Evaluation of real-time stereo vision-controlled variable rate sprayer performance in grapevine shoot detections and spray application

Authors: Jeon, Hongyoung; Zhu, Heping

Submitted to: Smart Agricultural Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2025
Publication Date: 6/12/2025
Citation: Jeon, H., Zhu, H. 2025. Evaluation of real-time stereo vision-controlled variable rate sprayer performance in grapevine shoot detections and spray application. Smart Agricultural Technology. Article 101101. https://doi.org/10.1016/j.atech.2025.101101.
DOI: https://doi.org/10.1016/j.atech.2025.101101

Interpretive Summary: Safeguarding grapevines from pests and diseases is essential to yield a large quantity of high-quality grapes. Recurring crop protection product (CPP) applications on grapevines during a growing season lead to grape yield as desired, however, a concern is that the recurring CPP applications spray CPP regardless of grapevine presence and its canopy conditions. As a result, a large portion of CPP is deposited on unintended areas other than grapevine canopies during the applications. Therefore, directing CPP sprays to grapevine canopies would reduce overall CPP use and limit its drifts to unintended areas. A prototype vineyard sprayer was developed to apply CPPs only to grapevines. The sprayer used a stereo vision system as a grapevine canopy detection sensor and controlled the opening and closing of spray nozzles with electric solenoid valves. The prototype performance in detecting grapevine canopies was evaluated over a growing season. The spray deposit and coverage of the prototype on grapevine canopies were also evaluated in comparison with a conventional sprayer. The results show that the prototype traveling at 3.2–8.0 km/h detected 95.1%–99.8% of grapevine canopies under cloudy and sunny conditions when the average canopy lengths were longer than 4.1 cm. The prototype sprayer applied a similar volume as a conventional sprayer, although its spray deposition and coverage were significantly better than or comparable to a conventional sprayer. The results of this work can be used to develop an automatic vineyard sprayer that directs CPP spray to grapevine canopies to minimize off-target CPP applications.

Technical Abstract: Use of plant protection products (PPP) for plant protection can be substantially reduced by applying PPP on plants only. A novel variable–rate sprayer with a stereo vision system to apply PPP only to grapevines was developed for vineyard applications. The stereo vision system was evaluated as a grapevine shoot detection sensor under various conditions in average grapevine shoot lengths (4.1–29.1 cm), travel speeds (3.2–8.0 km h-1) and outdoor illuminations (12718 – 67912.0 lx). A real-time variable–rate sprayer prototype with two air assistance levels at the air outlet (low (air speed of 5.9 m s-1) and high (11.3 m s-1)) tested for its spray performance against a conventional sprayer. The results show that the stereo vision system detected 95.1% to 99.8% of grapevine shoots in average under various conditions, and no influences of the shoot size, outdoor illuminations, and travel speeds on the shoot detection were observed under the test conditions. The prototype sprayer had up to approximately 2.8 times more spray deposit averages compared to the conventional sprayer, which was a significant increase (p<0.05). Insignificant increases of spray deposit on grapevine shoots next to the sprayer, and spray drift to an adjacent row were observed from spray applications with low and high air assistance. A similar trend was observed in spray coverage data. These results demonstrate that the novel stereo vision real-time variable rate sprayer is feasible for vineyard applications.