When the average soil temperature is 15-30 °C, the growth and reproduction rate of root knot nematodes is significantly accelerated, about 20 days to complete the parasitism, infection, reproduction, re-infection of the entire stage of life history, and now with the gradual increase in temperature, the ground temperature has gradually reached the most suitable growth and breeding temperature of nematodes, and the harm of nematode infestation must be prevented.
However, now on the market nematode preparations are very mixed, a wide variety of varieties, how to choose the right line preparations, in order to better protect the healthy growth of crops, the following plant protection family summary of some mainstream nematode preparations, compared with the advantages and disadvantages, to help growers better choice to use!
First, small nematodes are harmful
Nematodes, also known as root-knot nematodes, are known to be vegetable-infested nematodes mainly include high arch root knot nematodes, peanut root knot nematodes (there are about 330 kinds of infested crops), northern root knot nematodes (about 550 kinds of infested crops), southern root knot nematodes, Java root knot nematodes and beet root knot nematodes, etc., which can damage more than 3,000 crops in 114 families. Light yield loss in 20%-40%, serious up to 70% or more, and some even fail to harvest!
Mainly harmful to the roots, pathogenic nematodes parasitize between the root bark and the middle column, so that the root tissue overgrows, resulting in the formation of rhizobia of different sizes.
Therefore, the root is nodular and enlarged, which is the main symptom of the disease. Most nodules occur on fine roots, and when the infection is severe, secondary nodules can appear, and a large number of small roots occur, so that the root system is coiled into clumps and forms a whisker root mass. Because the root system is damaged, affecting normal function, making it difficult to transport water and nutrients, coupled with the rot of old mature rhizomas, and finally necrosis of diseased roots.
Under the general incidence of disease, there are no obvious diseases in the aboveground part of the diseased plant, but as the root damage gradually becomes serious, the canopy appears weak branches, smaller leaves, growth decline and other pathologies. When the damage is more severe, the leaf color is yellow, dull, the leaf margin is curled, it is water-scarce, the leaves are yellowed, deciduous, leaflets or leaf deformities, and in severe cases, the plant wilts, etc.; it can cause dry heart or hollowness, and flower rot often occurs when flowering.
Second, the reason why nematodes are difficult to control
1. The reproduction speed of multiple types is extremely fast:
Root-knot nematodes can reproduce both sexes and parthenogenesis, with 300 to 800 eggs per egg sac, which can reproduce 5-10 generations a year and overlap generations
2. The eggs are strong in survival and are not easy to kill:
Although a large number of chemical control agents kill the adult nematodes, but the chemical agents can not kill the eggs of the worms, the eggs are only poisoned into the dormancy period, in the right temperature environment, they can resume growth, re-infect the harmful crops, some people use to reduce or increase the soil temperature, kill the nematodes, but some of the cystic nematode eggs, can also survive in the soil for 2-5 years, some nematode eggs can survive for 28 years in the absence of a host in cold areas.
3. Expansion of the breeding environment:
There are many vegetables and orchards using unripe and complete organic fertilizer, especially chicken manure, which contains a large number of nematode eggs, while the greenhouse provides a breeding place for nematodes, so that nematodes have a suitable winter habitat, so that the nematodes team gradually expands, and the harm is serious year by year!
4. The resistance of cultivated varieties is not strong:
Nematodes are the most serious pests of cucurbitaceae melon vegetables cucumbers, watermelons, melons, loofahs, bitter melons, etc., including grafted rootstocks, all of which have no resistant varieties. Legume vegetables (kidney beans, carobs, lentils, knife beans, etc.) also have no line varieties.
5. Poor awareness of prevention and control of farmers:
Nematode disease is more about prevention than treatment. The initial symptoms of nematode disease are in the underground part, which is easily ignored by farmers, and when it is found, the symptoms are already more serious, and it is difficult to prevent and control! Most of the chemical control agents are to kill adult nematodes, and the killing of insect eggs is not strong. And the next generation of nematodes will become resistant and resistant to chemical pesticides!
6, chemical pesticides have developed resistance:
The long-term use of chemical pesticides in the process of controlling root-knot nematodes has produced serious resistance and drug resistance, such as: avermectin, thiazolephosphine, etc., although it can kill nematode larvae, but it is difficult to kill old adults and eggs.
Third, the comparison of nematode control agents
1. Fumigator
Fumigator-type nematodes are used to kill nematodes by spreading volatile liquids or gases in the soil, but most varieties have been banned due to environmental safety issues.
(1) Halogenated hydrocarbons
There are mainly varieties of chlorinated bitter, bromomethane, dibromoethylene, 1,3-dichloropropene, dibromochloropropane and D-D mixture. This kind of nematode is used earlier in production, is a soil fumigant, has a high vapor pressure, diffuses in the soil through the agent, the mechanism of action is to react with the nematodes in the soil protease, so that the nematodes lose activity, resulting in the death of nematodes, directly poisoning the nematodes. The above ingredients destroy the ozone layer, except for chlorinated bitters, which are banned. Serious damage to the environment and toxic to people, the use of the need for special machinery and wear special protective clothing, if the supporting technology can not keep up, will have potential harm to the applicator.
(2) Methyl thioisothiocyanate
There are mixtures of cotton, villerobimus and diagonal esters. These nematicides can release methyl thioisocyanate, that is, carbamate ion and nematodes in the body of the protease to death from carbamate poisoning. However, these agents need to be evenly distributed to achieve the desired effect, usually require special application equipment, and improper use can cause harm or poor results. Due to the large amount of these drugs, the agricultural cost is also high, which is difficult for general growers to bear, and most of them are already within the scope of prohibition and restriction.
