A Virginia Tech plant pathologist has developed autonomous unmanned aerial vehicles—sometimes called a drone—to detect airborne pathogens above agricultural fields.

David Schmale, an assistant professor of plant pathology in Blackburg, has given scientists an unprecedented glimpse into the life of microorganisms hundreds of meters above the surface of the earth.

"Until recently, researchers used autonomous UAVs for military applications, but now we can apply this cutting-edge technology to agriculture," Schmale says.

Scientists have used aircraft to monitor the movement of airborne pathogens for years, but Schmale is the first plant pathologist to use an autonomous system for this process.

"Autonomous UAVs have distinct advantages over a sampling aircraft operated via remote control," Schmale says. "First, the autonomous UAVs maintain a very precise sampling path. We can establish a GPS waypoint in the center of an agricultural field, and the autonomous plane can circle around the waypoint at a set altitude, with about a meter variation up and down. Second, the autonomous technology enables us to have coordinated flight with multiple aircraft. In other words, we can have two aircraft sampling pathogens at the same time but at different altitudes."

Schmale has used the small, self-controlled planes to collect samples of the fungal genus Fusarium tens to hundreds of meters above the surface of the earth. This genus contains some of the world's most devastating plant and animal pathogens and remains largely a mystery to scientists.

By placing antibiotics in the sampling collection plates, researchers can ensure that only Fusarium will grow on the plates. Over the course of 75 different UAV-sampling flights above agricultural fiends at Virginia Tech's Kentland Farm, Schmale and his colleagues collected more than 500 viable colonies of Fusarium, representing at least a dozen species.

"For 11 of these Fusarium species, this is the first report of their ability to be transported great distances above the surface of the earth," Schmale says. "Our work has important implications for the rapid spread of invasive plant and animal pathogens in the United States."

Schmale's research is not limited to the study of Fusarium, however. He has expanded his interests to explore entire microbial populations in the atmosphere—a type of research he calls "aerogenomics."

"One of the species we collected with our autonomous UAVs appears to be a bacterium known only to exist in a cavern in Arizona," he says. "What was that bacterium doing 100 meters above Kentland Farm? In many of our other samples, we have found organisms that have never been cultured before. Some of these microbes may thrive only in the atmosphere, and many of them may be new to science."

Although Schmale is not conducting his research for the armed forces, his work has a definite biosecurity element.

"Many plant pathogens are transported over long distances in the atmosphere, threatening agriculture in the United States from both inside and outside the borders of the country,? Schmale says. "An increased understanding of the dynamics of plant pathogens in the atmosphere is essential for establishing effective quarantine measures, preventing the spread of plant disease, and mitigating potentially damaging events targeted at our nation's agriculture and food supply."