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Title: The impact of spray modifiers on pesticide dose transfer.
Author: Downer, Roger Anthony.
ISNI:       0000 0001 3431 4209
Awarding Body: University of Portsmouth
Current Institution: University of Portsmouth
Date of Award: 1998
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The impact of adjuvants on atomization and patternation of spray mixtures was evaluated. The data showed that certain adjuvants, in particular drift control agents, could potentially detrimentally affect the distribution of herbicide dose across the sprayed swath. The present research sets out to evaluate the impact of this distribution and to seek ways of improving the way researchers and users characterize and possibly mitigate these effects with a view to minimizing the potential detriments and maximizing the efficiency of herbicide active ingredient (AI) utilization. Different formulations of glyphosate with and without a novel polymeric drift control agent (AgRho DR 2000) applied to contrasting broad-leaved and grass weeds were used to evaluate several effects of polymer use. Variables included nozzle type (XR TeeJet extended range flat spray tips, TT Turbo TeeJet wide angle flat spray tips, and TurboDrop air induction nozzles) sampling position (principally under the nozzle centers and under the overlap between two adjacent nozzles), boom height (30, 45, and 60 cm above the target), spray delivery (the volume of spray arriving at the target), spray retention ( the volume of spray actually retained by the target foliage), and herbicide efficacy ( the response of the target weeds to the herbicide dose applied). The data showed that when the polymer was included in the spray mixture, the nozzle used, boom height, presence of the adjuvant, sampling position and certain interactions between these variables were all significant. Spray retention was affected by plant type and retention of coarse sprays was improved by the inclusion of DR 2000. Very coarse sprays reduced glyphosate efficacy on both grasses and broad-leaved weeds although that effect was reduced by use of DR. Addition of drift control agents always ii resulted in increased variability in spray distribution with concomitant increases in both retention and efficacy variability. Variability was shown to decrease with decreasing boom height. There was little correlation between spray delivery and herbicide efficacy. Deposit structure was shown to be a highly important factor in understanding herbicide dose transfer. A novel methodology utilizing digital imaging technology and diversity statistics was developed and evaluated to improve the way we measure and characterize deposit structures. Separation of qualitatively different treatments with similar volumetric distributions was possible. This methodology will be of use to both biologists and fOnTIulation chemists for prediction or explanation of biological results relating to deposit structure. Use of Scanning electron microscopy, and epi-fluorescence microscopy was used to characterize deposit morphology. Differences in deposit morphology were observed and documented leading to a possible explanation for the enhanced glyphosate activity in the presence of DR 2000 iii
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Atomization; Patternation; Adjuvants; Herbicide