A “double nozzle” configuration combining the spray clouds from medium and fine nozzles is being evaluated at LPCAT. The “nozzle” is designed to exploit the air entrainment characteristics of a medium or coarse spray in order to contain and target the “drift prone” but biologically efficient AI containing smaller droplets produced by a fine nozzle.
The dynamic deposit pattern from different nozzle combinations and spacings was evaluated. Fine sprays had more variable patterns than coarser sprays. Optimizing nozzle spacings improved the deposition uniformity of the fine sprays, although uniformity was still sub-optimal.
Efficacy studies using glyphosate on soybeans and dicofol against mites on lima beans indicated that the fine spray was generally better than the coarser spray, and the combined spray tended to have greater efficacy than the coarser spray. Droplet coalescence of the deposit somewhat reduced the effectiveness of the combined spray compared to the fine spray alone, but a significant reduction in pesticide use compared to conventional sprays could still be demonstrated using the “double nozzle”.
Future studies, also encompassing biopesticides, will focus on optimizing spray deposit effectiveness through a combination of coarse, dilute sprays and fine, concentrated sprays. Attention will also be focused on patternation and distribution of the fine spray within different canopies.