Nematodes are the most abundant multicellular animals on the earth, and nematodes exist wherever there is water on the earth. Among them, plant parasitic nematodes account for 10%, and they cause harm to plant growth through parasitism, which is one of the important factors that cause major economic losses in agriculture and forestry. In field diagnosis, soil nematode diseases are easily confused with element deficiency, root cancer, clubroot, etc., leading to misdiagnosis or untimely control. In addition, root wounds caused by nematode feeding provide opportunities for the occurrence of soil-borne diseases such as bacterial wilt, blight, root rot, damping-off, and canker, resulting in compound infections and further increasing the difficulty of prevention and control.

According to a report, worldwide, the annual economic loss caused by nematode damage is as high as 157 billion U.S. dollars, which is comparable to that of insect damage. 1/10 of the drug market share, there is still a huge space. Below are some of the more effective products for treating nematodes..

1.1 Fosthiazate

Fosthiazate is an organophosphorus nematicide whose main mechanism of action is to inhibit the synthesis of acetylcholinesterase of root-knot nematodes. It has systemic properties and can be used to control various types of root-knot nematodes. Since Thiazophosphine was developed and produced by Ishihara, Japan in 1991, it has been registered in many countries and regions such as Europe and the United States. Since entering China in 2002, fosthiazate has become an important product for the control of soil nematodes in China due to its good effect and high cost performance. It is expected that it will remain the main product for soil nematode control in the next few years. According to the data from the China Pesticide Information Network, as of January 2022, there are 12 domestic companies that have registered fosthiazate technicals, and 158 registered preparations, involving formulations such as emulsifiable concentrate, water-emulsion, microemulsion, granule, and microcapsule. Suspending agent, soluble agent, compound object is mainly abamectin.

Fosthiazate is used in combination with amino-oligosaccharins, alginic acid, amino acids, humic acids, etc., which have the functions of mulching, promoting roots and improving soil. It will become an important direction for the development of the industry in the future. Studies by Zheng Huo et al. have shown that the nematicide compounded with thiazophosphine and amino-oligosaccharidins has a good control effect on citrus nematodes, and can effectively inhibit nematodes in and on the rhizosphere soil of citrus, with a control effect of more than 80%. It is superior to thiazophosphine and amino-oligosaccharin single agents, and has better effects on root growth and tree vigor recovery.

1.2 Abamectin

Abamectin is a macrocyclic lactone compound with insecticidal, acaricidal and nematicidal activities, and achieves the purpose of killing by stimulating insects to release γ-aminobutyric acid. Abamectin kills nematodes in crop rhizosphere and soil mainly through contact killing. As of January 2022, the number of domestically registered abamectin products is about 1,900, and more than 100 are registered for the control of nematodes. Among them, the compounding of abamectin and thiazophosphine has achieved complementary advantages and has become an important development direction .

Among the many abamectin products, the one that needs to be focused on is abamectin B2. Abamectin B2 includes two main components such as B2a and B2b, B2a/B2b is greater than 25, B2a occupies the absolute most content, B2b is trace amount, B2 is overall toxic and poisonous, the toxicity is lower than B1, the toxicity is reduced, and the use is safer and more environmentally friendly .

Tests have proved that B2, as a new product of abamectin, is an excellent nematicide, and its insecticidal spectrum is different from that of B1. Plant nematodes are highly active and have broad market prospects.

1.3 Fluopyram

Fluopyram is a compound with a new mechanism of action developed by Bayer Crop Science, which can selectively inhibit the complex II of the respiratory chain in nematode mitochondria, resulting in the rapid depletion of energy in nematode cells. Fluopyram exhibits different mobility in the soil than other varieties, and can be distributed slowly and evenly in the rhizosphere, protecting the root system from nematode infection more effectively and for a long time.

1.4 Tluazaindolizine

Tluazaindolizine is a pyridimidazole amide (or sulfonamide) non-fumigant nematicide developed by Corteva, used for vegetables, fruit trees, potatoes, tomatoes, grapes, citrus, gourds, lawns, stone fruits, tobacco , and field crops, etc., can effectively control tobacco root-knot nematodes, potato stem nematodes, soybean cyst nematodes, strawberry slippery nematodes, pine wood nematodes, grain nematodes and short-body (root rot) nematodes, etc.

Summarize

Nematode control is a protracted battle. At the same time, nematode control must not rely on individual combat. It is necessary to create a comprehensive prevention and control solution integrating plant protection, soil improvement, plant nutrition, and field management. In the short term, chemical control is still the most important means of nematode control with quick and effective results; in the long run, biological control will achieve rapid development. Accelerating the research and development of new pesticide varieties of nematicides, improving the processing level of preparations, increasing marketing efforts, and doing a good job in the development and application of synergistic auxiliaries will be the focus of solving the resistance problem of some nematicide varieties.