Root knot nematodes are nematodes, slender larvae, colorless and transparent, adult male and female heteromorphism, male adult linear, adult female duck pear-like. The larvae live in the soil and usually invade the root from the root tip and colonize the roots to grow.
First, the incidence conditions
Root-knot nematodes are aerobic, preferring dry, loose, sandy loam, damp, clay ground, compacted soil, and saline-alkali fields. The most suitable temperature for nematode life is 25-30 degrees Celsius, which is higher than 40 degrees. It is rarely active below 5 degrees, and the soil temperature is 55 degrees after 10 minutes. There are two peaks of nematode in one year, one is from April to May, and the other is from September to October. The high temperature in summer and the low temperature in winter occur less. Nematodes distributed at 20 cm below the topsoil, of which 5 to 10 cm are the most, because the topsoil 1 - 5 cm is too dry, deep 20 cm above the permeability is poor, are not suitable for life.
Second, the occurrence of harm
The occurrence of root knot nematode disease has become increasingly serious in recent years. Mainly for southern root-knot nematodes, root-knot nematodes have a wide host range. Except for garlic, green onions, leeks, and hot peppers, most other crops are harmful. Adults (4 instars) are divided into female and male adults. The males leave the roots. In the earth, the females remain in the roots and can be mated (sexually) or non-mating (partly) spawning. It takes about 1 month to complete the above life cycle, and 5 to 10 generations can be completed throughout the year. In the northern greenhouse, root-knot nematodes live over winter with eggs and larvae. The exudation of nematodes in the root stimulates the swelling of the root cortex, forming a distinct nodule or root knot. Due to root damage, the transport of water and nutrients is hindered and the plants are dwarfed, yellowed and withered.
The nematode eggs and the 2nd instar larvae overwinter in the soil with the diseased body, the scope of its own activities is very small, mainly by diseased soil, diseased seedlings, running water, cultivation, transportation and other artificial transmission. In addition, the solar greenhouse has created favourable conditions for the growth and reproduction of nematodes. In recent years, it has repeatedly plucked and planted single crops. The treatment of nematode disease residues has not been thorough, and the number of remnants of nematodes has increased dramatically, causing nematode disease to become increasingly serious.
Third, control methods
(1) Completely remove the diseased body, increase the application of Keguang organic fertilizer or organic fertilizer containing Avi component. After the crop is harvested, all the diseased roots will be removed, and buried or burned in a concentrated manner. Don't throw it away. Do not use the diseased body to irrigate the soil, do not use the soil to raise seedlings, and strictly prevent transmission. Increase organic manure, reduce fertilizer use, promote the formation of soil aggregate structure, improve soil structure, and inhibit the occurrence of root-knot nematodes.
(2) Cultivate disease-free strong seedlings. The selection of resistant varieties and the use of resistant rootstocks for grafting are relatively effective methods. When growing seedlings, bedless soil should be used, then bed soil should be treated with pesticides, and seedlings should be sown.
(3) Chemical control. For adult diseased trees, the use of dibromochloropropane has a good control effect. In general, 80% dibromochloropropane 40-60 ml per plant is used, and 7.5-15 kg of water is weighed. Every 30 centimeters around the tree trunk is used as a hole. The distance between the hole and the hole is 15 centimeters or more. The liquid is poured into each cavity evenly, then the cover is solid, and a small amount of water is poured on the surface of the cave to cover it.
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