In vegetable production, growers cultivate most of the bed leaving only a 4-inch wide uncultivated band around the seedline. Weeds not controlled by preemergent herbicides or cultural practices in the uncultivated band are ultimately controlled by hand. Labor costs have increased and availability has decreased in the last 4 – 5 years which has spurred grower interest in automated weeder technology. In the last two to three years, automated weeders have become available in the Salinas Valley. All current machines were developed and manufactured in Europe: the Robovator developed in Denmark by Poulsen Engineering and distributed by Pacific Ag Rentals (Salinas); the Steketee IC developed in the Netherlands and distributed by Sutton Ag (Salinas); and the Garford developed in England and distributed by Quinn Tractor (Salinas). The Robovator and Steketee machines use a split blade that comes together between crop plants to take out weeds and opens as it passes the crop plants (keeper plants). The Garford machine uses a spinning blade with a notch which places the keeper plant in the notch and spins around it.
Steketee IC cultivating three 80-inch wide beds
The same basic technology is used by each of these machines: 1) a camera to detect the crop, 2) a computer to make decisions on which plants to keep/remove and 3) a kill mechanism. They were originally designed for use on transplants. The use of transplants makes distinguishing the crop from the weeds initially easier when the transplant is larger than young weed seedlings. An island of uncultivated soil is left around the keeper plants for safety, but some weeds can survive in this buffer area. We conducted trials the first year that these machines were available in the Salinas Valley and observed that automated weeders removed about 51% of the weeds in the seedline and reduced subsequent hand weeding time by 37%. However, growers that have experience with the machines, say that with time and experience, they are getting better results.
Uncultivated buffer area around a keeper plant
There is a great deal of interest in developing automated weeders for use in vegetable crops. Innovations that are being developed include: 1) the use of deep learning to train computers to better distinguish crop plants from weeds; 2) use of spray kill mechanism that can allow for pin point application of herbicides (e.g. Seek & Spray, Blue River Technologies); and 3) autonomous weeders (e.g. Naio, France; AgBot, Australia; Anatis, France; FarmWise, San Francisco, CA). A quick search on YouTube will reveal a large number of autoweeding concepts that are being developed in many parts of the world. One interesting concept is a solar powered autonomous weeder, EcoRobotix (Switzerland), that removes weeds from the seedline by applying a micro-dose of herbicide.
At present, the automated weeders are quite expensive and are only affordable by larger operations. However, one company is offering monthly rentals of their machine, which allows growers to try out the technology before making a large investment, as well as making the technology accessible to smaller growers. Considering we are still in the early stages of the development of this technology, it will be fascinating to watch its adoption and progress as time moves forward.