Impacts of surfactant-based adjuvants on spray droplet size, drift distance, and deposition efficiency

The application of anti-drift nozzles, such as air-induction nozzles, is the most common recommendation for reducing spray drift; To reduce the risk of coarse droplets bouncing and rolling produced by anti-drift nozzles, various types of adjuvants were screened by comparing their atomization performance, surface tension and contact angle, in order to identify favourable adjuvants that are compatible with anti-drift nozzles. It was found from the study results that the addition of 50% neem crude oil emulsifiable concentrate (neem oil), isomeric alcohol ethoxylates and BYK-405 all significantly decreased distribution span (S) and the percentage of droplet size less than 150 μm (ΦVol_<150μm) values, but significantly promoted the median volume (D₅₀) value. And the surface tension measurement results showed that all tested adjuvants significantly reduced the surface tension, while neem oil, FC4430 and silwetl-77 were observed with a most significant effects; Furthermore, all tested adjuvants except BYK-051N could also significantly decrease the contact angle, and the difference between neem oil, FC4430 and silwetl-77 was significant. Wind tunnel test results clearly demonstrated that the application of IDKA (a combination of air-induction nozzle IDK120-01 and neem oil) substantially decreased the drift deposition amount; In addition, the field experiments revealed that IDKA possessed a significantly improved deposition amount per unit area on canopy or bottom, leading to a more effective deposition. These results suggest that the use of IDK120-01 nozzle and neem oil can effectively reduce spray drift, lessen surface tension and enhance spreading.