Over the last couple of years, there has been tremendous investment and research and development in autonomous weeding machines. At least 40 such robots have been promoted all over the world. Two of these available in the Yuma area are Naio Technologies’ Dino¹ and FarmWise’s Titan. If you are not familiar with these technologies, the Naio Dino is a four wheeled, self-driving platform (Fig. 1). The robot is equipped with an imaging system that detects crop rows and an actuator that automatically adjusts the position of cultivating tools relative to the crop row allowing for close cultivation. The FarmWise Titan is an autonomous power unit coupled with an automated weeding machine (Fig. 2). It utilizes an imaging system to detect crop plants. Pairs of knife blades are automatically controlled to open and close around the crop plant to control in-row weeds.
Mosqueda et al. (2021) evaluated the two autonomous weeders in trials with lettuce last summer in Salinas, CA. The results were published in a UC Davis ANR blog article and the highlights are summarized here. In the study, the Naio Dino was equipped with finger weeders, a ground driven rubber fingered wheel designed for in-row weeding. Performance was compared to that of a standard cultivator which left an uncultivated band of 4-5 inches around the crop row. Assessments included stand and weed density counts before and after cultivation, hand weeding time and crop head weight. Weed counts were made in a 6 inches wide band centered on the seedline. The robot is equipped with finger weeders, a ground driven rubber fingered wheel designed to remove in-row weeds.
Trial results showed the finger weeder equipped Naio Dino controlled more than 1/3^rd of the in-row weeds and reduced hand weeding time by about 2 hours per acre. This result is consistent with our findings in trials conducted in cotton crops where finger weeders controlled about 40% of the in-row weeds. Crop stand and head weight were not significantly reduced as compared to standard cultivation.
Similar results were found with the FarmWise Titan. The automatically controlled paired knife-blade weeding tool generally provided 40-50% in-row weed control and crop stand or yield was not significantly affected. As you might expect, reductions in hand weeding time were highly dependent on weed pressure. When weed density was low (<0.2 weeds/ft²) labor savings were negligible (< 0.1 hours/acre). At moderate weed (1.7 weeds/ft²) and high densities (>7 weeds/ft²), labor savings were more substantial at 1.7 hours/acre and > 7 hours/acre, respectively. 
In summary, the trials showed that use of automated weeding machines were effective at controlling in-row weeds, reducing hand weeding time and that crop yield as measured by head weight was not negatively affected. Use of these machines is best suited for fields where weed pressure is high and significant labor savings can be obtained. I want to acknowledge Mosqueda et al. (2021) again for conducting these studies and sharing this information that helps growers make more informative decisions.

 
References
Mosqueda, E., Smith, R. & Fennimore, S. 2021. 2020 Evaluations of automated weeders in lettuce production. ANR Blogs.  Davis, Calif.: University of California Davis. Available at: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=45566.
¹Reference to a product or company is for specific information only and does not endorse or recommend that product or company to the exclusion of others that may be suitable.

Fig. 1. Naio Technologies Dino autonomous robot equipped with finger weeders. (Photo Credits: Naio Technologies)


Fig. 2. FarmWise Titan autonomous automated weeding machine. (Photo Credits: FarmWise)