Make use of drift reducing spray techniques

Wageningen UR investigated two spraying techniques that can lower drift: the wingssprayer (name of sprayer by producer http://www.sleepdoek.nl/) and air-assisted spraying.
The wingssprayer has hard plastic flaps attached to the spraying boom. These act as windshields and create a downward airflow. The fine droplets are deposited into the crop. By spraying with air-assistance the fluid flow is supported by a downward airflow. Most systems use an airbag with air gaps or holes at the bottom.
Advantages of both systems over a conventional sprayer are:
• better penetration into the crop
• less pesticide needed for a good result (ca. 20%)
• reduction of cost for pesticides (approximately 20%)
• more sprayable days
• less drift (wingssprayer: 72-99%; air-assistance: 95%)
• less environmental side-effects
The cost of purchase and assemblage of the wingssprayer (approximately 33 meter) on a conventional sprayer are about € 10,000(2006). The additional costs for air-assistance on a sprayer of 24 meter are around € 10,000 - € 27,000 (2006).

The efficacy of many applications is hardly affected by droplet size. Nozzle / pressure combinations up to 50% spray drift reduction result in a constant efficacy. The use of nozzles with a droplet spectrum > (with more than) 50% drift reduction decreases the efficacy of low dose systems with herbicides and fungicides used in small open crops (onion and leek). To reduce spray drift as much as possible one should find a combination of the lowest drift nozzle possible (with respect to efficiency) and air-assistance or wingssprayer. An additional benefit of these techniques is that even under difficult weather conditions spraying is possible. The most efficient use of pesticides was examined. No differences were found with the tested doses. The dose steps in the study were 25%. It cannot be excluded that the use of air-assistance or wingssprayer is more efficient, but this difference is less than 25% (this can not be significantly demonstrated in field trials).
Air-assistance is too costly for most arable farms. The spray boom width can be a limiting factor. A wingssprayer can be a good alternative. The wingssprayer system can be built on every conventional sprayer.