ADJUVANTS can affect the droplet sizes produced by air inclusion and twin-fluid nozzles in a significantly different way to their effect on conventional flat fan nozzles.
"Farmers need to be aware that adjuvants used with air included nozzles may affect spray quality very differently," Clare Butler-Ellis of Silsoe Research told the AAB Pesticide Application Conference at the University of Surrey, Guildford, last week.
Three different air inclusion nozzles, a twin fluid nozzle and a conventional flat fan jet were tested in the study, which compared sprays applied with and without adjuvants.
Overall droplet size increased with conventional tips when using five of the eight adjuvants tested. However, most of the air including jets reduced the droplet size, especially with a soya lecithin adjuvant.
Synthetic latex, nonyl phenol and tallow amine adjuvants reduced droplet size with conventional fan jets, but increased droplet size with three of the four air including nozzles – by over 20% when using tallow amine with the twin fluid nozzle.
Furthermore, one of the air inclusion jets consistently performed very differently from the other two.
Differences in droplet size may stem from the effect adjuvants have on the amount of air included, which may also affect their speed of travel, said Mrs Butler-Ellis. *