2. Organophosphorus
Organophosphorus line killer is not directly to kill nematodes, but anesthesia and affect the feeding, development and reproduction of nematodes, acting on acetylcholinesterase, delaying its invasion and harm to crops, common thiazoliphos, gram line phosphorus, line phosphorus, thiophosphate, chlorzophos, methyl isotylinphos, worm line phosphorus, line phosphorus, filamentous phosphorus, foonsin, line phosphorus, etc., there are certain residues in the soil, most of which have been within the prohibited limits. For example, sulfur phosphorus is prohibited, methyl isosyphos, line-killing phosphorus, chlorzophos, etc. are prohibited from being applied to vegetables.
3. Carbamates
KBUV, Chlorpyrifos, Killline, Jiuxiaowei, Butyrothio Budweiser, etc. This type of assortment has a strong suction effect. The mechanism of action is mainly to damage the nervous system, reduce the migration, infestation and feeding of nematodes, thereby reducing the reproduction and harm of nematodes, and organophosphorus, can not directly kill nematodes, but only act on the nervous system in the nematodes, affecting nematodes. Most of them are already within the scope of prohibition, such as Carbufuran and Slub, which are prohibited from being applied to vegetables.
4. Antibiotics
The most common agent is avermectin, which has a good effect on root-knot nematodes in the early stage through a unique touch killing effect, but after testing, it was found that after the continuous use of avermectin, its effect gradually decreased, without the initial use of obvious, followed by avermectin B2, which is also a broad-spectrum nematode preparation, but sensitive to light, pay attention to the timing and dosage of medication, and currently have different degrees of resistance.
5. Microorganisms
At present, it is confirmed that the microbial bacteria with the function of killing the line are purpuric violet spores (Penicillium lilac), Pachychophyllum pachyderma, and its compound microbial bacteria, the rest of the strains are ineffective against nematodes, using the strong penetration, parasitism and strong reproducibility of the complex microorganisms, after being applied to the soil, the complex microbial bacteria quickly germinate and grow a lot of hyphae, the hyphae touch the eggs of the nematodes, can secrete chitinase, and then penetrate the egg shell, with the intra-egg material as the nutrient for a large number of reproduction, so that the cells inside the nematodes and early embryos are destroyed, thereby reducing and killing nematodes.
However, ordinary strains are affected by climatic conditions, and only with good coating carrier technology can they achieve very good results.
6. Plant essential oils
Plant-derived biological preparation plant essential oil is extracted from a variety of highland plants, compatible with the environment, biodegradable thoroughly, not the use of toxicity to kill nematodes, but the use of special plant essential oils of infiltration, spreading, high adhesion, change the mucus of the surrounding environment of nematodes, so that nematodes in the soil and other pests (grubs, maggots, etc.) that migrate slowly are closed and blocked, blocking the valve, making it unsuitable for the living environment, resulting in nematodes and other underground pests completely dying and decomposing in the soil, and are permanent. Won't bounce back to resurrection!
And special plant essential oil is a concentrated essential oil refined and extracted from the flowers, stems, seeds and roots of different plateau plants, for nematode control, no need for fumigation, can be prevented, does not hurt the roots, does not hurt the seedlings, safety and environmental protection without residue, no matter how much it is used, how many times it is used, the melons, fruits and vegetables picked can be eaten directly, will not cause harm to people and animals, and will not be used for a long time and produce resistance.
Its unique mechanism of action not only kills nematodes but also purifies the soil environment, can clean up harmful bacteria in the soil, cut off their food chain and starve to death, while nematode vegetable oil can also decompose some beneficial substances to stimulate crop root growth, quickly repair broken root systems, so that plants are robust and not susceptible to disease, increase production and income.
Whether the effect is good or not, you will know by comparing it
Control test products: nematode plant essential oil, 10% thiazolium granules (market purchase of a major company brand), 20% thiazole phosphorus water emulsion, 1.8% avermectin emulsion, avermectin. Thiazolidine, common biologically derived defensive line agent, controllable (line of defense control), water
From the above results, it can be seen that nematode vegetable oil is more rapidly killed than conventional agents for the control of root-knot nematodes, and under the condition of conventional dilution multiples, the efficacy is better than that of conventional pesticide varieties
Through field experiments, it has been shown that the use of selected nematode vegetable oil dilution of 1200 times can effectively control the harm of root-knot nematodes, prevent root-knot nematodes, use this product 500-1000ml per mu, use 1000-1500ml per mu in serious areas, start from colonization, under normal circumstances, a crop variety can be used once from colonization to harvesting, and individual serious areas can be used again one month or two months after the first use.
Fourth, the advantages of nematode plant essential oils
1, nematode plant essential oil is derived from a variety of plant extracts, the original ecology, and plants have the best affinity, through the active ingredient extraction and accurate proportion of mixed preparation, does not contain hormones and pesticide components, non-toxic and harmless.
2, no need to fumigate, can prevent and treat, do not hurt the roots, do not hurt the seedlings, safety and environmental protection without residue, can be picked and eaten after use, green and healthy no resistance, long-lasting effect!
3, fast-acting, 12 hours under the microscope observation, nematode mortality rate of up to 99% or more, permanent death, will not rebound resurrection!
4. Not only kill nematodes, but also kill slower moving underground pests, such as maggots, grubs, etc., and avoid other underground pests without harming the root system.
5. Purify the soil environment, clean up the harmful bacteria in the soil, cut off the food chain of the harmful bacteria so that the bacteria starve to death, stimulate the growth of the root system, and quickly repair the damaged root system.