Advancing Options for Management and Mitigation of
Spray Drift
Risk Mitigation Measures in Europe to Prevent Plant Protection Product losses to the Environment
Ireland
Risk Mitigation Management and measures
Under the terms of the Common Agricultural Policy (CAP) Single Payment Scheme, a two-meter protection zone must be left around established hedgerows, ditches and watercourses in all fields of two hectares or more. However, you may need to leave a larger buffer zone when you are using certain pesticides (this will be shown on the product label to protect plants and creatures you are not treating, including fish and water). For field crops, you may be able to set up a permanent grass margin to prevent weeds moving to the crop, while providing a habitat for wildlife (including beneficial insects) and protecting hedgerows and watercourses.
In some situations, you may be able to set up a "conservation headland" usually the outermost six meters, to allow grasses and broad-leaved plants to grow and to encourage the insects that live on them. These insects are food for farmland wildlife and birds. Where there are conservation headlands, you should follow agreed management principles to avoid any risk to other plants and animals. The labels of some pesticides will have specific restrictions which you must keep to.
You should take special care when using pesticides on, or near, any land covered by an agri-environment agreement.
The use of buffer zones is now an established drift measure in the UK and there are four schemes that apply in different situations as described below. In some cases, it is possible to reduce the widths of such buffer zones depending on factors such as the applied dose or the application equipment used.
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The Local Environmental Risk Assessment for Pesticides (LERAP) scheme aimed at protecting surface water using a 6.0 m buffer zone (5.0 m measured from the top of the bank). Products are given one of three classifications (A, B, or C) and for LERAP B products it is possible to reduce the width of the buffer zone following a LERAP assessment. The introduction of this scheme involved the setting up a scheme to classify the drift reducing capabilities of application equipment using LERAP star ratings that are used in such assessments. More details of this original scheme are given below.
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The use of 5.0 m buffer zones proved to be restrictive in terms of products that could be registered and so an Interim Scheme was introduced also to protect surface water from exposure to pesticides. Buffer zones are specified on product labels and can be dependent on crop types. Where buffer zones of 5.0 m or less are specified, then these can be reduced following a LERAP assessment as for the original scheme. Buffer zones of 6.0 to 20.0 m specified on product labels cannot be reduced and use a 5.0 m non-cropped zone next to the water course.
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The Drift Reducing Technology Scheme uses drift reducing application systems to allow the use of products that could not otherwise be registered because of their aquatic toxicity. In this scheme, a buffer zone of 6.0, 12.0 or 18.0 m is specified on the label and cannot be reduced. A secondary buffer zone of up to 30 m width is also specified and this can be reduced by using LERAP three-star application equipment.
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The Arthropod scheme aims to protect arthropods and non-target insects and applies to all field boundaries. The widths of the buffer zones are label-specific, can vary with crop type but cannot be reduced. Such buffer zones can be “advisory” or “statutory”.
LERAPs Guide - Horizontal boom sprayers
The LERAP scheme applies only to reducing buffer zones laid down to protect water, they can not be reduced to safeguard hedges, field margins and others.
In short:
- LERAP is only needed when spraying near to a watercourse and if the buffer zone on the label is to be reduced;
- If the watercourse is dry at the time of spraying, a 1-m buffer zone;
- If a 3-star sprayer is used, a 1-meter buffer zone is to be applied;
- If no more than a quarter of the maximum permitted dose rate, a 1-meter buffer zone is to be applied;
- Farmers should consider using a pesticide with no buffer zone requirement, or designating the strip alongside the watercourse as set-aside.
The following chart should be followed to check whether a buffer zone indicated on the product label can be reduced:
The booklet referred to by DEFRA applies to horizontal boom sprayers only. Different rules apply to broadcast air-assisted sprayers. The buffer zone for products applied by hand-held and knapsack sprayers is 1 metre from the top of the bank as long as the nozzle points down and is no more than 0.5 meters above the crop.
The booklet assumes that all necessary planning for the crop, the spray operation and product selection has been done in advance and that requirements of the Green Code are followed throughout. The LERAP scheme applies only to reducing the 5-metre buffer zones laid down to protect water. You cannot reduce buffer zones designed to safeguard hedges, field margins etc. under the LERAP scheme.
Source: DEFRA
Certification and approval procedure for spray drift reducing nozzles
LERAP Low Drift Star Ratings will be awarded to:
- Complete boom spraying systems ('sprayers') designed for operation over arable field crops;
- Nozzles or other spray generation systems ('spray generators') designed for use on boom sprayers.
Star ratings will be awarded by comparing the levels of drift from candidate sprayers or generators with corresponding drift levels from a reference system. this reference system shall be defined as an open structured boom construction fitted with F110/1.2/3.0 nozzles, manufactured from stainless steel, operating with a nozzle height above the target of 0.5 m. The reference sprayer will have the same nozzle specification along the whole length of the boom i.e. no special nozzle design will be used at the end of the boom. The reference sprayer shall be fitted with a boom suspension arrangement to provide isolation from both the rolling and yawing motions of the spray vehicle. Reference performance will be based on spraying of water and of a 0.1% solution of a non-ionic surfactant.
