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Reducing the pesticide burden on UK crops through the use of targeted delivery systems - LK0987

The purpose of this proposal is to make available enabling technology for the commercial development of a new spray technology based on the use of charged electret inclusions developed by Exosect Ltd. Electrets are materials that maintain a permanent dielectric polarisation, or bulk charge, rather than a surface electrostatic charge. The purpose of the charged particle is to enhance adherence to both foliage and the target pest. Recent research by Law & Scherm (2005) demonstrated that the electrostatic spray delivery of the viable bacterial biocontrol agent, Bacillus subtillus, to blueberry flowers were enhanced 4.5 fold over conventional hydraulic spraying. Of considerable interest was the improvement of adhesion to difficult-to-target stigmatic surfaces of the flower, which is a common route for floral infection. Although the electret technique is not aiming to charge the entire droplet as Law and Scherm (2005) have done, this research is relevant in that it is a particulate being sprayed which is demonstrating enhanced electrostatic deposition to a complex structure.

Previous research looking at electrostatic charging of the actual spray droplets resulted in technologies such as the Electrodyn hand-held sprayer. Although this technology resulted in increased deposition of active ingredient onto the crop, there were tight constraints over the formulations that would adequately charge droplets to a sufficient level. The inflexibility of the formulation meant that only certain active ingredients could be used with Electrodyn, which eventually made it an unviable commercial product. In this proposal the incorporation of active ingredient within the electret inclusions, thus largely isolated from the oil or water formulation, has potential for a far more flexible formulation than was previously possible with induction or tribo-charged based systems.

This project aims to evaluate whether or not electrets can be applied directly to foliage by spraying, in either a water or oil-based low volume spray. If it can be demonstrated that the electrets may be sprayed using a viable formulation and spray applicator, the project will assess the potential of developing this technology for a novel lure and kill system. The project utilises the expertise of IPARC as a pesticide application specialist, Exosect Ltd. as developer of electrostatic particulate technology, Micron Sprayers Ltd. as experts in the manufacture and design of application equipment and DOW Agrosciences as providers and analytical capabilities for active ingredients. If successful, this novel technology may improve efficacy whilst at the same time reducing spray drift and pesticide application rates (as a lure and kill spray would be delivered at point sources throughout the crop), lengthen required spray intervals, minimise the pesticide burden in the environment and exposure risk to operators.

This proposal aims to examine whether Exosect’s electret powders may be sprayed by a farmer using traditional spray equipment. The deposition of powders on a plant (barley seedlings) will be evaluated as will the longevity of the powder adherence to the plant surface. If the proof-of-principle experiments are successful Exosect’s pheromone technology could ultimately be combined with a formulation of active ingredients in electrostatic powders to create a ‘low-dose’, ‘lure and kill’ application, which would be tank-mix applied using normal spraying practices and equipment. As lure and kill is not a blanket application approach, the farmer will not need to uniformly spray the entire crop, which means less time needed for an application, less soil compaction from repeated tractor runs and ultimately less cost and less water usage.

This project will bridge the knowledge gap between current understanding of electrostatic electret systems in powder formulations and their potential for use as targeted sprayable delivery systems for widespread use in agriculture.

There are a number of important drivers for the development of enhanced spray delivery techniques (see Section 7 – benefits to industry, science and the environment), the most important of which is the Government’s drive for a Sustainable Pesticide Policy. The knowledge gaps (KG) are;

· Understanding of the feasibility to infuse electrets with synthetic active ingredients in a spray mix? (KG1).
· Determining the effect that water will have when mixing electret charged powders with active ingredients (KG2).
· Identifying how tank mixed electrets will be distributed when sprayed in the field and how the type of machinery and nozzle affect the solid inclusions spray system (KG3).
· Understanding the longevity of sprayed electret particulates in terms of plant folliage adherence and active ingredient persistence (KG4)

In this context, this project is designed to further develop our understanding of how the powders will behave when mixed into a liquid, what are the physical constraints on spraying an electret powder and does an electret powder offer a long-lasting adhesion to plant material whilst the active ingredient is still retaining biological activity.
This is a science-based project utilising the knowledge and resources of world-experts at the International Pesticide Application Research Centre, Imperial College, UK.

Specific objectives to achieve these aims in response to the knowledge gaps (KG) identified above are;

· Objective 1: To test the feasibility of including synthetic active ingredients infused into electrets in a spray mix (KG1).
· Objective 2: Assessing the formulation of water-mixed electrets and identifying best nozzle types for a solid inclusions spray system (KG2, KG3).
· Objective 3: Undertake a small scale foliage trial to examine the adherence of powders to plant material and the effects of weathering on powder retention and active ingredient longevity (KG4).

As an SME, Exosect will operate as the principal industrial partner in this project, with the aim of developing and licensing resultant IPR for use in UK and eventually worldwide agriculture.
Time-Scale and Cost
From: 2006

To: 2008

Cost: £38,140
Contractor / Funded Organisations
Fahrenheit Holding B.V. Amsterdam, Micron Sprayers Ltd, Imperial College Consultants Ltd (IC Consultants Ltd), Exosect
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Sustainable Farming Systems