Although plant parasitic nematodes belong to nematode hazards, they are not plant pests, but plant diseases.

Plant nematode disease refers to a type of nematode that can parasitize various tissues of plants, cause plant stunting, and transmit other plant pathogens while infecting the host, causing plant disease symptoms. Plant parasitic nematodes that have been discovered so far include root-knot nematodes, pine wood nematodes, soybean cyst nematodes and stem nematodes, forerunner nematodes etc.

Take root-knot nematode as an example:

Root-knot nematodes are a very important class of plant pathogenic nematodes that are widely distributed all over the world. In tropical and subtropical regions with abundant rainfall and mild climate, the harm of root-knot nematode is particularly serious.

Since most nematode diseases occur on the roots of plants, it is difficult to apply pesticides. And it is very easy for generations to overlap in vegetable greenhouses, which seriously occurs, so root-knot nematodes are generally difficult to control.

Root-knot nematode has a wide range of hosts, and can parasitize more than 3000 kinds of hosts such as vegetables, food crops, cash crops, fruit trees, ornamental plants and weeds. After vegetables are infected with root-knot nematode, the above-ground plants are short, the branches and leaves are shrunk or yellowed, the growth is stunted, the leaf color is lighter as if lack of water, the growth of seriously ill plants is weak, the plants are wilting in drought, and the whole plant dies in severe cases.

Traditional nematicides can be divided into fumigants and non fumigants according to the different methods of use.

Fumigant

It includes halogenated hydrocarbons and isothiocyanates, and non fumigants include organic phosphorus and carbamate. Methyl bromide and chloropicrin are halogenated hydrocarbons, which can inhibit the protein synthesis of root knot nematodes and the biochemical reaction in the respiratory process; Carbosulfan and Mianlong belong to methyl isothiocyanate fumigants, which can inhibit the respiration of root knot nematodes to death.

Non fumigation type

Among the non fumigant nematicides, thiazolphos, phoxim, phoxim and chlorpyrifos belong to organic phosphorus, carbofuran, aldicarb and carbofuran belong to carbamate. Non fumigant nematicides destroy the nervous system function of root knot nematodes by binding to acetylcholinesterase in the synapses of root knot nematodes. They usually do not kill root knot nematodes, but can only make root knot nematodes lose the ability to locate the host and infect, so they are often called “nematode paralysis agents”.

At present, there are not many new nematicides, among which fluorenyl sulfone, spiroethyl ester, bifluorosulfone and fluconazole are the leaders. Abamectin and thiazolophos are also frequently used. In addition, in terms of biological pesticides, Penicillium lilacinus and Bacillus thuringiensis HAN055 registered in Konuo also have strong market potential.