ID 404

ROLE OF ADJUVANTS ON SPRAY DROPLET SPECTRA OF PLANT GROWTH REGULATORS

 

Abstract:

WinField Solutions Plant growth regulators (PGRs) are routinely used to manipulate growth and development of horticulture and agricultural crops. They elicit plant responses at low concentrations and have a narrow optimum dose response range. PGRs may be applied to the soil or as a foliar spray and are often applied in conjunction with other crop protection products or mineral nutrition. The effectiveness of foliar applications is dependent upon successful delivery to the target where the spray solution may be absorbed by plant tissue. Non-uniform distribution of the prescribed dose over the intended target could affect PGR efficacy and lead to inconsistent performance. This study evaluated the droplet spectra variety of PGRs alone and in combination with glyphosate as affected by adjuvants using a Sympatec HELOS-KR laser diffraction particle size sensor in a fully enclosed low speed wind tunnel. Active formulations were delivered using field-appropriate rates, nozzles, and pressures in a fully enclosed low speed wind tunnel. Air flow of 8 ± 0.5 mph was concurrent with the spray direction, preventing repeated sampling of very fine particles. The effect of adjuvants on various spray parameters was measured. These parameters included: (1) the cumulative percent of spray volume comprising droplets smaller than 105 μm, or “driftable fines,” and the percent change in this quantity relative to a standard; (2) the volume median diameter (DV0.5), or diameter at which 50% of the volume includes smaller droplets, as well as the DV0.1 and DV0.9 (10% and 90%, respectively); and (3) the relative span, calculated using (DV0.9-DV0.1/DV0.5).