Devices containing plant-active ingredients applied to the soil or aerial parts of plants

Abstract

The present invention relates to a controlled-release formulation comprising a biocompatible and biodegradable copolyester obtainable by the polycondensation of a diacid and a polyol, and a phytosanitary active ingredient and / or a biostimulant and a plant treatment method comprising the application to at least part of the plants or to the soil of a formulation according to the invention.

Description

Title of the invention: Devices containing plant-active ingredients applied to the soil or aerial parts of plants FIELD OF INVENTION

[0001] The field of the present invention is that of devices containing active ingredients for plants applied to the soil or aerial parts (foliage system or trunk) such as stimulants, fertilizers, pesticides, fungicides or nutrients.

[0002] The improper use of these products in liquid or solid form causes adverse effects on plants, environmental contamination, a decrease in soil fertility and harm to non-target organisms due to runoff, leaching or volatilization processes.

[0003] Reducing fertilizer consumption is an important focus, combined with reasoned and targeted use on the plants in question. Finding effective strategies for the controlled release of active molecules onto plants, with appropriate formulation, is therefore a major concern in order to limit environmental impacts (contamination, soil fertility, climate change (less NOx (N2O and NO) release)) while optimizing expenditure on bioactive molecules (cost reduction) and improving yields and commercial potential.

[0004] Among the many controlled-release systems for plant-active ingredients (Trenkel, ME, Slow- and Controlled-Release and Stabilized Fertilizers: An Option for Enhancing Nutrient Use Efficiency in Agriculture, Second Edition, IFA, Paris, 2010), polymer-coated fertilizers can be cited. However, this type of fertilizer is known for release problems; indeed, generally 15 to 30% of the coated fertilizer is not released due to the presence of concentration gradients within the polymer. Systems based on degradable polymers have therefore been developed. However, many problems remain, such as the toxicity of the degradation products, the rate of degradation, and the complexity of the systems developed using polymer mixtures (Majeed et al., Rev. Chem. Eng. 2015, 31(1), 69-95). Fertilizers using nutrient nanoparticles have also been considered (Gomes, DG et al., Advances in Nano-Iron-tilizers and Nano-Pesticides in Agriculture, Woodhead Publishing, 2021, chap. 5, Pages 111-143). .

[0005] As active products with respect to plants, one can also mention in particular plant stimulants for agricultural application, in particular Rubber trees, such as Hevea brasiliensis.

[0006] Latex from rubber trees, such as Hevea brasiliensis, is produced by the tree's bark, particularly the laticiferous vessels. Incisions in the bark, a process called tapping, allow the latex to ooze out, enabling its collection and use as a raw material for the production of natural rubber. This natural rubber is then processed for use in rubber product formulations, particularly tires. The quantity of latex harvested depends on the frequency of tapping, the tree's latex production rate, and the tree's latex regeneration rate. The tree's health, which determines the quality of the bark and therefore the quality and quantity of latex produced, is thus crucial.

[0007] Consequently, a key concern is to achieve sustainable exploitation of rubber trees in order to ensure the long-term viability of the plantations by limiting the stress on the trees caused by tapping, while guaranteeing the preservation of biodiversity and the local populations who depend on this crop. Reducing the frequency of tapping is now a widely adopted practice, which nevertheless leads to a decrease in latex yield. To compensate for this yield reduction, chemical stimulants are applied. The best known and most widely used is an ethylene generator, 2-chloroethylphosphonic acid, known as Ethephon (2-chloroethylphosphonic acid), which can be found, for example, under the name Ethrel® (Bayer), formulated as an aqueous solution. STATE OF THE ART

[0008] Documents GB1281524 (1972), GB1320870 (1973), US4144046 (1974), GB1498948 (1978), and BR7506379 (1975) describe aqueous liquid formulations containing ethephon and optionally additives (palm oil, ethanol, propylene glycol, acetic anhydride, fatty alcohols, etc.) acting as stabilizers. These solutions, generally applied with a brush to the bark of rubber tree trunks, particularly in the tapping zone (below or above), allow for significant gains in latex yield of 22% (document GB 1281524 (1972)) to 64% (document GB1498948 (1978)) over a 12-month period compared to the controls.

