true leaf stage, polygonal yellow spots appeared on the front of the true leaf, and white mildew layer appeared on the back of the wet leaf. When there are many lesions, interconnection can lead to large-scale death of leaves. The diseased leaves grow from the outside to the inside, which will cause the plant to lose confidence in severe cases.

(3) Prevention and control strategies. After downy mildew appeared in the field, it is suggested to spray 64% disinfected alum 500 times, 70% mancozeb 500 times, 25% thiamethoxam 1000 times and 72% mycophenolate mofetil/kloc-0 times alternately every week.

2. Soft rot

(1) symptoms. In the early stage of soft rot, wilting mainly occurs outside the diseased plants. This wilting state only appears at high temperature at noon and can be recovered sooner or later. In the middle and late stages of the disease, it is impossible to recover sooner or later The soft rot pathogen mainly invades from the root wound of Chinese cabbage. The diseases in Suizhou are getting more and more serious, forming a water invasion area, becoming grayish brown and sticky, and finally causing root rot, top rot and even whole plant rot of Chinese cabbage.

(2) Prevention and control strategies. The pathogen of soft rot mainly comes from soil and can survive for more than 40 months. Bacteria usually invade from the wound at the base of Chinese cabbage (insect injury and mechanical injury). Pathogens are mainly transmitted by rain and insects. In particular, the spread of ground maggots is extremely harmful. On the one hand, pests will bring wounds to the base of Chinese cabbage, on the other hand, pests will also carry soft rot germs. Therefore, drainage and dredging should be done well in the field, and the prevention and control of ground maggots and harmful insects should be done well at the same time.

3. Viral diseases

Viral diseases mainly occur at seedling stage (6-leaf stage). When the seedling leaves grow to 7-8 pieces, it is easy to happen in continuous high temperature weather. The disease spreads quickly.

(1) symptoms. After virus disease, the leaves of plants are twisted, shrunk and shortened, and necrotic spots appear on the leaves.

(2) Prevention and control strategies. Once the scattered seedlings become distorted and short, phosphorus and potassium fertilizers should be supplemented in time to improve the disease resistance of seedlings, and attention should be paid to drought-resistant watering in the field. Generally, 1.5% zhibiling EC 1000 times, 10% imidacloprid 2000 times or 50% pirimicarb are used to control aphids, once a week/kloc-0 times, three times in a row.

4. Pest control

(1) Pieris rapae. Pieris rapae belongs to Lepidoptera and Pieridae. It is dark green with a bunch of small black warts on its back and fine hairs on its surface. Adult Pieris rapae can grow to 3.5 cm, which is extremely harmful. Pieris rapae can bite through the leaves, or eat into the gap at the edge of the leaves, leaving only vegetables. If the cabbage caterpillar is well controlled at the end of packaging, it will be packaged into cabbage balls, resulting in the whole cabbage being discarded.

(2) cabbage moth. Vegetable borer belongs to Lepidoptera borer, commonly known as borer, which harms Chinese cabbage and cabbage. Larvae attach to the heart leaves and leaves of seedlings, and the seedlings stop growing or wither because of the destruction of growth points, resulting in lack of seedlings and broken ridges. Chinese cabbage is damaged, which can't cover its heart and spread soft rot, resulting in reduced production.

(3) Plutella xylostella. Plutella xylostella, commonly known as "rise of the legend", belongs to LEPIDOPTERA Plutella. Light green, generally 1- 1.2 cm long, with fine hairs on the surface. It mainly eats mesophyll on the back of leaves, making them transparent. The big larvae will eat the leaves into the hole.

The above three pests are the most common pests in Chinese cabbage. To do a good job in pest control, we must first do a good job in field management, clean up weeds in the field in time, and minimize the eggs that may be carried in the field. Chemical control can be carried out by alternately spraying 10% imidacloprid wettable powder 1500 times solution, 1.8% avermectin EC 4000 times solution and 5.7% cypermethrin EC. If there is no improvement after repeated spraying, it may be that pests have produced antibodies to pesticides. Therefore, 50% phoxim EC 1000 times solution and 2.5% deltamethrin EC 2000 times solution were sprayed respectively for control.