Researchers are currently testing a semi-automatic drone spray system guided by global positioning system (GPS) coordinates fed into the drone's flight planner. They found that the drone could hover over the target area with an accuracy of 1-2 feet, improving the precision and safety of herbicide applications. But before the system can be widely used in agriculture, the researchers say it is important to know more about spray drift patterns, the impact of droplet size and the environmental and health effects of uav-based herbicides. This information is critical to the EPA as it works to develop policies to address acceptable drone use patterns, herbicide labeling, and regulatory, safety and enforcement issues. But those who study drones as a weed control tool are optimistic about the potential. With the right computer processing power and battery life, unmanned aircraft may one day be completely autonomous -- able to identify weeds in real time and apply site-specific herbicides, all of which are part of a sustainable, site-specific weed management system. "It's easy to imagine early response plans to spot potentially resistant weeds that have been previously treated," says Muthu Bagavathiannan, a weed scientist at Texas a&m university. "This can greatly improve weed control and reduce the supply of weed seed Banks, as well as reduce the use of herbicides."