[0009] GB 1320870 (1973) more precisely describes a composition containing approximately 12% of ethephon, 0.08% thickener, 1.6% ethanol, 75% water, and palm oil (10%), while BR7506379 (1975) describes a formula composed of 10% ethephon and 90% of a mixture of almond oil, fat, propylene glycol, and acetic anhydride. The majority of existing formulations applied to trees consist of diluting concentrated commercial ethephon solutions in water to concentrations in the range of [percentage missing].

[0010] It is also known that to obtain optimum latex yields, the stimulation frequency and stimulant concentration must be modulated according to the time of year, variety and age of the tree and the tapping process.

[0011] Ethephon solutions to be applied to the trunks of Hevea trees suffer from several disadvantages, both in terms of implementation and the effect on the trees.

[0012] It is necessary to dilute commercially available concentrated ethephon solutions in water before brush application to the tree. This dilution must be carried out on-site just before application to limit premature degradation of the stimulant in a diluted environment, which exposes operators to the toxicity and corrosiveness of the product. Controlling the amount of product applied to the bark is also difficult with brush or spray application techniques, which also results in product loss to the environment. Finally, existing solutions do not allow for controlled release of the active ingredient over time within the tree, but rather through acute stimulation over a short period. Consequently, the effective annual stimulation period for the trees is short, requiring very regular stimulant application throughout the year (estimated at approximately twenty times per year).Furthermore, the very humid and rainy climate in tropical and intertropical regions regularly leaches leachate from the tree trunks, resulting in losses of the stimulant solution into the environment. This leads to a reduced stimulation effect and contamination of the surrounding environment. The long-term impacts of the toxic and corrosive chemicals in ethephon solutions on the surrounding nature, the local ecosystem, users, and local residents should not be overlooked. Description of the invention

[0013] The applicant has developed a formulation comprising, on the one hand, a bio-based, biodegradable, biocompatible polymer exhibiting some antimicrobial activity, and on the other hand, a stimulant, in particular ethephon. The material used is poly(glycerol sebacate), or PGS. The PGS material is harmless to the tree and the environment. This formulation contains a precise concentration of ethephon and allows for the targeted application of a defined quantity of stimulant to the tree, limiting losses to the environment due to application techniques and climatic conditions. This formulation also allows for controlled release of the stimulant over time, ensuring continuous and regular stimulation throughout the year, which significantly reduces not only the frequency of tapping but also the frequency of stimulation.Finally, controlled release allows continuous stimulation of rubber trees throughout the year, resulting in a significant gain in productivity of plots compared to plots stimulated with the . existing aqueous solutions. DESCRIPTION OF THE FIGURES

[0014] [Fig. 1] Photographs taken during the test of example 1 (a. Composition after 5 days, b. Composition after 90 days)

[0015] [Fig.2] Photographs taken during the test of example 1 (a. Untreated shrub, b. Shrub treated with 2 g of the composition)

[0016] [Fig.3] SEC chromatograms on formulation samples taken during the test

[0017] Gly = free glycerol, AS = Sebacic Acid. The dimers and trimers are oligomers of sebacic acid and glycerol, formed respectively of a chain of 2 and 3 monomeric units. DEFINITIONS

[0018] The term “biocompatible” means: that which is tolerated by the organism, here in particular that which is tolerated by plants.

[0019] The term “biodegradable” means: capable of being broken down by living organisms.

[0020] For the purposes of the present invention, "biodegradable copolyester" means a copolyester that is biodegradable under the growing conditions, particularly temperature and humidity, of the plants whose treatment falls within the scope of the present invention. Preferably, and under these conditions, "biodegradable copolyester" means a copolyester that is more than 80% biodegradable within one year.

[0021] Preferably, for the purposes of the present invention, "biodegradable copolyester" means a biodegradable copolyester according to standard EN 13432.

[0022] A plant protection product, plant protection product or phytopharmaceutical product, is a substance or mixture of substances of a chemical or biological nature (of natural or synthetic origin) used in agriculture, horticulture or forestry to protect cultivated plants against bioaggressors (animal pests, phytopathogenic agents, parasitic plants, weedy plants) or to optimize crops by promoting the growth of cultivated plants and by treating their environment (in particular the soils).

