Prevention and Control of Tomato virus Disease on the Edge of dwarf leaves

Tomato is prone to virus disease in spring, the quality is declining, and the benefit is affected. In order to reduce diseases, reduce the base number of pests, and reduce the probability of pest transmission. The editor reminds you how to recognize and control tomato virus disease in time:

Tomato virus disease

First of all, introduce the cause of viral disease. From an objective point of view, it may be due to the large number of aphids, whitefly and other pests in spring, some virus diseases on overwintering plants are transmitted to tomatoes, resulting in tomato disease. At the same time, adverse environments such as high temperature, strong light and drought also increased the risk of tomato infection to a certain extent. From a subjective point of view, it may be because some tomatoes are weak, have poor resistance, do not have good "physical quality", and have no "fighting back" in the face of virus attacks, so they fall ill.

Secondly, the types and symptoms of viral diseases. ⑴ curved leaf type: after the disease, the upper leaf yellowing becomes smaller, the leaf edge curls up, the leaf shrinks, thickens and curls; the upper node is difficult to bloom, or there is no inflorescence; the growth of infected tomato plants is slow or stagnant, obviously dwarfed. ⑵ mosaic type: after the disease, the leaves appear yellow-green or dark green, light green mottled, sometimes the leaf veins are transparent, serious, the leaves are narrow or twisted, resulting in flower drop, fruit drop, fruit small, plant dwarfing. ⑶ stripe pattern: it can occur on stems, leaves and fruits, with tea-brown spots or moire on the leaves and black-brown patches on the stems. Fruit mask dark brown sunken patches. In severe cases, the plant atrophied and yellowed, and finally withered, even no harvest. ⑷ fern leaf type: the top leaf is particularly narrow or spirally curled, and becomes fern leaf-like from top to bottom, sometimes almost without mesophyll; the petals are enlarged, forming a "giant flower", and the fruit core is brown; the plant is dwarf in varying degrees.

Finally, the prevention and control methods are introduced. ① seed treatment. In view of the main local sources of poison, disease-resistant tomato varieties are selected according to local conditions; seeds are disinfected, that is, before sowing, the seeds are soaked in clear water for 3 hours, then soaked in 10% trisodium phosphate solution for 20 minutes, and then rinsed with clean water. ② avoids aphid and controls aphid. Intercropping of tomato and precocious corn, tomato ∶ corn is 4 ∶ 1, which can be covered with silver gray film instead of plastic film, or two silver gray film strips of wide 10cm can be pulled parallel to the vegetable border above the seedlings after erection; the protective ground can be covered with net yarn to reduce aphids entering the greenhouse; aphid control can be sprayed with pyramids, pyramites, bifenthrin and so on. ③ controls Bemisia Tabaci. The key to control leaf curl virus disease is to prevent Bemisia Tabaci in the early stage of tomato growth, in which seedling stage and about 1 month after transplanting is the key period for control. In the seedling stage, 40-60 mesh insect control net was used as a protective shed to prevent the entry of Bemisia Tabaci, and sprayed with thiazide, bifenthrin, imidacloprid and so on. One or two days before transplanting, the roots were irrigated with thiazine, the solution of each seedling was about 15ml, and the period of validity was 20ml for 30 days. After transplanting, the ventilation of the greenhouse is closed with an anti-insect net of more than 40 meshes, and the yellow board is hung in the greenhouse. For example, the number of Bemisia Tabaci on the yellow board increases, and chemical agents are used to control it immediately. ④ strengthens field management. Crop rotation for more than two years, deep ploughing of soil, application of lime, timely sowing, strengthening management, promoting early seedling development, cultivating strong seedlings, adopting formula fertilization, spraying compound nitrophenol sodium solution 6000 times, etc., to enhance the host's disease resistance, spraying 100 times of NS-83 at 15 days before planting, 2 days and 14 days after planting can not only induce disease resistance of tomato, but also increase yield. The diseased seedlings should be pulled out in time, and the diseased and healthy plants should be operated separately when pruning and branching in the field. ⑤ biological agent prevention and treatment. Before tomato seedlings are divided, planted, strapped and branched, 1% soapy water + 0.2% potassium dihydrogen phosphate, or 1% 20% soybean milk or soy milk powder are sprayed to prevent contact infection. ⑥ was inoculated with attenuated virus strain. When greenhouse tomato seedlings had two leaves and one heart, the attenuated virus strain N14 was sprayed with high pressure spray gun. After inoculation, the temperature of seedling bed was increased and aphid was prevented in time, which could enhance the immunity of tomato to tobacco mosaic virus. Chemical control of ⑦. In the early stage of the disease, Beinong Huada zinc sugar powder can be sprayed with 10 grams of zinc sugar powder mixed with 15 kg water (1500 times dilution) in each bag (1500 times dilution). The effect is better by using the above viral drugs such as zinc sugar powder + dextran (or morphine) and imidacloprid (or Aktai, thiazinone, etc.) to prevent and cure the virus.