Laser and robotic weeding

In plain language

Weeds compete with crops for light, water and nutrients. For decades most farms have controlled them by spraying whole fields with herbicide. Robotic weeders try to act only where a weed is. A camera on a moving machine recognises plants, and then a laser pulse, a small targeted spray or a mechanical tool removes each weed.

The evidence so far comes mainly from small field trials. In 2024 trials in New Jersey and New York on peas, spinach and beet, a laser weeder reduced weed biomass by at least 97% by the end of the season. The same trial found the laser slow, and it worked best on young weeds. Targeted spray systems such as John Deere's See & Spray have reduced herbicide use in university trials, but the amount saved depends heavily on how many weeds are present when the spray is applied.

Technical explanation

Robotic weeders usually pair a camera and a vision model with an actuator that acts on each detected plant. Laser systems deliver a short, high-energy pulse to the growing point of a weed, causing localised thermal damage. The laser weeder used in the 2024 New Jersey and New York trials was an autonomous research and demonstration unit donated by Carbon Robotics. It had 12 high-resolution cameras and eight modules, each with a 150 W CO2 laser. The manufacturer decommissioned that unit in January 2025. Gao and colleagues (2026) report that laser efficacy and energy efficiency decline for larger weeds, beyond the cotyledon to two-leaf stage.

Herbicide reduction figures measure different things, so they are not directly comparable. Iowa State University reported that a See & Spray Ultimate reduced the area treated with herbicide in the post-emergence pass by 76% on average across five soybean fields totalling 415 acres in 2024, with individual fields from 43.9% to 90.6%. A University of Arkansas three-year soybean trial reported reductions of 43% to 59% compared with broadcast spraying. Those savings came at low sensitivity settings, which increased pigweed populations, and the lead researcher recommends the high-sensitivity setting in most scenarios.

Mechanical weeding follows a different pattern. In a review of robotic weeding, the Robovator intelligent cultivator removed 18% to 41% more weeds than a standard cultivator in broccoli and transplanted lettuce under moderate to high weed densities, and reduced hand-weeding time by 20% to 45%. It did this without lowering crop stand or marketable yield. Wet, compacted, stony or residue-covered soil reduces the stability and accuracy of mechanical tools.

What the evidence says

Each statement is typed by the strength of its evidence and linked to the source that supports it.

Limitations and open problems

• Independent laser data are thin. The main peer-reviewed trial covers one 2024 season at two sites, used one demonstration unit that the manufacturer later decommissioned, and was not designed to collect economic data.
• Laser weeding works best on seedlings. Efficacy falls for larger weeds, and the trial authors reported that dense infestations above 100 plants per square metre require reduced driving speeds.
• Speed is a practical barrier. The laser unit needed 4 to 17 minutes to treat a 30.5 metre row, compared with 15 to 30 seconds for conventional herbicide application.
• Control falls at later timings. In New Jersey peas, lambsquarters control dropped from 95% one week after the second pass to 83% two weeks after, because new seedlings emerged.
• Herbicide savings are not guaranteed. Iowa State notes that savings are directly influenced by initial weed pressure and residual herbicide control, and that reductions are not guaranteed. The Arkansas reductions came at low sensitivity settings, which increased Palmer amaranth populations by 280% each year.
• Cost is significant. The trial authors estimate a minimum of $500,000 per unit.

Possible future uses

Timeline

1. 2024Cornell AgriTech and Rutgers run field trials of a Carbon Robotics laser weeder on peas, spinach and beet in New York and New Jersey. Sources: [1]
2. 22 Aug 2024Iowa State University publishes results of a 2024 five-field See & Spray trial in soybeans. Sources: [3]
3. Jan 2025Carbon Robotics decommissions the demonstration laser weeder used in the trial. Sources: [1]
4. 10 Mar 2025University of Arkansas publishes results of a three-year See & Spray soybean trial. Sources: [4]
5. 24 Jun 2025Pest Management Science publishes the New Jersey and New York laser weeding trial. Sources: [1]
6. 7 May 2026Sensors publishes a review of robotic weeding methods, including laser and mechanical systems. Sources: [2]

Futures this could help bring about

How far away?

Farming with far fewer chemical pesticides

Pilots · 4 of 8 steps done

Glossary

Broadcast spraying

Spraying an entire field evenly, rather than only where weeds are present.

Post-emergence herbicide

A herbicide applied after the crop and weeds have come up through the soil.

Cotyledon

The first leaf, or pair of seed leaves, that a seedling forms before its true leaves appear.

Weed biomass

The dry weight of weed plant material, used as a measure of how much weed growth remains.

Sources

1. peer reviewed paper
   Deep learning-based laser weed control compared to conventional herbicide application across three vegetable production systems
   Lynn M. Sosnoskie, Kylie Bill, Aleah Butler-Jones et al.. Pest Management Science, 24 Jun 2025. DOI: 10.1002/ps.8912. Accessed 21 Oct 2026.
2. review article
   A Review of Robotic Weeding Modalities for Site-Specific Weed Management
   Feng Gao, Shugui Ding, Wenpeng Zhu et al.. Sensors, 7 May 2026. DOI: 10.3390/s26102925. Accessed 21 Oct 2026.
3. other
   Precision Spraying Technology
   Doug Houser, Matt Darr, Ryan Huffman. Integrated Crop Management News, Iowa State University Extension and Outreach, 22 Aug 2024. Accessed 21 Oct 2026.
4. university press release
   Precision agriculture research measures effectiveness of See & Spray technology
   John Lovett. University of Arkansas System Division of Agriculture, 10 Mar 2025. Accessed 21 Oct 2026.

Revision history

3 changes since this profile was created.