In recent years, as the cultivation area of ​​tomatoes in greenhouses has continued to expand, the phenomenon of re-embolism has become more and more common, resulting in the growing danger of root-knot nematode disease, which seriously affects the production of tomatoes. According to the author's investigations in Changle and Shouguang in Shandong, root knot nematode disease of tomatoes occurs in open fields and greenhouses. Because the environmental conditions in greenhouses are suitable for the propagation of pathogenic nematodes, the disease occurs throughout the year, and the incidence is more severe than in open fields. Loss of disease is generally 20% -30%, and severe cases are as high as 60% - 70%, or even incomplete. In addition to harming tomatoes, it also harms cucumbers, eggplant, lettuce, beans, celery, cabbage, Chinese cabbage, etc. It has now become one of the major diseases of vegetable roots.
Symptoms occur on the fibrous roots and lateral roots. The larvae suck and excite stimulants in the roots, causing the cells to swell to form root nodules of varying sizes. They are initially milky white, then brown, and cracked on the surface. Impede the absorption of water and nutrients from roots. The symptoms of the affected plants were not obvious in the early stage, but they were slow growing in the middle stage, the leaves had yellow color, the fruits fell off, and the fruits were small and small. In the later stages, the plants were wilted and died.
Prevention and control measures The disease belongs to soil-borne diseases and it is difficult to achieve the intended purpose by a single prevention and control measure. We must implement the principle of "prevention first, comprehensive prevention and control," based on agricultural control, and cooperate with chemical prevention and treatment to receive good results.
(a) agricultural control measures. 1. Reasonably turn down. With 2-3 years of rotation for grasses or onions and garlic crops, there is a good control effect, and the prevention of disease with paddy crop rotation is better. Rotary cropping can greatly reduce the number of pathogenic nematodes in soil. 2. Freeze the soil. After the crop was harvested, the sheds were harvested after the harvest and the sheds were removed before and after the “small snowâ€. After two months of freezing, the pathogens were effectively killed. 3. High temperature stuffy shed. During the leisure period of summer booths, the high temperature in summer is used to dig trenches and ridges on the floor of the greenhouse. The trench is filled with water, covered with plastic film, and the enclosure is closed for about 15 days so that the temperature of 30 cm soil layer reaches 54°C - 55 °C for more than 40 minutes, good control effect. 4. Use disease-free seedlings. When purchasing seedlings from other places, quarantine must be conducted to prevent the introduction of diseased seedlings. This is a key measure to prevent the spread of disease. Nursery should use disease-free soil, use disease-free fertilizer, and cultivate disease-free strong seedlings. 5. Strengthen field management. In combination with site preparation, turning topsoil to less than 30 cm can effectively control nematode damage. Rational fertilization water, enhance plant disease resistance. Timely removal of diseased plant debris and field hosts, centralized burning or deep burial, to prevent the continued transmission of hazards.
(b) Pharmaceutical treatment of soil. 1. Apply pesticides. In the 15 days before the seedling colonization, 1.1% matrine powder 3-5 kg ​​per acre, mix well with fine soil, spread the ground uniformly, and then plough into the soil. Can also be after planting, the 1.1% matrine powder 3-5 kg ​​/ acre, or 5% ray ling granules 2.5 kg / acre, in the middle of planting rows spread into the ditch, and then cover practical. 2. Medication Irrigation. In case of local plant damage during tomato seedling stage, the diseased plants can be watered with 1.8% avermectin EC 1500 times, 50% phoxim EC 1500 times or 90% crystal trichlorfon 1000 times, 20-30% after irrigation. Day, depending on the circumstances, once again pouring agent.
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