Date of Graduation

8-2017

Document Type

Thesis

Degree Name

Master of Science in Agricultural & Extension Education (MS)

Degree Level

Graduate

Department

Agricultural Education, Communications and Technology

Advisor/Mentor

Johnson, Donald M.

Committee Member

Edgar, Don W.

Second Committee Member

Graham, Donna L.

Third Committee Member

Davis, Jason

Keywords

Burndown; Efficacy; Sprayer

Abstract

An Apache AS1220 self-propelled boom sprayer with a 27.4 m (90 ft) boom was equipped with different sizes (02, 04 and 06) and types (TeeJet AI, XR, AIXR and TTI) of nozzles to achieve medium, very coarse and ultra coarse droplet sizes traveling 11 km/h (7 mph), 19 km/h (12 mph), and 29 km/h (18 mph). These combinations of speed and droplet size were evaluated for percent coverage of the spray and percent control of targeted weeds 3, 7, and 15 days after treatment (DAT). Four replications were conducted for each speed and droplet size combination except for at 19 km/h (12 mph) where only three replications were used (35 plots). Significant (p < 0.05) differences were found in percent coverage by travel speed (F(2) = 16.15, p = <.0001) and by droplet size (F(2) = 5.09, p = 0.01) but not by the interaction of travel speed and droplet size. A travel speed of 18 mph (M = 9.35, SD = 0.94) and a very coarse droplet size (M = 8.71, SD = 1.30) were found to have the highest mean percent coverage among the groups. Significant (p < 0.05) differences were found in percent control by travel speed and droplet size but not the interaction of travel speed and droplet size at 3 and 7 DAT. No significant (p < 0.05) differences were found 15 DAT. A travel speed of 11 km/h (7 mph) (M = 77.58, SD = 10.58) and a medium droplet size (M = 76.63, SD = 11.46) were found to have the highest mean percent control at 3 DAT. A travel speed of 29 km/h (18 mph) (M = 88.33, SD = 6.15) and a medium droplet size (M = 89.09, SD = 4.90) were found to have the highest mean percent control at 7 DAT. Results suggest that an applicator planning to operate at increased field speeds, should consider selecting a nozzle that will produce a larger droplet when combined with their chosen travel speed. Moreover, no significant (p < 0.05) differences were found 15 DAT, suggesting that applicators should select a nozzle based on its ability to control drift at a given travel speed.

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