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EP-3897155-B1 - ENCAPSULATED PESTICIDE

EP3897155B1EP 3897155 B1EP3897155 B1EP 3897155B1EP-3897155-B1

Inventors

  • HAIGH, Graham

Dates

Publication Date
20260506
Application Date
20191220

Claims (15)

  1. A method for encapsulating a pesticide, including the steps of (a) mixing, in solution, a first biopolymer which is an alginate with a viscosity from 4 to 100 centipoise measured for 1% aqueous solution at 20 centigrade (°C) and a second biopolymer which is a pectin, (b) adding the product of step (a) to a solution of pesticide, (c) adding calcium ions and adding a surfactant to the product of step (b), wherein the method is carried out in an aqueous solution.
  2. A method as claimed in claim 1, wherein the pectin is in the form of an ester.
  3. A method as claimed in claim 1 or 2, wherein the ratio of the first to the second biopolymer is from 9:1 to 1:9.
  4. A method as claimed in claim 3, wherein the ratio of the first to the second biopolymer is about 3:1.
  5. A method as claimed in any preceding claim, wherein in step (b) the product is stirred at a rate of stirring from 500 to 3000 RPM.
  6. A method as claimed in claim 5, wherein the product is continuously stirred from 30 minutes to 24 hours.
  7. A method as claimed in any preceding claim, wherein the pesticide is glyphosate, glufosinate, or any water-soluble pesticide.
  8. A method as claimed in claim 7, wherein the pesticide is glyphosate in the form of a salt of ammonium, diammonium, dimethylammonium, isopropylammonium, potassium or sesquisodium.
  9. A method as claimed in any preceding claim, wherein step (b) is carried out at a temperature from 40°C to 60°C.
  10. A method as claimed in any preceding claim, wherein the pesticide is provided in the form of a 62% solution in water.
  11. A method as claimed in any preceding claim which is carried out as a continuous process or as a batch process.
  12. A method as claimed in any preceding claim in which the amount of pesticide in the final product is from 0.2 w/v % to 40 w/v %.
  13. A method of applying an encapsulated pesticide comprising: i) obtaining the encapsulated pesticide by the method as claimed in any preceding claim and ii) applying the product together with an adjuvant to a plant.
  14. A method as claimed in claim 13, wherein the adjuvant is PBO.
  15. A method of applying an encapsulated pesticide comprising: i) obtaining the encapsulated pesticide by the method as claimed in any of claims 1 to 12 and ii) applying the product in the absence of an adjuvant to a plant.

Description

The present invention relates to a method for encapsulating a pesticide, and in particular to a method which avoids the need for forming an emulsion. It also relates to an encapsulated pesticide formed according to the method, and to methods of using the pesticide with or without an adjuvant. More particularly it relates to a pesticide which is a herbicide. Herbicides are commonly used in agriculture to improve the productivity and quality of the grown product. The global market for herbicides is estimated to reach $31.5 billion by 2020. Asia-Pacific is the dominant market accounting for two fifth of herbicide use, whereas North America region equates to one-third of global revenue generated by the herbicide market. At present, the most widely used herbicide in the world is glyphosate, which has global sales amounting to more than $10 billion per year due to low cost production and low environmental impact. As a result of the prolonged use of herbicides, weeds are becoming resistant and this is increasing exponentially with over 217 weed species presently resistant around the world. In most cases, it is estimated that weed resistance will emerge within three years on a piece of land which has been treated with a given herbicide. Current solutions are either to develop novel herbicides or switch from glyphosate-ready to glufosinate-ready crops. Both alternatives are expensive and there are no guarantees that the weed will not become resistant after 3-5 years. In case of the herbicide glufosinate, weed-resistance has already been reported. The first cases of weed-resistance were reported in 2009 and increasing use of the herbicide is likely to result in widespread resistance. Other alternatives are to use higher dosages of glyphosate, which could be detrimental to the environment or in extreme circumstances manual removal of the weeds, which is labour intensive. Both alternatives lead to higher costs or danger of ruining the fertile land. EP 1 499 183 B2 (Rothamsted Research Institute Limited et al.) discloses a method for preventing or reducing resistance to a pesticide of a substrate pest, which method comprises administering to the substrate or the pest a metabolic enzyme inhibitor (such as piperonyl butoxide - PBO) and (substantially simultaneously) a pesticide (such as a pyrethroid insecticide) encapsulated in a degradable capsule. The capsule prevents an effective dose of the pesticide from being absorbed by the pest until the inhibitor has had time to begin its inhibiting effect on the substrate. The formulation used in this case is Karate Zeon® which is a PVA-encapsulated insecticide (lambda-cyhalothrin) produced by Syngenta. EP 0427991 A1 (Sumitomo Chemical Co.) discloses an insecticidal and/or acaricidal and/or nematicidal composition which is a mixture of an encapsulated part which is formed of water-insoluble microcapsules and a flowable part which is emulsified or suspended in water. US 2015/320036 A1 discloses a process for obtaining biopolymeric nanoparticles containing Azadirachta indica A. Juss (Neem), which comprises, in Phase I, preparing an aqueous emulsion of Neem oil and extracts, in Phase II, preparing a biopolymer solution in organic solvent, followed by mixture of both Phases I and II, and, in Phase III, preparing an aqueous emulsion of a surfactant and adding it to the Phase I and II mixture, affording a nanoparticle suspension which is stabilized. Biopolymeric nanoparticles and powder microparticles obtained are also described. US 2016/0330952 A1 discloses methods for the encapsulation of volatile organic compounds by formation of stable emulsions of the volatile organic compounds that are mixed with encapsulating polymer solutions and then formed into ultrafine fibers. The ultrafine fibers containing the encapsulated volatile organic compounds can be formed into a variety of formats for use to preserve perishable products. The present applicant has filed International Patent Publication No. WO 2019/008341 which seeks to provide an improved encapsulated pesticide. The present application seeks to provide yet a further improvement, and in particular an improved method which is commercially suitable for industrial production of the encapsulated pesticide. Other prior art documents include: GERSTL Z ET AL, "Controlled release of pesticides into water from clay -polymer formulations", JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, AMERICAN CHEMICAL SOCIETY, BOOKS AND JOURNALS DIVISION, US, (19980901), vol. 46, doi:10.LOCATELLI GABRIEL OLIVO ET AL, "Development ofTrichodermasp. formulations in encapsulated granules (CG) and evaluation of conidia shelf-life", BIOLOGICAL CONTROL, (20170901), vol. 117, doi:10.1016/J.BIOCONTROL.GERMÃ N A ISLAN ET AL, "Studies of Ciprofloxacin Encapsulation on Alginate/Pectin Matrixes and Its Relationship with Biodisponibility", APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY; PART A: ENZYME ENGINEERING AND BIOTECHNOLOGY, HUMANA PRESS INC, NEW YORK, (20120228), vol. 167,