Advancing Options for Management and Mitigation of
Spray Drift
Risk Mitigation Measures in Europe to Prevent Plant Protection Product losses to the Environment
Train Operators to Promote best Practices & Sustainability
TOPPS is a multi-stakeholder project started 2005 covering 23 European Countries to reduce PPP losses to water from point sources and 12 EU countries to reduce PPP water contamination from spraydrift and runoff. - it stands for Train
Operators to Promote best Practices & Sustainability. First TOPPS project up to end 2008 was jointly funded by the European Commission's Life program and by ECPA, the European Crop Protection Association (Projects since 2008 are funded by ECPA only). TOPPS is aims at developing Best Management Practices, risk diagnosis tools and training materials as well as disseminating them through advice, training and demonstrations at a larger co-ordinated scale in Europe with the intention of reducing losses of plant protection products to water.Relevant studies and publications on strategies to manage point-source releases of plant protection products into surface waters were collected and analysed to better understand the challenges and options. This review exercise led to the development of a series of Best Management Practice (BMP) recommendations to reduce point sources, spray drift, run-off and erosion. Resources developed by TOPPS include:
BMP’s are disseminated through trainings (theory and practise), TOPPS - academy, workshops, presentations and publications. Dissemination activities are mainly targeted to advisers, farmers, stakeholders and students. These dissemination activities are performed in the countries by local partners ranging from science (Universities) to farm advice to create awareness and support implementation of BMPs. To facilitate training and demonstration the TOPPS websites also includes helpful resources such as:
As a component of these efforts, the dissemination strategy has included a training programme based upon demonstration farms. and pilot catchments areas to show and demonstrate the BMP’s.
To support broader practical implementation in the field the TOPPS project also developed a tool to support more effective drift management for field, orchard and vine applications (TOPPS Drift Evaluation Tool).
Recommendations
Mitigation measures to reduce spray drift can be classified in direct and indirect measures.
1. Direct measures, aimed to reduce spray drift at the source (formation and direction of the spray droplets). These measures are mainly addressed through application technologies, sprayer accessories designed to optimize spray drift generation and correct sprayer adjustment.
2. Indirect measures, aimed to reduce spray drift by measures to “capture spray drift” like buffer zones, no spray zones or barriers (e.g. windbreaks, hail nets, etc.).
Environmental factors
Before starting an application, environmental factors relevant for a spray drift risk should be considered. Key point: the distance from a crop to be sprayed to any sensitive area and the presence/absence of indirect mitigation measures like buffer strips (e.g. hedges, windbreaks, other structures able to capture spray drift).
Other major factors especially in orchards and vineyards are:
1) The canopy structure of the crop
2) The evenness of canopy wall along the row (absence of space between adjacent plants)
3) Growth stage/status of the crop. Key consideration is the leaf density and leaf area able to capture the spray and keep it in the target area.
Spraying equipment
Beside the correct use of PPP, the spray equipment is the key element in spray drift reduction.
It is important to take the following three aspects into consideration:
1. Droplet spectrum
2. Application technique and easy adjustment of sprayers (including air support)
3. Modification of sprayer parameters according to environmental factors and crop characteristics.
Sprayers should be classified according to their spray drift-reduction potential (known as Spray Drift-Reducing Technology (SDRT). The sprayers are divided into spray drift mitigation classes, e.g. 25%, 50%, 75%, 90%, 95% or 99% (see ISO 22369-1)
SDRTs are classified separately for different crop types, e.g. arable crop, fruit crop (dormant and full-leaf growth stage), hops, vineyard and nursery. In some countries, the use of SDRT results in modified distance regulations for the applied PPP.
Sprayer operation
Sprayers should be operated so that only the target area is treated. This requires special attention at field boundaries and, when necessary, the use of drift-reducing measures.
The interplay between these various factors is well illustrated as application strategy management support in the TOPPS Drift Evaluation Tool.
Weather conditions
Weather conditions are the main influencing factors for spray drift. Wind speed, wind direction, air humidity and temperature are the key factors which need consideration.
Wind speed influences the amount of fine droplets, transported away from the target area. The wind direction determines the direction of the spray “cloud” and if it drifts towards a sensitive area.
When air humidity is low, water from the small spray droplets can evaporate, increasing the amount of fine droplets. When air temperature is too high, thermal effects tend to lift up small droplets and delay the sedimentation of the spray (thermal drift), prolonging the possibility of the transfer through wind.
Sprayer adjustment
Sprayer adjustment is largely related to the behaviour of the operator and the adjustment options of the sprayer. Operators are obliged to regularly calibrate their sprayers (EU Directive 2009/128 EC). Calibration means: be sure that the sprayer can be operated according to the requirements of good agricultural practice.
a) Sprayer parameters should be adjusted and checked to apply the correct amount of PPP to the crop.
b) Correct adjustment of the sprayer means the potential losses of PPP to the environment are minimized (e.g. spray drift).
These checks should be performed several times during the season, because the crop composition changes (e.g. leaf areas of the crops in plantation crops).
c) Big challenge is the adjustment of the air profile in Bush and Tree Crop sprayers where technical limitations often do not allow good ajustments.