Date of Award
Doctor of Philosophy
Micheal D. K. Owen
Nick E. Christians
Many lawn care operators use the lawn spray gun spraying system to alleviate potential non-target injury from postemergence broadleaf herbicide spray drift. This system was designed to apply dilute fertilizer and pesticide solutions at high spray volumes and low nozzle pressure. The lawn spray gun application at a mean volume rate of 1122 L ha[superscript]-1 in comparison to flat fan nozzles at 187 L ha[superscript]-1 or Raindrop nozzles at 374 L ha[superscript]-1 significantly reduced the injury potential to non-target plants 90 cm or more from the spray swath edge. The direct deposition of spray at the 30 cm downwind location suggests that a small unsprayed buffer area next to non-target plants should be left in order to avoid direct spray contact to non-target plants for all nozzle types tested. The percentage of spray recovered indicates that large differences do occur within the spray swath. The corresponding coefficient of variation (CV) values for the nozzle types were above the recommended CV value of 15%; however, other research has shown that applications with a CV range of 14% to 28% provided satisfactory uniformity for droplet deposition. The low percent spray recovery with RA-6 nozzles and the spray gun on turfgrass suggests that droplets produced by flat fan nozzles may have greater collection efficiencies than those by RA-6 nozzles or the spray gun. Simulated spray drift on annual flowers indicates that petunia (Petunia x hybrida) is extremely sensitive to the triethylamine salt of triclopyr ((3,5,6-trichloro-2-pyridinyl)oxy) acetic acid or the dimethylamine salt of 2,4-D (2,4-dichlorophenoxy)acetic acid, while impatiens (Impatiens wallerana) is one of the least sensitive species tested. Triclopyr tended to be more injurious than 2,4-D even though species sensitivity to each herbicide varied.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Harlene Mae Hatterman-Valenti
Hatterman-Valenti, Harlene Mae, "Spray deposition and drift during postemergence herbicide applications to turfgrass and annual flowers " (1993). Retrospective Theses and Dissertations. 10237.