The occurrence and control methods of vegetable root knot nematodes in Ningxia district
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Root knot nematodes have occurred in greenhouse vegetables in the northern and southern mountainous regions of Ningxia in the past two years. In 2005, the occurrence of heavy cucumbers in spring cucumbers in four stations and Wuzhan Village, Longhu District, Shizuishan City, occurred severely in this year's tomato in some autumn and winter pods. The incidence rate was 100%, and the mortality rate was 11.5%. The root-knot nematodes were found on a cucumber in a solar greenhouse on June 25 this year in Yuanzhou District, and the disease rate was 55% on July 11 and seriously affected the production of greenhouse vegetables. . Judging from the current situation, vegetable root-knot nematodes have gradually spread and aggravate. Therefore, all localities must strengthen monitoring and investigation, and timely guide farmer households to prevent and control losses.
Second, the symptoms of vegetable root knot nematodes mainly harm cucumber, zucchini, tomatoes, eggplant, etc., with cucumber, tomato, the most serious. The root knot nematodes of cucumber and tomato are all (Meloidogyne incognita Chitwood), which is called southern root-knot nematode and belongs to a plant parasitic nematode. Root-knot nematodes damage the fibrous roots and lateral roots of crop roots, forming spherical or conical bead-like knobs of varying sizes, also known as root knots. The roots of tomato often form a string of beetles like millet or mung bean on the root, whereas cucumber root knots form root nodules or roots of varying sizes on the lateral roots. Cut open nodules visible inside the transparent white needle size particles, that is, female adults. The growth and development of the above-ground parts of the diseased plants were hindered, and the symptoms of the light were not obvious. The severe growth was slow, the leaves were yellow, the plants were short and stunted, and the fruits were small and small. As the disease progresses, the plants gradually die.
Third, transmission routes and disease conditions Root-knot nematodes live in the soil 5-30cm, often with 2nd instar larvae or eggs left over with the disease remains in the soil winter, suitable conditions for the following year, overwintering eggs hatch as larvae, continue to develop and Invade the host. The primary sources of infestation were mainly diseased soil, diseased seedlings, and irrigation water. The movement and spread of nematodes over long distances is usually through the use of flowing water, wind, soil relocation, and sick and sick soil, sick seeds and other nutritive materials, as well as human activities. The root-knot nematode lived at an optimum temperature of 25–30°C. It was rarely active above 40°C or below 5°C and was lethal at 55°C for 10 minutes. Soil moisture in the field is an important condition affecting hatching and reproduction. The rainy season is conducive to the hatching and infestation of nematodes, but its activity is inhibited in dry or too wet soils. Suitable conditions for soil pH 4--8, dry terrain, loose soil texture and low salinity are suitable for nematode activity, which is favorable for disease incidence. Sandy soils are often heavier than clays, and disease incidence is heavy in continuous cropping.
Fourth, control methods 1. Thoroughly remove the root cause and focus on it. Regardless of greenhouses or vegetable fields, after the harvest is completed, the sick bodies in the soil should be cleaned immediately to reduce the disease and reduce the incidence.
2. Reasonable rotation. Turning crops can significantly reduce the number of nematodes in the soil and is an easy preventive measure. Such as onions, garlic rotation, can play a role in reducing the source of insects.
3. Extermination at high temperature. Utilize summer high temperature leisure season, Mushi ammonium bicarbonate 500 kilograms, deep ridge irrigation mulching white mulch, keep for 40 days (if you do not expose the greenhouse film, keep 20 days), can effectively kill the insect parasite nematodes.
4. Soilless nursery or seed bed disinfection. Bed soil with new soil not planted vegetables or with 1.8% avermectin 1.5 ml per square meter, dilute 2000 times evenly spread bed soil, mix well and then nurse the seedlings with nutrition.
5. Soil treatment before planting. Mu with 1.8% abamectin 1000 ml, 500 ml of Locust, mixed with water, sprayed on the surface immediately after the planting soil; or 0.5% avermectin granules 3-4 kg, pre-planting points.
6, pharmacy irrigation root. After planting, the plants in the sheds were partially affected, and 50% phoxim EC could be used 1500 times, or 80% dichlorvos EC 1000 times, or 90% trichlorfon crystals 800 times, and 0.25-0.5 kg per plant was sterilized. Kill root-knot nematodes in the soil.