Star ratings will be awarded based on the criteria defined in Table 1 below:
Data requirements
Applications for LERAP Low Drift Star Rating relating to either complete sprayers or spray generators will require submission of a data package that must include:
1. Results from a series of field tests (for complete sprayers and spray generation systems) or wind tunnel measurements (for spray generators) specifically designed to provide data for LERAP Low Drift Star Rating as part of the LERAP scheme; and
2. A collection of existing available information to support appropriate interpretation, extrapolation and interpolation such that drift reduction requirements for a given LERAP Low Drift Star Rating can be implied with a high level of confidence.
Drift reduction evidence from purposely conducted tests t"targeted data")
Complete boom spraying systems (sprayers)
Field tests must be conducted to an adequate defined protocol - see Annex 1 (pdf) or the draft International Standard for the field measurement of spray drift. Results from such tests must report a minimum of:
(i) a profile of the measurable downwind drift deposits between 1 and 12 m from the end of the boom including measurements from samples collected at three separate distances between 2.0 and 6.0 m from the end of the boom using collectors positioned at the top of the target crop/grass/soil surface and designed to collect sedimenting spray drift;
(ii) details of the drift sampling methods used and particularly a description of the collecting surfaces and tracer techniques;
(iii) details of the conditions under which the measurements were made including a mean wind velocity measured at a height of 2.0 m above the ground, a mean air temperature at a height of 2.0 m above the ground and a physical description of the surface under the sprayer and over which the measurements of spray drift were made including the mean heights of vegetative cover;
(iv) data as in (i) and (ii) above for both the candidate sprayer and a system representative of the reference system;
(v) evidence to validate the experimental approaches taken relating to:
- the calibration of the machine prior to conducting the drift trial;
- the calibration of any instrumentation used to monitor the sprayer and weather conditions during a drift trial;
- the recovery and stability of the tracing system used.
Those submitting data packages to obtain LERAP-Low Drift Star Ratings are encouraged to submit as much relevant information as possible to enable an accurate definition of downwind drift profiles for both candidate and reference spraying systems. Data will be reviewed by comparing downwind drift deposition profiles for the candidate sprayer and the reference system with standardised reference drift profiles (see Figure 1.). Where the form of the downwind drift profile for the candidate sprayer differs from that of the reference system, a LERAP-Low Drift Star Rating will be awarded based on the highest level of drift in the 2.0 to 6.0 m region downwind of the end of the boom.
Nozzles or other spray generation systems (spray generators)
Protocols have been developed and published for sampling the airborne and sedimenting spray from both static and moving nozzles in wind tunnel conditions. Data can therefore be generated using such protocols with details of the measurement method being fully reported with the test results.
Results from such tests must report a minimum of:
1. The measured downwind airborne spray deposits collected at three separate distances between 2.0 and 6.0 m from the edge of the spray pattern from the spray generator(s), using collectors positioned 0.5 m below the spray release height designed to sample sedimenting spray drift; or the measured downwind airborne spray deposits collected at three separate heights between 0 and 0.5 m below the spray release height at a set distance of 2 m or greater from the downwind edge of the spray pattern from the spray generator(s), using collectors designed to sample airborne spray;
2. a description of the wind tunnel arrangement and sampling systems used including:
- details of the spray generator mounting;
- a description of the airflow conditions including the mean wind speed at spray generator height;
- a description of the position and dimensions of the spray sampling system;
details of the tracing techniques used;
the floor conditions onto which the spray generator was spraying;
the sampling periods and methods of controlling spray generator output.
3. Data as in (i) and (ii) above for both the candidate spray generator system and a nozzle representative of the reference;
4. Evidence to validate the experimental procedures used including:
5. The calibration of control and monitoring equipment used to measure/control nozzle operating pressures, flow rates and wind tunnel air speeds;
6. The recovery and stability of the tracing system used.
Data will be reviewed by comparing downwind drift deposition profiles for the candidate and reference nozzles with standardised reference drift profiles. Where the form of the downwind drift profile for a candidate spray generator differs from that of the reference system, a LERAP-Low Drift Star Rating will be awarded based on the highest level of drift in the region 2.0 to 6.0 m downwind of the edge of the spray pattern.
Data packages based on results from existing field trials and wind tunnel experiments ('interpolated data")
It is recognised that for some sprayers and spray generators there may be a large body of drift performance data collected using protocols that differ from those referred to in 3.1 above which could be collated and interpolated to support a case for awarding a LERAP-Low Drift Star Rating. Such collation and interpolation must aim at generating a downwind spray drift deposition profile for the region 2.0 to 6.0 m downwind of a boom or nozzle spray pattern that can be compared with standardised profiles. Any such data package must demonstrate:
1. That the data used was collected in a way such that the likely accuracy and reliability can be validated;
2. That the methods of collation and interpolation are technically robust and reliable;
3. That results can be compared with those for the reference sprayer/nozzle condition.
Source: HSE
List of spray drift reducing nozzles
Spray equipment that has received low drift star rating data packages.
Competent bodies
Laboratories accredited for reviewing low drift star rating data packages
Useful links and documents
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DEFRA - Pesticides - Best Practice
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The LERAP Scheme - Operator Advice
