Over the last couple of years, we identified and developed two high speed, precision spot sprayers to apply herbicides to weeds with minimal off-target spray while traveling at speeds that are viable for commercial vegetable farming operations (2 mph). The first is a spray assembly designed for controlling in-row weeds that are close to crop plants (1-cm spot spray resolution). The second is a high precision (sub-centimeter spot spray resolution) sprayer designed for spot spraying cotyledon stage weeds in spinach and leaf lettuce crops. We tested the device in the laboratory and found that weed control efficacy was greater than 95% (3 species), percentage of off-target spray was less than 3% and no crop injury was observed. The work was presented at the 2021 California Weed Science Society Annual Meeting. Click here or on the image below ) to view the presentation and see video of the devices in action. 

We are now working towards developing a high precision, automated/robotic weeding machine for vegetable crops. This fall, Evan McGinnis, Biosystems Engineering Ph.D. candidate, initiated work to develop AI-based imaging software for detecting and targeting weeds. Once developed, the software will be integrated with the precision spot sprayer and tested in the field. Stay tuned for updates!

Acknowledgements

This work is supported by the Arizona Specialty Crop Block Grant Program and the USDA NIFA Specialty Crops Research Initiative USDA-NIFA-SCRI-004530. We greatly appreciate their support. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

Fig. 1. Images from “Centimeter Scale Resolution Sprayer for Precision In-Row Weed Control” presentation given at the 2021 California Weed Science Society Annual Meeting. Click here or on image to view the presentation.