Precision offset spray system for roadway shoulder weed control

A precision offset spray system was developed for use by highway maintenance departments for the control of unwanted vegetation in the graded shoulder area adjacent to roadways. The offset sprayer consisted of two fundamental elements: (1) A machine vision system; and (2) a rapid response intermittent spray system. This study showed that it is feasible to use machine vision on a moving vehicle to automatically detect the presence of green plant material and to apply herbicides exclusively to plants and not to nonplant materials (e.g., bare soil). The system substantially reduced the amount of herbicide applied to nonplant material. In system tests, there was up to a 97% reduction in applied splay mix over conventional continuous spray applications with a plant deposition rate of 57% of continuous spray systems. Implementation of this technology would allow highway maintenance departments to reduce the cost of weed control and the amount of chemical herbicides released into the environment, while maintaining current levels of weed control efficacy.