[0023] The term “biostimulant” means a substance which stimulates plant nutrition processes independently of the nutrients it contains with the aim of improving one or more of the following characteristics of plants or their rhizosphere: nutrient use efficiency, tolerance to abiotic stress, qualitative characteristics, availability of nutrients confined in the soil or rhizosphere (in accordance with EU Regulation 2019 / 1009).

[0024] Biostimulants may be certain low-risk natural preparations (PNPP). The PNPPs are:

[0025] - Either natural substances for biostimulant use (SNUB).

[0026] - Either basic substances.

[0027] Basic substances are defined by Article 23 of Regulation (EC) 1107 / 2009. They are substances of phytosanitary interest but whose main use is other than plant protection (for example, foodstuffs). DETAILED DESCRIPTION OF THE INVENTION

[0028] The invention relates to a controlled-release formulation comprising a biocompatible and biodegradable copolyester obtainable by the polycondensation of a diacid and a polyol, and a phytosanitary active ingredient and / or a biostimulant. Copolyesters

[0029] The formulation according to the invention comprises a biocompatible and biodegradable copolyester that can be obtained by the polycondensation of a diacid and a polyol.

[0030] For the purposes of this invention, the term "polyol" means an organic molecule comprising at least two alcohol functions.

[0031] The copolyesters according to the invention are polyesters composed of at least two different diacid and polyol motifs.

[0032] According to a preferred embodiment, the diacid is chosen from aliphatic carboxylic diacids, preferably (C3-C2o)alkyldiacids, more preferably (C8-Ci5)alkyldiacids.

[0033] The diacids are preferably chosen from among the diacids having two terminal carboxylic acid functions.

[0034] Preferably, the diacid is sebacic acid.

[0035] [Chem.l]

[0036] According to a preferred embodiment, the polyol is chosen from among the diols and triols, preferably from among the triols, preferably the polyol is glycerol.

[0037] [Chem.2] OH HO^A^OH

[0038] The biocompatible and biodegradable copolyester is advantageously poly(glycerol sebacate) (PGS) and its derivatives, more preferably poly(glycerol sebacate) with the general formula below.

[0039] [Chem.3]

[0040] The ratio of polyol monomer to diacid monomer is advantageously between 0.3:1 and 1:0.3.

[0041] Poly(glycerol sebacate) can be obtained by means of a two-step synthesis: a first esterification step and a second polycondensation step, and optionally a third crosslinking step. The first step consists of an esterification reaction between an acid group of sebacic acid and an alcohol group of glycerol. Terminal alcohol groups react preferentially. The second step consists of growing the chains to obtain a PGS resin.

[0042] Subsequently, various strategies can be used to adjust the properties of the polymer, such as long thermal crosslinking by esterification of the dangling secondary alcohol functions (often at high temperature and low pressure), or crosslinking via post-functionalization (such as functionalization of the polymer matrix, for example with acrylate or methacrylate functions, followed by radical crosslinking or crosslinking with isocyanates, such as hexamethylenediamine diisocyanate). It is also possible to copolymerize PGS with blocks of other linear polymers, for example with polylactic acid (PLA), poly(lactic-co-glycolic) (PLGA), polycaprolactone (PCL), or poly(butyl succinate) (PBS).

[0043] For the purposes of the present invention, all of these compounds are grouped under the name poly(glycerol sebacate) and its derivatives.

[0044] Preferably, the biocompatible and biodegradable copolyester is bio-based. In this case, it can be obtained from renewable raw materials derived from biomass.

[0045] The formulation according to the invention advantageously comprises 1% to 99% by weight, preferably 2% to 98% by weight, preferably still 3% to 96%, particularly preferably 5% to 95% by weight, of a biocompatible and biodegradable copolyester that can be obtained by the polycondensation of a diacid and a polyol.

[0046] In one embodiment of the invention, the biocompatible and biodegradable copolyester is in elastomeric form, i.e. which exhibits elastic properties after crosslinking.

