Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Proceedings
Publication Acceptance Date: 12/30/2002
Publication Date: 1/15/2003
Citation: GARR, J.A., HANKS, J.E., WILLS, G.D., JONES, E.J. EFFECTS OF ADJUVANTS AND SPRAY DROPLET SIZE ON VELVETLEAF CONTROL. PROCEEDINGS OF SOUTHERN WEED SCIENCE SOCIETY. Interpretive Summary:
Technical Abstract: Preliminary studies were conducted at Stoneville, MS to determine the effect of drift retardant polymers on spray droplet size, spray patterns and efficacy when used with Roundup Ultra®. Spraying Systems Turbo TeeJet®, 110015vp nozzles were used and calibrated to apply 94 L/ha at 7.4 km/hr. Array®, Spray Start® and Control® were commercially available adjuvants and GP D1 an experimental product evaluated. Each product was applied at two rates with Roundup Ultra® at 0.6 kg ai/ha. Ammonium sulfate was added to Control since it was contained in all the other products. Roundup Ultra® was applied with and without ammonium sulfate added. Visual ratings (0-100) were recorded 3 WAT. A Malvern laser particle analyzer was used to determine the volume median diameter and percent spray volume in droplets less than 144 microns. All treatments provided excellent control of velvetleaf with only the Roundup Ultra with no additional adjuvant being significantly lower than all other treatments. There were no significant differences among treatments with any type additional adjuvant, including the addition of only AMS to Roundup Ultra. Since all treatments included AMS except for the one treatment with Roundup Ultra alone, indications are that the addition of AMS had more effect on velvetleaf control than addition of the drift retardant adjuvants. Spray droplet analyses indicated all drift retardant adjuvants increased the volume median diameter and reduced the percentage of spray volume in droplets less than 144 microns.