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Equipment to Reduce Spray Drift

• Do you want to keep more of your product on target?
  
• Do you want to extend your spray window (a little)?
  
• Do you want to improve the overall effectiveness of your applications?
  
• Do you want to reduce the risk of off-target deposition?

Of course you do!

That's why you want to make adjustments to your spray equipment to reduce pesticide drift.

Spray drift is everyone's responsibility. When applying pesticides near sensitive crops, areas of human habitat, or environmentally-sensitive areas such as open water, all reasonable precautions must be taken to prevent spray drift. Extremely low, and often invisible, amounts of spray drift can be very damaging; even long after the application.

While there are many types of agricultural sprayers used for the ground application of pesticides, the two most often associated with spray drift are the airblast sprayers (including cannon sprayers) and the boom sprayers (typically horizontal).

Generally, the goal is to produce a coarser spray quality and bring the nozzle as close to the target as possible, without compromising coverage or spray quality. There are a variety of ways to modify your sprayer to accomplish this:

For airblast sprayers the potential for drift can be reduced by:

• adjusting fan settings to produce the minimal effective air speed throughout the season. High fan speeds early in the season are almost never appropriate;
  
• increasing droplet size by using lower pressures, air-induction nozzles or disc-core (or disc-whirl) nozzles that produce a coarser spray quality;
  
• using deflectors to channel air into, not over or under, the target;
  
• using towers to reduce distance-to-target and direct air into the target. Be careful not to get any closer than 50 cm;
  
• using foliage sensors that turn boom sections on and off to match the size and shape of the canopy; and
  
• switching to a tangential, recycling, multi-duct, or multi-fan sprayer, all of which reduce off-target deposition. Many of these sprayers are rare in Ontario, but they are available. Ask you local retailer for more information. Many pay for themselves in saved pesticide.

For horizontal boom sprayers the potential for drift can be reduced by:

• maintaining a minimal effective boom height;
  
• using low-drift nozzles, such as air-induction, drift-guard, turbo tee jet, etc.;
  
• using drop-arms to bring nozzles closer to the target;
  
• using the appropriate spray angle. Wider spray angle nozzles (e.g. 110°) create smaller droplets than nozzles with narrower spray angles (e.g. 80°). Although smaller droplets generally increase the chance of drift and reduce penetration in dense canopies, the wider angle nozzles allow the boom to lie closer to the target;
  
• using air-assist to direct spray into the canopy; and
  
• using shrouds to create physical barriers to drift;

Be aware that the equipment described here can reduce, but does not eliminate pesticide drift. Spraying in bad weather and not accounting for the nature of the target increases the potential for drift (see Figure 1).

Figure 1. Even with the best equipment, weather plays a big role in increasing or decreasing the potential for pesticide drift. Check out OMAFRA factsheet 09-037W How Weather Conditions Affect Spray Application.

If you'd like to know more about spray drift, methods for preventing it and what to do if you suspect drift damage, keep an eye out for a new OMAFRA Factsheet on Pesticide Drift - it should be available before next year's spraying season. In the meanwhile, be sure to check out the videos hosted by the Ontario Pesticide Education Program.