[0047] In one embodiment of the invention, the formulation advantageously comprises residual monomers that have not been incorporated into the chains of the biocompatible and biodegradable copolyester (diacid and / or polyol), at levels < 90% by weight, preferably < 80% by weight, and more preferably < 70% by weight. Plant protection products

[0048] Preferably, the formulation according to the invention comprises a phytosanitary active ingredient and / or a biostimulant selected from the group consisting of stimulants, fertilizers, pesticides, fungicides, nutrients, bactericides, insecticides, growth regulators.

[0049] Preferably, the formulation according to the invention comprises a phytosanitary active ingredient and / or a biostimulant which is a precursor of ethylene, preferably ethephon.

[0050] Advantageously, the formulation according to the invention relates to a formulation in which the biocompatible and biodegradable copolyester is poly(glycerol sebacate) (PGS) and the phytosanitary active ingredient and / or biostimulant is ethephon.

[0051] The formulation according to the invention advantageously comprises from 1% to 99% by weight, preferably from 2% to 98% by weight, particularly preferably from 5% to 95% by weight, of a phytosanitary active ingredient and / or a biostimulant.

[0052] The formulation according to the invention advantageously comprises 5% to 95% by weight of ethephon.

[0053] The formulation according to the invention advantageously comprises from 0.1% to 99% by weight, preferably from 0.5% to 95% by weight, particularly preferably 1% to 90% by weight of water. Additives

[0054] The formulation according to the invention may include one or more additives selected from the group consisting of stabilizers, compatibilizing agents, shaping agents, active ingredient release regulators, and antioxidants.

[0055] The formulation according to the invention can be in the form of a paste, patch, granules or propellant solution, preferably in the form of a paste.

[0056] When the formulation according to the present invention is in the form of a paste, the formulation according to the invention advantageously comprises 20% to 80% by weight, preferably 30% to 70% by weight, preferably still 40% to 70% by weight of a biocompatible and biodegradable copolyester that can be obtained by the polycondensation of a diacid and a polyol.

[0057] When the formulation according to the present invention is in the form of a propellant solution, the formulation according to the invention advantageously comprises 1% 50% by weight, preferably 2% to 40% by weight, preferably still 3% to 30% by weight of a biocompatible and biodegradable copolyester that can be obtained by the polycondensation of a diacid and a polyol.

[0058] When the formulation according to the present invention is in the form of granules, the formulation according to the invention advantageously comprises 50% to 99% by weight, preferably 60% to 98% by weight, preferably still 70% to 97% of a biocompatible and biodegradable copolyester that can be obtained by the polycondensation of a diacid and a polyol.

[0059] When the formulation according to the present invention is in the form of a paste, it advantageously comprises from 1% to 50% by weight, preferably from 2% to 40% by weight, particularly preferably 3% to 30% by weight of water.

[0060] When the formulation according to the present invention is in the form of a solution to be propelled, it advantageously comprises from 50% to 99% by weight, preferably from 60% to 98% by weight, particularly preferably from 70% to 97% by weight of water.

[0061] When the formulation according to the present invention is in the form of granules, it advantageously comprises from 0.1% to 30% by weight, preferably from 0.2% to 20% by weight, particularly preferably from 0.3% to 10% by weight of water. Preparation process

[0062] Various methods of formulating the copolyester with the plant protection active ingredient and / or the stimulating biostimulant may be used. Examples include, but are not limited to, a mixture of molten copolyester with the plant protection active ingredient and / or the biostimulant in solution, for example in aqueous solution.

[0063] This mixture can be prepared in a conventional stirred reactor at relatively mild temperatures to limit the risk of degradation of the active ingredient of the plant protection product and / or the biostimulant, preferably <120°C, preferably <110°C, preferably <100°C, using conventional agitators or ultraturax shear agitators, while limiting the contact time. The mixing process can be batch, semi-batch, or continuous. Application method

[0064] According to one embodiment, the formulation according to the invention is intended to be applied to the trunk of shrubs and trees, in particular when it is in the form of a paste, patch or solution to be propelled.

[0065] Another object of the invention relates to a plant treatment method comprising applying to at least one part of the plants, preferably one or more aerial part(s), or to the soil, a formulation according to the invention.

[0066] When the formulation according to the present invention is in the form of a paste, a patch or a propellant solution, it is preferably applied to at least one part of the plants, preferably one or more aerial part(s).

