The root knot nematode disease of Chinese cabbage is mainly caused by the southern root-knot nematode, and the root-knot nematodes are mostly distributed in soil layers 20 cm away from the topsoil and are mainly active in soil layers of 3–10 cm.
The disease only occurred in the roots, and the symptoms of the aboveground parts were not obvious. The main symptoms were poor growth, short stature, wilting of plants when the air was dry, and sometimes necrotic and necrotic outer leaves, which could not be restored after topdressing. The roots of the diseased plants are underdeveloped, and the main and lateral roots are partially enlarged. There are many nodular nodules on the fine roots, which are milky white at first and later turn brown to form root knots. Cross-section of the root knot shows white pear-shaped female nematodes.
The disease is mainly based on agricultural control, especially for land that has already occurred or occurred. The prevention and control of diseases by pharmaceuticals is still focused on prevention. There are no good therapeutic agents. Once they occur, they can only be removed. Its comprehensive prevention can take the following methods.
The first is agricultural measures. We practice paddy-upland rotations, and turn cultivation with leeks, onions, and garlic, and use root-knot nematodes not to injure leeks to block their survival. Use disease-free seedlings. Deep plowing of soil promotes the death of nematodes. Remove severely ill strains and concentrate on burning them. In the summertime, the soil is treated with high temperature and flooded. After cleaning the garden, clean the ground and apply 500-1000 kg of straw and 200 kg of quick lime per acre. Then deep-dip 45-60 cm, ridging by a 40-cm row, 30 cm high, pouring a large amount of water in the ditch, so that there is a clear water in the ditch. . Cover the film on the ground so that the soil temperature of 20 centimeters underground is maintained above 50 °C for 15-20 days. After high-temperature treatment, apply 2-3 kg of 50% carbendazim WP or 50% carbendazim WP and 50% DM mixture of 50% DM WP to the ground. In the ground, it can effectively control root-knot nematodes, and it also has good control over other soil-borne diseases, weed seeds, and underground pests.
The second is chemical control. In the vicinity of planting and sowing, the following methods can be adopted: on the basis of applying base fertilizer and soil preparation, use 1.8% of avermectin EC 400-500 ml/mu, add 25-30 kg of sand, evenly spread. On the ground, turn to a depth of 10-12 cm and mix the medicine with sand. When planting or sowing, use 80-100 grams of soil inoculant per acre, add 25 kg of fine soil, evenly spread into the planting hole or sowing ditch (hole), and then use 80% of dichlorvos EC 1000 times water. The seedbed and the planting hole can also be irrigated with 1.8% avermectin EC 1500 times, and the application liquid 130 kg/mu. During the growth period, nematodes were found, and 50% phoxim EC 1500 times, or 80% DDVP 1000 times, and 90% dipterex crystals were used to irrigate the roots. Each irrigating solution was 200-300 ml. can.
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