RU2800610C1 - Long-lasting biocide for soil application - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: long-lasting biocidal agent for soil use contains a systemic preparation in the form of a nematocide-insecticide from the group of carbamates and a biodegradable material, which is used as polycaprolactone mixed with organically modified clay. The components of the biocidal agent are used in the following ratio (wt%): nematocide-insecticide 10-20; polycaprolactone 40-75; organically modified clay 5-50. Oxamyl ((EZ)-N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)acetamide), or thiodicarb, or carbaryl, or propoxur is used as a nematocide-insecticide of the carbamate group.

EFFECT: proposed long-lasting biocidal agent for soil application provides a gradual and long-term effect of the nematocide-insecticide, is highly environmentally friendly and highly effective in combating the cyst-forming potato nematode.

2 cl, 3 dwg, 4 tbl, 2 ex

Description

The invention is a plant protection product containing a systemic preparation and a biodegradable polymer carrier material, and can be used to combat potato cyst nematode.

Potato cyst nematodes, represented by G. rostochiensis and G. pallida, are the most important potato nematode pests and are subject to strict quarantine regimes in more than 100 countries. The quarantine status of potato nematodes is partly due to their ability to form dormant structures known as cysts, which consist of the hardened body of females 0.5 mm in diameter, each containing approximately 300-500 eggs. In Russia, the RoI G. rostochiensis pathotype predominates, representing the greatest economic problem in the field of potato production. As means of protecting potatoes from nematodes, nematicides are used, which are a group of pesticides and include a number of chemical compounds that differ in the mechanism of action, as well as in the method of application and the form of deposition.

The most common deposited forms of nematicides are in the form of aqueous suspensions, dispersions, emulsions for seed treatment, plant spraying and soil treatment.

Known composition of the suspension concentrate for combating nematodes [patent RU 2773720] containing N-{[3-chloro-5-(trifluoromethyl)-2-pyridinyl]-ethyl}-2,6 dichlorobenzamide (fluopyram) and PEO-PPO-REO block -copolymers. However, the preparation of this composition is very laborious and includes 5 stages from the preparation of the gel, thickener and modifier with biocides with grinding the suspension and mixing with a rotary-stator mixer until the particle size of the component is reached, followed by grinding in a ball mill containing an abrasive material and combining with the gel . The composition also contains formulations selected from the group consisting of antifreeze, dye, pH regulators, buffers, stabilizers, crystal growth inhibitors or micronutrients, surfactants. An undesirable effect may be an increase in the particle size of the composition during storage of the product.

Known drug with the properties of a soil nematicide, based on one or more crystalline or aqueous solutions of non-reoxide chemical compounds [patent RU 2261597 C2]. Soil treatment with crystalline complex peroxide compounds in doses of 100-200 g/m ² or their 0.1-3% aqueous solutions at a consumption rate of 5-10 l/m ² reduces toxicity and improves the environmental safety of pesticides. However, peracetic acid is actively processed by soil microflora, as a result of which the effect of this drug is limited in time.

A known composition for seed treatment [patent RU 2759449], containing an aqueous polyurethane dispersion; and one or more insecticides, fungicides, nematicides and/or pesticides, where the aqueous polyurethane dispersion forms a film showing: microhardness not more than 15 N/mm ² ; (Tg from -54°C to -4°C; elongation in percent from 44 to 820; and tensile strength from 130 psi (9.1 kg/ ^{cm 2 /} 0.9 megapascal (MPa)) to 1300 psi (91.4 kg/cm ² /9.0 MPa) As polymers, polymers from the group of polyvinyl ethers and complex polyvinyl ethers (polybenzyloxyethylene ^, polyvinylacetal, polyvinyl acetate, polyoxytetramethylene, polycarbonates, polysiloxanes, polyurethanes, polyacrylamides and etc.) Seeds that can be treated in this way are sown by means of, for example, a seeder with a pneumatic seeder (corn seed, cotton seed, sorghum seed, oat seed, rye seed, barley seed, soybean seed, vegetable seed, wheat seed, sugar beet, rice, sunflower seed, lettuce seed, and spinach seed), but field performance data is not included in the patent.