[0067] According to one embodiment, the plant treatment process according to the invention relates to trees or shrubs and the formulation is applied to the trunk.

[0068] The trees or shrubs are preferably chosen from the group consisting of rubber trees, vines, olive trees, fruit trees and ornamental plants, preferably rubber trees.

[0069] When the formulation according to the present invention is in the form of a paste, it is preferably sticky and can be spread with a spatula or with a sealant gun type application device, allowing a controlled mass to be applied to the plant.

[0070] A device consisting of a "hard" layer in contact with a "sticky" layer of the type of pre-cut patch of suitable dimensions can also be envisaged. It can be fixed to one or more aerial part(s) of the plant, for example on the trunk or for example on the leaves or the fruit.

[0071] When the formulation according to the present invention is in the form of granules, it will be applied to the ground.

[0072] The following examples illustrate the invention without limiting its scope. Examples

[0073] Method of analysis by size exclusion chromatography (SEC)

[0074] The PGS samples were solubilized to a concentration of approximately 1.5 gL 1 in THF, then stirred for 2 hours before being injected.

[0075] The analytical conditions used are described in the table below:

[0076] [Tables 1] THF eluent, injection volume 100 pL, concentration ~ 1.5 g / L, temperature 35 °C, RI Waters detector, mobile phase flow rate 1 mL / min, columns 2 Mixed D + 2 Mixed E, calibration polystyrene (PS)

[0077] The analyzable mass range is between 162 g / mol and 7,500,000 g / mol. The number-average molecular mass (Mn) is expressed in g / mol as PS equivalent. Similarly, the average molecular mass by weight (Mw) is expressed in g / mol as PS equivalent. The dispersity D is defined by the relation Mw / Mn.

[0078] Method for measuring free ethephon in the composition

[0079] Free ethephon is analyzed by 13C NMR. A Bruker AVANCE III 500 MHz spectrometer equipped with a 5 mm z-gradient BBFO cryogenic probe allows the acquisition of samples solvated in acetone-d6 with calibration at 29.9 ppm. The signals of free ethephon are measured at 38.2 ppm (C1CH2, s), and at 31.7 ppm (CH2P, d, 'J = 133 Hz).

[0080] All monomers (glycerol (99.5%) and sebacic acid (99%)) and the stimulant (ethephon) are commercially available and were used without further purification. The ethephon solution used is a concentrated aqueous commercial solution (Ethrel®) with an ethephon concentration of approximately 480 g / L, or about 42% by mass of ethephon.

[0081] EXAMPLE 1: Aging test of the formulation according to the invention without principle active on rubber trees (Hevea brasiliensis)

[0082] Summary of the PGS:

[0083] A sample of PGS was prepared by mixing 3 molar equivalents of glycerol (230 g) with 1 molar equivalent of sebacic acid (169 g) and water (72 g) in a 500 mL reactor fitted with a distillation column and a condenser connected to a distillate receiver. The mixture was heated to 130°C for 24 h at atmospheric pressure under an inert atmosphere (N2), and the water was collected in the distillate receiver. The mixture was then heated under vacuum (5 mbar) at the same temperature for one hour. The resulting PGS has the following characteristics: Mn = 860 g / mol, Mw = 1020 g / mol, D = 1.2.

[0084] Formulation and implementation of a composition without an active ingredient on Hevea tree trunk:

[0085] The resulting PGS is either used as is or mixed with water in a stirred reactor at 30°C for 15 min. Preparations with water contents of 0.1% and 5% were thus obtained. The composition is in the form of a paste at room temperature. Approximately 2 g of the composition were then applied to the trunk of a Hevea tree using a spatula in a representative environment (temperature, humidity, watering).

[0086] Composition aging test:

[0087] Monitoring of a composition without additional water was carried out over 3 months with photographs taken, samples and analyses by size exclusion chromatography (SEC) to verify the evolution of the material under real conditions and its biodegradability.

[0088] As can be seen in the photographs in [Fig. 1], a significant evolution is noted fictional change in the appearance of the patch between 90 days and 5 days of testing, with the disappearance of a significant amount of material.

