At present, the most common nematode species in agricultural production are root-knot nematodes, cyst nematodes, root-rot nematodes, stem nematodes,semi-transmitted nematodes, leaf nematodes, and pine wood nematodes, among which root knot nematodes are most harmful. Nematode disease often has no obvious symptoms, is easily confused with deficiency traits, and forms complex infections with other pathogenic organisms.
According to statistics, the global nematicide market will reach US$1.2 billion in 2016, of which there is significant growth in the Asia Pacific and South America regions. At present, the market share of the world’s largest nematicides is for vegetables, followed by field and special crops. The output value of China’s pesticide market is about RMB 45 billion, while the output value of nematicide is about 500 million yuan, accounting for about 1%, and it has huge market development space.
Comprehensive control technology of nematodes:
(a) Agricultural control
- For crops with root-knot nematodes, it is best to implement crop rotations, especially rice rotate with onions and garlic. Do not rotate with nematode-prone vegetables such as eggplant, tomatoes, celery, lettuce, carrots and other vegetables.
- Seedbed disinfection or soilless seedling nursery bed is one of the important ways to prevent root-knot nematode transmission. If the seedbed is not treated, it is easy to spread the root-knot nematode to the field, and the crop yield is reduced a lot by the root-knot nematode. Using soilless seedlings is an important measure to avoid root knot nematode damage. If the seedbed area is large, measures such as disinfection of seedbeds can be used.
- Flooding nematode seriously affected field, irrigate 10-15cm deep for 20-30 days, the nematode died of hypoxia and suffocation. It is best to plant rice in this season, not only kills nematodes but also does not cause field waste.
- Deep-rooted root-knot nematodes which are mostly distributed on the topsoil, and deep-turning can reduce the damage. Deep plowing over 25cm before sowing and turning possible nematodes deep into the soil can reduce the damage.
- The use of anti-root-knot nematode varieties or stock selection of disease-resistant or disease-resistant vegetables, can greatly reduce the damage of various diseases.
(b) Physical control
Steam sterilization is harmless to humans and animals. The methods of steam sterilization include ground surface membrane disinfection method, buried underground pipeline method and negative pressure disinfection method, and the negative pressure sterilization method has the highest efficiency. Root-knot nematodes are very sensitive to heat and can kill almost all nematodes for 10-15 minutes at 50°C.
Soilless cultivation is an important agricultural measure that can effectively prevent root knot nematodes. According to the research, the use of soil cultivation tanks for the cultivation of vegetables, which is composed of rice husks, crop straws, and fermented materials for animal excrement, has the advantages of low cost, simple technology, and high product quality, and has broad application prospects.
(c)Biological and Microbiology for nematodes
Avermectin, Verticillium verticilliflora, Paecilomyces lilacinus, avermectin have a good effect on root knot nematodes, but it has been found through experiments that after continuous use of avermectin, The effect gradually decreased and it was not obvious when it was used initially.
Paecilomyces lilacinus is the most commonly studied and most widely used parasitic nematode egg parasite fungus, which can effectively control root-knot nematodes and cyst nematodes. The egg parasitism rate of the southern root-knot nematode is as high as 60% to 70%.