Known microencapsulated suspension [patent RU 2709172] for the treatment of plants containing a compound oil core containing a pesticide-active agent dispersed in an oil compound and an aqueous solution containing a polycationic colloid and a polyanionic colloid in a ratio of 0.02 to 1% by weight, and polyanionic colloid from 0.02 to 2% by weight, and a pH regulator.

Known aqueous insecticidal and/or nematicidal composition for seed treatment in the form of a suspension intended for seed treatment [patent RU 2395965], including: insecticide and/or nematicide in an amount of at least 3 wt. % and 1-25 wt. % based on the total weight of the composition of at least two surfactants, where one is an anionic phosphate compound and the other is a nonionic alkoxylated phenol, the mass ratio is from 1:10 to 10:1. The composition also includes a polymer used as a carrier. Suitable polymers are selected from the group consisting of: ethylene-vinyl acetate copolymers, vinyl acetate/vinylpyrrolidone copolymers, alkylated vinylpyrrolidone copolymers, polyvinylpyrrolidone, and polyalkylene glycol, including polypropylene glycols and polyethylene glycols. For the preparation of such compositions, the pH of pesticides is of great importance, since low pH values can affect the quality of the suspensions.

A composition is known [patent RU 2409953] containing a nematicide, lecithin (non-ionic emulsifier) and a surfactant in water. In various embodiments, the implementation of the concentration of the active ingredient in aqueous solution can be from 6.1 to 20%. Other concepts of the present invention describe a composition containing sesame oil, lecithin and a compound selected from the group consisting of triglycerides, diglycerides, sugar alcohols, ethoxylated monoglycerides, fatty acid ethoxylates, sorbitan monoester, etc.

The disadvantages of the above analogues include the complexity of the composition of the compositions, the complexity of their manufacture, which requires special precautions.

One of the promising directions for increasing the effectiveness of pesticides, including nematicides, is the development and use of special forms with a long-term release of the active substance. On the one hand, this will help to avoid peak and often toxic concentrations for non-pathogenic species, and on the other hand, it will allow maintaining an effective dose of the drug for a long period of time.

The key to creating such sustained systems is the carrier material used as the base for the active ingredient to be applied. For this, various materials of synthetic and natural origin are used. The use of synthetic materials that do not decompose in the natural environment can create an environmental problem of their accumulation in the biosphere in the form of foreign compounds and even pollutants. The use of biodegradable polymers is preferred in the development of such carriers. Positive results of research and application for the introduction and slow release of pesticides of various nature have already been found for such natural polymers as cellulose, starch, alginate, albumin or gelatin, as well as polyhydroxyalkanoates, copolymers of lactic and glycolic acids, polycaprolactone, peat, clay, etc.

Known composition [patent EP 3197273 B1] in the form of granules containing the active ingredient (insecticide, fungicide, acaricide, nematicide) and polymeric material (modified and/or unmodified cellulose), adjuvant and surfactants (laurate-sucrose). Granules consisting of pesticide from 1 to 5%, cellulose 5-8%, surfactant 6%, cross-linking agent 3% and a combination of fillers from 78 to 90% have proven effectiveness. However, such granules have a complex composition and excipients (surfactant, cross-linking agent, filler).

Known microcapsules from 0.2 to 200 microns [patent US 20060193882], containing a fungicide or insecticide intended for ground use. The ratio of fungicide and polylactide (drug carrier) is from 1:99 to about 1:1. Degradation of the polymer in a certain period of time leads to slow release of the fungicide and prolonged action, the rate of degradation depends on the fungicide/polymer ratio. However, the use of a hydrolysable polymer may result in an uncontrolled release of the drug.

