The future of weed control

In integrated weed management, farmers employ a diversity of weed-killing techniques, including tillage, cultural practices, and methods for depleting the weed seed bank, rather than depending solely on the spraying of Roundup or another single tool.

But diversification isn’t the same as true integration, cautions University of Nebraska-Lincoln weed ecologist, Steve Young. Why? Because most integrated weed management practices still manage every weed the same, regardless of location or season, and they’re usually deployed one at a time rather than together. Young is now hoping to change that by developing a fundamentally different approach to weed control.

In the automated systems he envisions, sensor and computer technologies onboard a tractor would first categorize each plant in a farmer’s field as either weed or crop, and then go on to identify the species of weed. Once those identifications were made, one of several weed fighting tools located on the tractor could be applied to individual plants based on their biology. If the system identified a weed that’s resistant to Roundup, for example, it could be sprayed with a different herbicide. Or an onboard cutting or flaming tool could be used to kill the plant instead.

In other words, the system could target different weed-killers to specific weeds, Young says—similar to how variable rates of nitrogen are applied in different sections of fields today based on variations in crop nitrogen status.

“This is all about trying to get more precise with our weed control practices,” Young says, and in fact he began developing his ideas while working as a postdoc at the Center for Precision Agricultural Systems at Washington State University. His advisor, Fran Pierce, was “really into automation,” he says, and it got Young thinking about ways to apply automation and robotics in weed science, as well.

Young has since been studying the micro-rates of chemicals and mechanical treatments needed to kill single plants. “If we can figure out these parameters, then they’ll be ready for the engineering part of it,” he says.

As with other precision agriculture technologies, there could be many benefits. Applying micro-doses of herbicide to the leaves of single plants would eliminate spray drift and the leaching of chemicals into groundwater. Weeds would also be less likely to evolve resistance to herbicides, because less chemical would be required overall and only targeted weeds would receive the dose.