ARS | Publication request: METHODS OF DRIFT CONTROL

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 17, 1998
Publication Date: N/A

Technical Abstract: Factors effecting the amount of spray drift include: spray droplet size, droplet release height, wind velocity and direction, air temperature and relative humidity, atmospheric stability, and droplet release velocity. These factors are important to several application methods, i.e., aerial, ground boom, and air-blast tree sprayers. Downwind deposits from spray drift can be minimized by optimizing these factors, i.e., spraying a low percentage of driftable droplets (< 150 um), releasing droplets close to the target, spraying in cool humid conditions, with low wind velocities. Of course, if integrated pest management techniques are applied, wherein spray is applied only when required, then less spray will be applied and drift will be automatically reduced. This review discusses examples of drift measurements using boom and air-blast sprayers, and lists management practices for minimizing drift for each application method. For ground boom sprayers, drift management practices include: air-assisted sprayers, electro-static sprayers, using nozzles designed to produce larger droplets and fewer small droplets, and using mechanical shields to reduce the effect of wind. For orchard spraying, one drift reduction technique is to use special spray treatments on the last few downwind rows, including spraying only into the wind or using special nozzles that produce large droplets. Other drift reduction techniques include: use special equipment, such as tunnel sprayers; using hedgerows to filter out spray droplets from the air; and matching the sprayer air jet velocity and volume to the tree being sprayed, and applying the proper spray volume for the tree canopy being sprayed.