A long-acting herbicide for soil pre-emergence application is known [patent RU 2494621], containing a systemic herbicide "Zellek-super", deposited in a polymeric metric from biodegradable polymers of poly-3-hydroxybutyrate and poly-3-hydroxybutyrate -3-hydroxyvalerate in the form of films and microgranules The disadvantage of the invention is the use of organic solvents to obtain carrier forms and uncontrolled deposition of substances, the possibility of binding the active ingredient to the solvent.

The closest technical solution adopted as a prototype is a long-acting pesticide for soil application [patent RU 2733295, published 01.10.2020]. The pesticidal agent contains a pesticide and a carrier material. As a pesticide, a systemic preparation of herbicidal or fungicidal action was used, as a carrier material - degradable polymer poly-3-hydroxybutyrate mixed with natural material - sawdust, or peat, or clay in the following ratio of components, wt. %: pesticide 10-20; polymer poly-3-hydroxybutyrate 50; natural material 30-40.

The disadvantages of this composition are: the use as a carrier material expensive for widespread use of the polymer poly-3-hydroxybutyrate; the use of a rather labor-intensive technology for the manufacture of the composition; the use of birch sawdust, which retain moisture and can be an additional source of fungal contamination.

The objective of the invention is to reduce the cost of the composition through the use of economically available materials, and reduce the complexity of its manufacture.

The task is achieved by the fact that in a long-acting protective biocidal agent for ground use, containing a systemic preparation and a biodegradable material, according to the invention, a nematicide-insecticide from the group of carbamates is used as a systemic preparation, and polycaprolactone (PCL) is used as a biodegradable material in a mixture with organomodified clay, in the following ratio of components, wt. %:

nematicide-insecticide 10-20; polycaprolactone 40-75; organic-modified clay 5-50.

Oxamyl ((EZ)-N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)acetamide) or thiodicarb, or carbaryl, or propoxur was used as a nematicide-isecticide of the carbamate group.

Chemically modified montmorillonite (MMT) was used as an organo-modified (organophilic) clay.

The technical result is ensured by the fact that the composition is made from a mixture of polymers using extrusion technology in the form of solid granules that are slowly destroyed in the environment with a half-life of at least 50 days, and also by the fact that it is able to prolong the action of the nematicide-isecticide from the group of carbamates - oxamil (( EZ)-N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)acetamide) or other drugs of the same group (thiodicarb, carbaryl, propoxur).

The invention is illustrated by graphic materials.

In FIG. 1 shows photographs of PCL/MMT oxamyl pellets with different inclusions of MMT: 1 - 5%; 2 - 10%; 3 - 25%; 4 - 50%.

In FIG. 2 shows x-rays of MMT (1), PCL (2) and PCL/MMT granules obtained by extrusion with the inclusion of MMT: 3 - 5%, 4 - 10%, 5 - 25%, 6 - 50%.

In FIG. 3 shows the IR spectra of pure oxamyl and PCL/MMT beads with oxamil.

In FIG. 4 - output of oxamil from the commercial preparation Vidat® 5G (control), PCL+oxamil granules and PCL/MMT granules, depending on the inclusion of MMT, within 30 days.

For the preparation of the claimed biocidal protective agent, polycaprolactone (PCL) granules are used with a weight average molecular weight (M _w ) 80 kDa, a degree of crystallinity (C _x ) 52%, a melting point (T _pl ) 90°C (Sigma Aldrich, USA); organophilic clay "Monamet-101" - chemically modified montmorillonite (MMT) ("Metakley", Russia), in the form of a powder with a particle size <125 microns. Oxamyl (in the form of a solution) (CityLab, Russia), a widely used nematicide from the class of carbamates, was chosen as the insecticide nematicide. The insecticide nematicide was mixed with clay and polycaprolactone granules in the proportions indicated above. The biocidal agent in the form of granules was obtained using a portable extruder (Bestfillaments, Russia) at a melting temperature of 90°C. The biocidal agent consists of PCL/MMT granules with various inclusions of MMT (5, 10, 25, 50% by weight of the polymer and with the inclusion of oxamyl 10-20% by weight of the granules. The image of the granules is shown in Fig. 1. To determine the physicochemical properties composite PCL/MMT granules, IR spectroscopy, X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC) were performed.

