Reducing Spray Drift in UK Crop Protection
Keeping spray on target is an important part of effective crop protection.
Off-target movement can reduce the amount of product reaching the crop or weed being treated and increase the risk to neighbouring crops, water, habitats and other sensitive areas.
Spray drift cannot be managed by one measure alone. Weather conditions, nozzle choice, spray quality, boom height, forward speed, application pressure and the characteristics of the product all influence the risk.
The aim is to combine good spraying practice with appropriate drift-reduction technology so that applications are made accurately and within label and regulatory requirements.
What is spray drift?
Spray drift is the movement of spray droplets away from the intended target during application.
The level of drift depends on a combination of factors, including wind speed and direction, droplet size, boom height, nozzle type, pressure, forward speed and local atmospheric conditions.
Smaller droplets are generally more susceptible to off-target movement because they remain airborne for longer.
Hot, dry conditions can also increase drift risk because droplets can lose water through evaporation and become smaller before reaching the target.
Why spray drift is important
Off-target spray movement can affect neighbouring crops, watercourses, field margins, habitats and other sensitive areas.
It can also reduce application efficiency because less of the intended spray reaches the target.
Plant protection products must be applied in accordance with the product label and relevant legal requirements, including any specified buffer zones or drift-reduction measures.
What influences spray drift?
Drift risk is determined by the interaction between weather, machinery, spray quality and operator decisions.
Wind speed and direction
Wind is one of the most important factors influencing drift.
Before spraying, conditions should be assessed in the field rather than relying on forecast information alone.
Applications should not be made where wind speed or direction could carry spray away from the intended target or towards sensitive areas.
Temperature and humidity
Hot, dry weather can increase evaporation from spray droplets.
As droplets lose water they become smaller and more susceptible to drift.
Cooler, more humid conditions generally reduce evaporation and can provide a wider margin for accurate application.
Boom height
Boom height has a direct influence on how long droplets remain airborne.
Operating the boom at the appropriate height for the nozzle and spray angle helps reduce unnecessary drift and maintain an even spray pattern.
Excessive boom height increases the distance droplets must travel and therefore increases the opportunity for off-target movement.
Nozzle choice and spray quality
Nozzle design affects droplet size, spray pattern and flow rate.
Low-drift and air-induction nozzles can reduce the proportion of fine droplets and are widely used where drift reduction is required.
However, spray quality must still suit the target and crop protection product. A coarser spray may reduce drift but could compromise coverage where fine or medium droplets are needed.
Nozzle choice should therefore be based on the product label, target, required spray quality and field conditions.
Pressure and forward speed
Higher pressure can increase the proportion of fine droplets from some nozzle types, increasing drift risk.
Forward speed can also influence boom stability, turbulence and application quality.
The correct combination of speed, pressure and nozzle should be selected to achieve the required application rate and spray quality while maintaining a stable boom.
What is drift reduction technology?
Drift reduction technology, often shortened to DRT, refers to equipment or application approaches designed to reduce off-target spray movement.
This can include low-drift nozzles, air-induction nozzles, boom-height control, shrouded or shielded spraying systems and other approved application technologies.
Where drift-reduction measures are specified on a plant protection product label, they form part of the authorised conditions of use and must be followed.
Low-drift and air-induction nozzles
Nozzle choice is one of the most practical ways to influence spray drift.
Air-induction and other low-drift nozzles are designed to produce fewer fine droplets than conventional flat-fan nozzles.
This can reduce off-target movement while maintaining the spray pattern needed for many applications.
The level of drift reduction achieved depends on nozzle design, operating pressure, boom height and application conditions.
Nozzle choice should always be matched to the crop protection product and target rather than selected on drift performance alone.
Boom-height control
Maintaining a consistent boom height helps improve both coverage and drift management.
Modern boom-height control systems use sensors to respond to changes in crop height or field surface, helping keep the boom within the intended operating range.
This can be particularly useful at higher working widths, where small changes in terrain can otherwise lead to greater boom movement.
Shrouded and shielded spraying
Shrouds and shields can physically reduce the movement of spray away from the target.
These systems are used in some specialist and inter-row applications where greater separation between the spray and surrounding vegetation is required.
Their suitability depends on the crop, application system and product approval.
Can adjuvants reduce spray drift?
Some adjuvants are formulated to modify spray characteristics and reduce the proportion of fine droplets that are most susceptible to drift.
The effect is product-specific.
Adjuvants should only be used where they are compatible with the crop protection product and appropriate for the application.
They do not make unsuitable spraying conditions acceptable and should not be used as a substitute for correct nozzle choice, boom height or weather assessment.
Always follow product labels and current technical recommendations.
Buffer zones and drift-reduction requirements
Some plant protection products have mandatory buffer zones or drift-reduction requirements designed to protect surface water and other non-target areas.
These requirements are stated on the product label and must be followed.
Where a product requires specific drift reduction technology, the application must be made using equipment and settings that meet those conditions.
Practical ways to reduce spray drift
- Assess wind speed and direction at the field before spraying.
- Avoid spraying where conditions could carry droplets towards sensitive areas.
- Use an appropriate nozzle and spray quality for the product and target.
- Keep the boom at the correct operating height.
- Use suitable pressure and forward speed to maintain stable application.
- Check nozzle condition, output and spray pattern regularly.
- Use approved drift-reduction technology where required or appropriate.
- Observe all product label requirements, including buffer zones and application restrictions.
Combining drift reduction with effective application
Reducing drift should not come at the expense of crop protection performance.
The objective is to achieve the required coverage and deposition while keeping spray within the intended treatment area.
This means balancing nozzle choice, droplet size, water volume, pressure and application conditions rather than simply producing the largest possible droplets.
The best approach will vary between products and targets, so application decisions should be based on the individual spray operation.
How agronomy advice supports spray application
Application quality can have a significant influence on crop protection performance.
Your Agrii agronomist can help assess the target, product, crop and conditions and advise on where drift-reduction measures may be appropriate.
This may include nozzle choice, adjuvant use, spray timing and interpretation of product label requirements.
The aim is to keep spray on target, protect surrounding areas and make the best use of the crop protection product being applied.