Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2011
Publication Date: 6/22/2011
Citation: Zhu, H., Altland, J.E., Derksen, R.C., Krause, C.R. 2011. Optimal spray application rates for ornamental nursery liner production. HortTechnology. 21(3):367-375.
Interpretive Summary: Production of red maple liners (or saplings) is an essential process for providing abundant bareroot stocks for the ornamental nursery industry to beautify our environment. The liners are normally planted densely and grow rapidly during a growing season. Because this production circumstance can aggravate the severity and incidence of insect infestations and diseases, insecticides and fungicides are used routinely to suppress and control pests and diseases. In response to an onset of pest infestations and diseases, spray applicators must make calculated decisions within a very narrow time window on how much pesticide and spray volume is needed for economical control. This research quantified the amount of spray deposition and coverage inside ornamental nursery liner canopies from over-the-row frame vertical boom sprayer, determined its optimal application rates, and established a spray rate model for different size liners. Based on the research findings, growers now have scientific guidelines to increase spray application efficiency, minimize potential environmental contamination due to over application of pesticides, maximize the effectiveness of pest management strategies, and achieve real cost savings for their liner production.
Technical Abstract: Spray deposition and coverage at different application rates for nursery liners of different sizes were investigated to determine the optimal spray application rates. Experiments were conducted on two and three-year old red maple liners. A traditional hydraulic sprayer with vertical booms was used to apply the spray applications. Application rates were 94, 187, 281 and 374 L/ha for the two-year old liners, and 187, 374, 561 and 748 L/ha for the three-year old liners. Nylon screens were used to collect spray deposition of a fluorescent dye suspended in water, and water sensitive papers were used to quantify spray coverage inside canopies. Spray deposition, coverage and droplet density inside both two- and three-year liner canopies increased as the application rate increased. The optimal rates to spray 2.1 m high two-year old red maple liners and 2.7 m high three-year old liners were 187 L/ha and 374 L/ha, respectively. An exponential equation was derived from these results to estimate the spray application rate required for different tree liner heights, and to minimize excessive chemical use in rapidly growing tree liners.