X-ray diffraction patterns of PCL/MMT composite granules were obtained on a D8 ADVANCE X-ray diffractometer (Bruker AXS, Germany) in the range of 4÷60° angles 2Ө. The identification of the chemical structure of the samples was carried out by Fourier transform infrared spectroscopy (IR-Fourier spectroscopy) using a Nicolet iS10 spectrometer manufactured by Thermo Scientific (USA) using a GTX Smart attachment (Thermo Scientific) with a diamond crystal by the method of frustrated total internal reflection (FTIR). Calorimetric measurements in the mode of temperature modulation of the heat flux of the samples were performed using a DSC25 differential scanning calorimeter manufactured by TA Instruments (USA) in standard aluminum crucibles in an atmosphere of pure _N2 . at a flow rate of 70 ml/min.

The IR spectrum of oxamyl contained peaks at 1656 cm ^-1 , 2945 m ^-1 and 3308 cm ^-1 corresponding to ON bonds, valence CH bonds, NH bonds. The IR spectra of PCL/MMT beads showed characteristic peaks for PCL and MMT, corresponding to the peaks described above. The intensity of the peaks in the region of 2945 cm ^-1 and 3340 cm ^-1 changed depending on the inclusion of MMT: with the inclusion of MMT 5 and 10%, a decrease in the intensity (height) of the peak in the region of 1656 cm ^-1 , 1500 cm ^-1 and 1571 cm could be observed ^-1 , and the shift of the peaks in the region of 3308 cm ^-1 . The incorporation of MMT 25 and 50% in the PCL/MMT oxamyl pellets resulted in the disappearance of the peak at 3340 cm ^-1 .

Exit of oxamil. (solubility 280 g/l) from the resulting PCL/MMT composite granules were studied under laboratory conditions in vitro. To do this, the PCL/MMT granules of each group (each weighing 100 mg) were placed in conical flasks with 50 ml of distilled water. The flasks were incubated at 22–25°C in a thermostat TS 1-80 (Russia). Samples (1 ml) were taken into sterile eppendorfs the first 1, 2, 4, 6, 8 hours and after 1, 2, 4, 8, 14, 20, and 27 days. After each sampling, distilled water (1 ml) was added to the flasks to maintain the initial volume. Oxamyl concentrations were analyzed by high performance liquid chromatography on an Agilent 1200 chromatograph (Agilent Technology, USA) equipped with a diode array detector at a wavelength of 220 nm using an Agilent Eclipse XDB-C18 column, followed by conversion to the actual concentration, taking into account the withdrawal of samples and adding water.

It is known that the release of drugs from polymeric forms in an aqueous medium occurs in several stages: (1) dissolution of the drug from the surface of the polymer carrier; (2) penetration of the solvent (water) into the polymer carrier; (3) dissolution of the drug in the carrier itself; and (4) release of the drug into the aqueous medium by diffusion. Data confirming the sustained release of the developed PCL/MMT beads are shown in FIG. 4.

In contrast to the obtained PCL granules and PCL/MMT granules with oxamyl, the yield of oxamil from Vidat® 5G was about 100% in the first hour and after 24 hours began to decrease until the end of the experiment. This effect is associated with the hydrolysis of the drug to oxamyl oxime. The release of oxamyl from PCL and PCL/MMT granules into water took place without sudden releases and by day 8 (192 h) was 5% for PCL, PCL/MMT, 10% PCL/MMT, 25% PCL/MMT and 50% PCL/MMT , respectively, 58%, 34%, 60%, 52% and 80% of the original. On the 20th day (480 h) of the experiment, the concentration of oxamyl in water decreased from PCL and PCL/MMT 50% granules. Despite this, an increase in the concentration of MMT in the granules contributed to an increase in the yield of oxamyl, and on day 30, the maximum yield of oxamyl was recorded for PCL, PCL/MMT 25% and PCL/MMT 50% granules, which corresponded to 73%, 80% and 97%. In PCL/MMT granules containing 5 and 10% MMT, the yield of oxamil was 40 and 70%.

