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Spray behaviour at reduced application volumes - LK0922

Reducing water volume rates below 200l/ha is one of the most valuable methods of increasing work rates, thereby improving timeliness and efficiency of the spray application. There are two limiting factors preventing volumes from being reduced: spray drift and a lack of reliable data concerning the consequences for efficacy.

Spray drift can be overcome by developments in application. However, maintaining efficacy, is more difficult to assess generically since it depends upon a range of factors, including crop canopy, spray liquid, active ingredient, dose rate and application technique.

There may be limits below which volumes cannot be reduced without compromising the quantity retained and/or the distribution of deposits on the target. These limits are likely to depend upon the application equipment and parameters used. The properties of the spray liquid, which will be influenced by the tank mix of formulations and adjuvants, also modify the quantity and distribution of deposit (Holloway et al, 2000). The crop canopy (density, structure and surface) and the target site are also important factors, with target size being potentially crucial.

It is clear that there are too many variables influencing the efficacy of spray application with reducing water volume to be evaluated thoroughly in a single project. There is a substantial amount of relevant work (e.g. Knoche, 1994), but most studies consider only one or two variables over a limited range, and cannot be extrapolated to different application methods, crops or pesticides because the underlying mechanisms are not understood. We need to understand better the interaction between all the variables. It is vital to (a) prioritise variables and concentrate on those that are most important to understand and (b) study only interactions, rather than each variable in detail.

This approach is unlikely to provide all the answers about how to optimise low volume spray application under every set of circumstances. However, it will begin to define the limits to which volume can safely be reduced in some common scenarios, and provide some information about how application techniques, crop structure and spray liquid might influence these limits.

Aims of the project
1 To identify the limits of acceptability for reduced water volume rates and provide scientific justification for their use

2 To provide the necessary information to assist users in determining the most appropriate application techniques to achieve reduced volume rates.
1. To determine how changing application techniques to reduce water volumes affects the characteristics of the spray delivered to the crop.

2. To establish how the distribution of pesticide within crop canopies can be influenced by the interaction between application parameters, crop canopy characteristics and physical properties of the spray liquid.

3. To consider the implications of (1) and (2) for biological efficacy

4. To provide scientifically-based information to allow the acceptable limits to reducing water volumes to be determined.
Project Documents
• Abstract : LK0922 Spray behaviour at reduced application volumes Abstract   (20k)
Time-Scale and Cost
From: 2001

To: 2006

Cost: £117,275
Contractor / Funded Organisations
Lurmark Limited, Arable Research Centres, Crop Protection association UK Ltd, Home Grown Cereals Authority, Cleanacres Machinery, Syngenta, Micron Sprayers Ltd, Billericay Farm Services Ltd, Hardi International, Silsoe Research Institute (BBSRC)
LINK Programme              
Pest and Weed Control              
Pesticide use              
Plants and Animals              
Sustainable Farming and Food              
Fields of Study
Pesticide Safety