[0089] As seen in the superposition of SEC chromatograms ([Fig. 3]) from three samples taken at t = 0 days (initial state), 14 days, and 107 days, a significant decrease in the free glycerol level, the appearance of sebacic acid, and a decrease in the signals of the dimeric and trimer oligomers are observed, confirming hydrolysis (and leaching) of the copolyester. In conclusion, the coating remains intact after 3 months, associated with a biodegradation phenomenon.

[0090] EXAMPLE 2: Stimulation test of calamondins (Citrus microcarpa) with a formulation according to the invention comprising ethephon

[0091] Summary of the PGS:

[0092] A sample of PGS was prepared by mixing 3 molar equivalents of glycerol (230 g) with 1 molar equivalent of sebacic acid (169 g) and water (72 g) in a 500 mL reactor fitted with a distillation column and a condenser connected to a distillate receiver. The mixture was heated to 130°C for 24 h at atmospheric pressure under an inert atmosphere (N2), and the water was collected in the distillate receiver. The mixture was then heated under vacuum (5 mbar) at the same temperature for one hour. The resulting PGS has the following characteristics: Mn = 860 g / mol, Mw = 1020 g / mol, D = 1.2.

[0093] Formulation of the composition:

[0094] The PGS obtained (9.1 g) is placed in a reactor heated to 30 °C for 15 min with stirring. An aqueous solution of ethephon concentrated at 480 g / L, i.e., 42 wt% ethephon, is added dropwise to the mixture (1.9 mL, i.e., 0.9 g ethephon). The mixture is stirred for an additional 5 minutes to obtain a homogeneous paste containing 8 wt% ethephon, 11 wt% water, and 81 wt% PGS.

[0095] Application of the composition to the plant:

[0096] The composition is finally applied in different quantities to the trunks of the calamondins bearing green fruits with a spatula (2 g, i.e. about 160 mg of ethephon and 5 g, i.e. about 400 mg of ethephon).

[0097] Two test pieces were made:

[0098] Control 1 = shrub without treatment, Control 2 = above composition deposited on an inert surface (aluminum plate). Goals :

[0099] - Note a stimulation of fruit ripening - Take samples over time to measure the ethephon level in the paste - Monitoring of plant stimulation activity Results :

[0100] As seen in [Fig.2], after 15 days: - Untreated shrub (control 1): no significant change - Shrub treated with 2 g: all fruits are orange (ripe)

[0101] The ethephon content decreases significantly after 15 days in the paste applied to the shrubs (decrease in concentration of more than 80%), much less in Control 2 (composition deposited on inert surface, with a decrease in ethephon concentration of less than 50%).

Claims

Demands

1. Controlled-release formulation, in paste form, intended to be applied to the trunk of shrubs and trees comprising poly(glycerol sebacate) (PGS) and a phytosanitary active ingredient and / or a biostimulant.

2. Formulation according to claim 1, wherein the active phytosanitary and / or biostimulant principle is selected from the group consisting of stimulants, fertilizers, pesticides, fungicides and nutrients.

3. Formulation according to claim 2, wherein the phytosanitary and / or biostimulant active ingredient is ethephon.

4. Formulation according to any one of the preceding claims comprising one or more additives selected from the group consisting of stabilizers, compatibilizing agents, shaping agents, active ingredient release regulators, antioxidants.

5. Formulation according to any one of the preceding claims comprising 1% to 99% by weight of poly(glycerol sebacate).

6. Formulation according to any one of the preceding claims comprising from 1% to 99% by weight, preferably from 2% to 98% by weight, of a plant protection active ingredient and / or a biostimulant.

7. Formulation according to claim 6 comprising 5% to 95% by weight of ethephon.

8. Formulation according to any one of the preceding claims comprising from 0.1% to 99% by weight of water, preferably from 0.5% to 95% by weight, particularly preferably 1% to 90% by weight of water.

9. A method for treating shrubs or trees comprising applying to at least part of their trunk a formulation according to any one of the preceding claims.

10. A method for treating shrubs or trees according to claim 9, wherein the shrubs or trees are selected from the group consisting of rubber trees, vines, olive trees, fruit trees and ornamental plants, preferably rubber trees.

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