Robotic weeders could be coming to a farm near to you, with the technology offering an alternative to using herbicides and hand-weeding.
Speciality crops – vegetables like lettuce, broccoli, tomatoes and onions – are just that, a speciality. They are not mass produced like corn, soybeans and wheat. A lack of available herbicides to rid the crop of weeds means that hand-weeding vast fields is necessary, but this can be expensive and time consuming. Due to labour shortages, it can cost anywhere between $150 and $300 per acre to de-weed a field.
Farmers and growers are therefore searching for an alternative, with robotic weeders emerging as the most popular.
I've been working with robotic weeders for about 10 years now, and the technology is really just starting to come into commercial use. It's really an economic incentive to consider them.
Steven Fennimore, Extension Specialist at the University of California
Fennimore has been collaborating with university scientists and companies to engineer and test the weeders. The machines use tiny blades that pop in and out to uproot the offending weed without damaging nearby crops. He says that although the technology is far from perfect, it is constantly improving.
The weeders are programmed to recognise a pattern and are capable of telling the difference between a plant and the soil. They use machine vision technology together with fast data processors to recognise crop row patterns and allow for the removal of intra-row weeds or thinning of crops to desired stands.
However, they currently have trouble telling the difference between a troublesome weed, and a crop. Fennimore explains that some companies are training the machines how to tell a lettuce plant apart from a weed. He’s also collaborating with university engineers on a system to tag the plant, so that the automated weeders will know to avoid it.
"The problem with the machines right now is that they are version 1.0, and there's tremendous room for improvement," he says. "The inability to be able to tell the difference between a weed and a crop requires the grower to be very exact when using them. The rows have to be a little straighter, cleaner, and more consistent because the machines aren't that sophisticated yet. The robots don't like surprises."
Robotic weeders currently on the market can cost anyway between $120,000 and $175,000 – for some Californian growers, it is a better long-term option to expensive and laborious hand-weeding. For others, the price tag is far too steep - it’s a lot of money to pay for new technology and instead they’d rather wait for it to improve and the price to come down.
Fennimore believes robotic weeders are the future of weeding in speciality crops. In Europe, many growers have been using the machines for some time because of high labour costs and the incentives offered to grow organic produce with fewer pesticides.
His work is now focussing on physical control of weeds because it offers the best option. Each crop will require a different weeding system, so Fennimore has also started working in crops other than lettuce, such as tomatoes and onions.
"I believe what makes the robotic weeders better than herbicides is that this electronic-based technology is very flexible and can be updated easily," he says. "We all update our phones and computers constantly, which is a sign of a robust and flexible technology."
“Investment in weed automation technology would be a win-win for everyone as it generates higher paying jobs in the crop protection industry; leads to the use of less risky weed control tactics, and promotes a more sustainable weed control system,” he concludes.