(1) Living habits and hazard characteristics: Root-knot nematodes are very serious in some areas. The disease mainly occurs on fibrous roots or lateral roots, and the diseased part produces swollen and deformed nodular nodules, and there are very small milky white nematodes buried in the anatomical root nodules. Generally, a thin new root can be born above the root knot, and it will be reinfected to form a root-like tumor. At the beginning of the disease, the symptoms of the aboveground parts are not obvious, but after a period of time, the plants show yellowing leaves, poor growth, few fruits, and even short plants in severe cases. Infected plants often wilt at noon in dry or sunny weather, and some die early.
The pathogen of pepper root-knot nematode disease in China is Meloidogyne incognita, which belongs to plant parasitic nematodes, with male and female larvae in the form of slender worms. Most of the eggs laid by females are buried in the host tissues. Root-knot nematodes often overwinter in the soil with the second instar larvae or eggs, and can survive for 1 ~ 3 years. The next year, when the conditions are suitable, the overwintering eggs hatch into larvae, continue to develop and invade the host, stimulate the proliferation of root cells and form root nodules or tumors. When the larvae develop to the 4th instar, they mate and lay eggs. The males leave the host and enter the soil, and soon die. The eggs hatch and develop in the root knot. After the 2nd instar, they leave the egg shell and enter the soil for reinfection or overwintering. The primary infection sources of pepper root-knot nematodes are mainly diseased soil, diseased seedlings and irrigation water. When the soil temperature is 25 ~ 3℃ and the soil water capacity is about 4%, the pathogenic nematodes develop rapidly, and the larvae stop moving below 1℃ and die after 1 minutes at 55℃. The conditions of high and dry terrain, loose soil texture and low salt content are suitable for nematode activity and the disease is serious; Continuous cropping is seriously ill.
Root-knot nematodes overwinter in diseased tissues as adults or eggs, or overwinter in soil as larvae. Sick soil and fertilizer are the main sources of disease. In the following year, overwintering larvae or eggs hatch into larvae, which invade from the roots, leading to initial infection in the field, and then repeated infection. The suitable development temperature of pepper root-knot nematode is 25 ~ 3℃, and the larvae lose their vitality when they meet the low temperature of 1℃, and die after 5 minutes at 48 ~ 6℃. This nematode can only survive in the soil for one year. It is distributed within 2 cm soil layer, with the most distribution in 3 ~ 1 cm soil layer. Root-knot nematodes are aerobic. Any soil with high and dry terrain and loose soil is conducive to nematode activity, and the disease is serious. If the soil is wet and hardened, it is not conducive to nematode activity and the disease is light. Continuous cropping is serious, and the longer the continuous cropping period, the more serious the harm. The incidence in spring is heavier than that in autumn.
(2) control measures: ① reasonable rotation. Pepper rotation for more than 3 years, it is best to carry out paddy-upland rotation. Seriously ill plots can be replanted with onions and garlic vegetables. ② Carry out deep ploughing. Root-knot nematodes generally move in shallow soil layers, and deep tillage can reduce the harm of root-knot nematodes. It is usually necessary to plow more than 25 cm. ③ Clean up the sick and disabled bodies in time and disinfect the soil. After harvesting crops in spring, using the high temperature in summer, 75 ~ 1 kilograms of quicklime is sprayed every 667 square meters, then the ground is turned over, filled with water, covered with plastic film, and the greenhouse is closed for 15 ~ 2 days. The surface temperature can reach 7℃, and the temperature of 1 cm soil layer can reach 6℃, which can kill nematodes. ④ Chemical control. When sowing or planting, 1% Man Ku granules are applied to holes at 5 kg per 667 square meters, or 5% Man Ku granules at 1 kg per 667 square meters, or 98% ~ 1% Mianlong granules at 5 ~ 6 kg per 667 square meters (6 ~ 7 kg of sticky soil), and 5 kg of fine soil is evenly mixed, and the application depth is 2 cm. 1.8% Efuding EC can be used to irrigate ditches before planting, and the dosage is 1-1.5g per square meter and 6kg of water. After planting, the roots can be irrigated twice with the same dosage, with an interval of 1-15 days. In addition, 7-9 times solution of Chinese soil bacteria and insects or 1 times solution of 8% dichlorvos EC can be used to irrigate the roots, or 3 kg of 3% Mi Le Er granule and 5 kg of dry fine soil can be applied to the soil. During the growth period, the roots can be irrigated with 1 times of 5% phoxim EC (used in greenhouse) or 1 times of 8% dichlorvos EC (used in open field), and each plant can use .25 ~ .5 kg of liquid medicine.