The result obtained allows us to conclude that oxamyl is highly hydrolyzed in aqueous media and that it needs to be encapsulated in polymer carriers to obtain a long-term effect. Based on the study and biodegradation of granules for further experiments, among the obtained forms of PCL/MMT granules, granules with an MMT inclusion of 50% were selected.

The proposed tool is effective, environmentally friendly, it has been proven to prolong the nematicidal action of oxamil by 2-2.5 times. In addition, the protective agent has a lower cost due to the use of economically available materials.

The preparation and use of the claimed non-manticidal granules based on biodegradable polymers containing oxamyl against the potato cyst nematode is illustrated by examples.

Example 1. Study of nematicidal activity in a vegetative experiment on the potato variety "Pushkinets". Potato plants were grown in 0.5 l containers for 2 months. Field soil was used as a substrate. PKL/MMT granules 50% with oxamil and the commercial drug Vidat® 5G were added to the experimental groups, nothing was added to the control group. The level of introduced invasion of nematode cysts was 50 cysts per plant. The viability of eggs and larvae was 95%. The nematicidal effect was assessed by the number of eggs and larvae and the multiplication factor at the end of the experimental point. The multiplication factor was calculated as the ratio of the final number of nematodes to the initial number. The experiment was carried out in 5 repetitions for each experimental group and control. The results of the experiment are presented in table 2.

Analysis of the results of Table. 2 made it possible to establish that the developed PKL/MMT 50% granules with oxamil have a negative effect on the development of the potato nematode. In the experimental group 1, the lowest multiplication factor was registered (3.5 times lower compared to the control), which is higher/comparable to the commercial drug.

Example 2. Study of the nematicidal effect of PKL/MMT granules with oxamyl in a vegetative experiment on a susceptible potato variety "Krasnoyarsky early" in a laboratory soil microecosystem. Potato plants were grown in 0.5 l containers for 3 months. Field soil was used as a substrate. PKL/MMT granules 50% with oxamyl (conc. oxamyl 50 g/kg) and commercial drug Vidat® 5G (28 mg) were added to the experimental groups, nothing was added to the control group. The level of introduced invasion of nematode cysts will be 50 cysts per plant. The viability of eggs and larvae was 95%. The nematicidal effect was assessed by the number of eggs and larvae and the multiplication factor at the end of the experimental point. During the growing season, the following indicators were measured: plant height, number of stems, weight of green biomass, weight of the root system, weight of tubers. The results of the experience are presented in table 3.

Analysis of the data in Table 3 showed that the introduction of a granulated ecological form can reduce the number of nematodes by 3.8 times, which affects the development of plants. In the experimental groups, an increase in plant height, weight of green biomass and weight of tubers by 1.15-1.2 times was noted compared to the control. In the group with the addition of PKL/MMT+oxamil granules, the indicators of potatoes significantly exceed those in the group with Vidat® 5G. Thus, we can say that the developed granules have a long-term nematicidal effect.

Claims (3)

1. A long-acting biocidal agent for soil use containing a systemic preparation and a biodegradable material, characterized in that a nematocide-insecticide from the group of carbamates is used as a systemic preparation, and polycaprolactone mixed with organomodified clay is used as a biodegradable material in the following ratio of components, weight.%: insecticide nematocide 10-20 polycaprolactone 40-75 organic-modified clay 5-50 2. A biocidal agent according to claim 1, characterized in that oxamyl ((EZ)-N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)acetamide), or thiodicarb, or carbaryl is used as a nematocide-insecticide of the carbamate group , or propoxur.