In the hot season, the author saw some common diseases of cabbage grown in the open field, such as viral diseases, black rot, soft rot, and physiological diseases caused by improper fertilization, especially after a recent period of rainfall. The prevention and control of pests and diseases in cabbage must be strengthened.
Disease
Soft rot
Cabbage soft rot usually starts from the bulbous stage and appears as a water-soaked spot at the base of the outer leaf or leaf bulb. The outer layer of the plant leaves wilts at noon and recovers sooner or later. After a few days, the outer leaf no longer recovers and the disease department begins to rot. The leaf ball was exposed or the base of the plant gradually rotted into a mud or collapsed, and the tissues of the base of the petiole or rhizomes were gray-brown and soft rot. The whole plant rotted badly, and the diseased part emitted odor, which was different from black rot.
Control methods: Strengthen cultivation and management, avoid wounds on vegetable strains; avoid continuous cropping; implement narrow trench cultivation, pay attention to drainage. Early detection of the diseased plant, uprooting, deep burial, diseased point disinfection with lime. Early pest control. In the early stage of disease, the following agents can be used to stop the spread of the disease: Streptomycin from 2 to 3 million units; or from the antibacterial agent “401†0.5 kg plus 250 to 300 kg of water; or 0.5 kg of enemy powder. In the latter stage, 72% of streptomycin-sulfuric acid-soluble powder 4000-5000 times solution can be used as the agent, or 77% can be used to kill 2,000 times that of wettable powder, or 50% of thiram can be used as 500 times. In the initial stage of the disease, the agent was sprayed alternately 3 to 4 times and sprayed every 7 to 10 days.
Black rot
The outer leaf or the base of the leaf ball first develops, and the diseased part appears water-stained at first, and then it is softened and rotted, resulting in bad odor. There are many main symptoms in the field: stem base decays first, outer leaves wilt, leaf bulbs are exposed, and outer leaf margins are charred, and the top or outer leaves of the heart are completely rotted. When the weather turns dry, the decayed leaves lose water. Papery. High temperature and rain, low-lying terrain, poor drainage, or partial application of nitrogen fertilizers are beneficial to the occurrence and prevalence of the disease.
Its prevention methods are: 1, pest control and disease prevention: early attention to control underground pests and reduce insect damage. 2. Agricultural control: Rational rotation, improvement of irrigation and drainage system, cultivation of deep-groove sorghum, application of formula fertilization, avoidance of applying nitrogenous fertilizer. 3, chemical control: available 72% of agricultural streptomycin sulfate 3500 times, or neophytin 4000 times, or 50% Daisen ammonium water agent 800 to 1000 times. The medicaments are used alternately, combined with spraying and showering, sprayed once every 7 to 10 days, and even applied 3 to 4 times.
Viral disease
Infected at the seedling stage, the leaves have chlorotic near-circular spots with a diameter of 2 to 3 mm, after which the color of the entire leaf becomes lighter or becomes dark green and white. In addition to the shading of the young leaves, the adults were infected with black necrotic spots on the back of the old leaves, and the knotted balls were later and loose. The plant strains were infected and mottled leaves appeared on the leaves with mild necrosis of the veins. Pay attention to the prevention and control of pest transmission virus disease in the early stage. In the initial stage of infection, virus can be sprayed with 20% virus K500 times fluid, or with 1.5% antibiotics for disease, 800 to 1000 times liquid, and 83 boosters 100 times, every 7 to 10 times. Spray once a day, continuous spraying 2 or 3 times, can control or reduce the occurrence of diseases. Physiological diseases: In the early and middle stages of the ball, the leaf margin becomes brown and rot, which is caused by the lack of calcium caused by excess nitrogen fertilizer.
Pests
Diamondback moth
Physical control: Plutella xylostella has phototaxis. In the adult stage, a black light lamp is installed every 10 mu, which can trap and kill a large number of diamondback moths and reduce the source of insects. Biological control: Bacterial insecticides such as Bt can make Plutella xylostella significantly affected. Death; chemical control: There are many agents that can be used at present, including: 25% (or 30%) Diflubenzuron No. 1 (or No. 3) 500 to 1000 times fluid, Huajing No. 1 or 50% diazinone EC 1,500 times Liquid, 5% Sodium Chloride 2000 times solution, 5% stuck solution 2000 times solution. The use should be carried out in the early stage of the occurrence, and should be sprayed on the back of leaves or new leaves, every 5 to 7 days, continuous spray 3 to 5 times.
Spodoptera exigua
Trapping and killing prevention: adult insects have strong phototaxis and can be trapped and killed in the field by frequency-vibration insecticidal lamps; chemical control: 24% SC2000 to 3000 times; 15% SC 2000 to 3000 times; prevention and control should be mastered during larvae incubation and The first-instar larvae were applied during the peak period. The spraying time should be morning and evening. The spraying should be even and thorough, and the leaves of the plant should be fully loaded with drugs. The insects are resistant to insects, so pay attention to rotation or alternation of medications. Noctuids are omnivorous and overeating, and they should be uniformly applied when spraying. Night moths have nocturnal habits, and prevention should be carried out in the evening. In the high temperature and drought season, the control of nightflies should increase the water consumption and use drugs alternately, which will improve the control effect.
Spodoptera litura
Trapping: Frequency-repellent insecticidal lamp, sex pheromone and black light lamp or sweet and sour pot to trap adult insects; Chemical control: Application should be carried out in the evening. Pharmaceutics can use 5% Ruijinte 1500 ~ 2000 times, 10% dilute the suspension 1000 ~ 1500 times, 15% of the 5,000 times the suspension of the suspension, 5% inhibit Tai Tai Bao and 5% stuck 1000 ~ 1500 times spray control.
cabbage caterpillar
Biological control: Bacterial insecticides can be used, such as domestic Bt and insecticide liquid No.6, usually 500 to 800 times the dilution concentration; chemical control: can be used to obtain 2.5% of the EC 2000 times, 5% of the sharp Special suspension 2500 times, etc.; can also be used such as Diflubenzuron No. 1 or No. 3, 20% or 25% of the suspension 500 to 1000 times liquid. However, the effect of these agents is slow, and insects are usually killed when their larvae are changed. Therefore, they should be sprayed earlier.
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