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Title: Spray deposition inside multiple-row nursery trees with a laser-guided sprayer

item Zhu, Heping
item LIU, HUI - Jiangsu University
item SHEN, YUE - Jiangsu University
item ZONDAG, RANDY - The Ohio State University

Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2017
Publication Date: 8/7/2017
Publication URL:
Citation: Zhu, H., Liu, H., Shen, Y., Zondag, R. 2017. Spray deposition inside multiple-row nursery trees with a laser-guided sprayer. Journal of Environmental Horticulture. 35(1):13-23.

Interpretive Summary: There are much more variabilities in tree architectures in ornamental nurseries than any other fruit tree crops. Multiple-row planting has been suggested to maximize the number of nursery plants that can be grown in a given area. However, sprayers used in nurseries are adopted from other crops. Hence, the spray efficiency is very low. Specially designed sprayers are needed to improve pesticide application efficiency and reduce pesticide waste to the environment. In this research, a laser-guided, air-assisted sprayer was designed and evaluated to discharge variable-rate sprays for multiple-row nursery crop production. The sprayer was coupled with pulse width modulated solenoid valves to control nozzle flow rates based on tree structures detected with a laser scanning sensor. Field tests demonstrated that the newly developed sprayer could significantly reduce spray volume for multiple-row nursery crop production while providing adequate spray deposition and coverage inside canopies; thereby offering an environmentally responsible spray technology for the nursery industry to protect crops against damage from insects and diseases.

Technical Abstract: Multiple-row container-grown trees require specially designed sprayers to achieve efficient spray delivery quality. A five-port air-assisted sprayer with both automatic and manual control modes was developed to discharge adequate spray deposition inside multiple-row tree plants. The sprayer resulted from integration of a high-speed laser scanning sensor with a sophisticated nozzle flow control system, an embedded computer with a touch screen, a Doppler speed sensor, a specially-designed algorithm and an air-assisted sprayer base. It was able to detect target tree presence and measure target tree size, shape and leaf density. The sprayer then controlled spray outputs of each nozzle to match tree structures. The sprayer was tested for its sprayer deposition quality inside canopies in a four-row sterling silver linden field (Plot #1) and another six-row northern red oak field (Plot #2). Tests were conducted with the sprayer in variable-rate application (VRA) and constant-rate application (CRA) modes. The average spray deposit on foliage of trees was 1.37±0.47 µL cm-2 from VRA and 1.29±0.42 µL cm-2 from CRA in Plot #1, and was 2.15±0.57 µL cm-2 from VRA and 2.72±0.94 µL cm-2 from CRA, respectively. In comparison, spray coverage on foliage of trees was 19.8±3.0% from VRA and 20.9±4.3% from CRA in Plot #1, and was 27.9±3.7% from VRA and 30.5±5.4% from CRA, respectively. The newly developed air-assisted sprayer in both VRA and CRA modes would be able to discharge adequate spray deposition inside multiple-row tree plants while conserving pesticide.