ARS | Publication request: Performance evaluation of a newly developed variable rate sprayer for nursery liner applications

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 2011
Publication Date: January 6, 2012
Citation: Jeon, H., Zhu, H., Derksen, R.C., Ozkan, E., Krause, C.R. 2012. Performance evaluation of a newly developed variable rate sprayer for nursery liner applications. Transactions of the ASABE. 54(6):1997-2007.

Interpretive Summary: Properly applying chemicals to nursery liner crops is essential to protect them from biological harm and maintain their quality. However, few application technologies have been specifically designed for these crops and nursery growers have to use either orchard or modified ground sprayers for their chemical applications. An experimental variable-rate sprayer was designed and tested for liner applications in a laboratory plot. Its spray deposit, coverage, and droplet density inside canopies of various nursery liner varieties was compared with constant-rate applications. The variable-rate application had lower variation in spray deposits inside tree canopies than constant-rate applications. Moreover, spray volume savings of the variable-rate sprayer were up to 71% compared to the conventional application of the constant rate that was normally recommended for liner spray applications. Therefore, the newly developed variable-rate sprayer would bring great reductions in pesticide use and safeguard the environment for the nursery liner production

Technical Abstract: An experimental variable-rate sprayer designed for liner applications was tested by comparing its spray deposit, coverage, and droplet density inside canopies of six nursery liner varieties with constant-rate applications. Spray samplers, including water sensitive papers (WSP) and nylon screens, were mounted inside tree canopies to collect spray deposit and coverage from variable- and constant-rate (555 and 1,110 L/ha) applications. Models for estimating spray volume savings of the variable-rate sprayer compared to a constant-rate and Tree-Row-Volume (TRV) based rate applications were developed for various liner canopy sizes and tree spacing. The accuracy of the model was validated with the field test data. For the liner trees tested, the variable-rate sprayer delivered 151 to 359 L/ha application rates while the conventional constant-rate application required 1,110 L/ha. Due to substantially lower spray output, the variable-rate application had relatively lower but sufficient spray deposit, coverage, and droplet density than the constant-rate applications. Also, the variable-rate application had significantly less variations in spray deposit within the canopies of different size trees. Test results showed that the variable-rate sprayer reduced spray volume up to 86.4 % and 70.8 % compared to the 1,110 L/ha and TRV based rate applications, respectively, while the model estimated savings were up to 94.6 % for the 1,110 L/ha application, and 57.7 % for TRV based rate applications.