May 2008

Aerial research could help farmers combat plant pathogens

By Kathy Dixon

Phytophthora infestans does to potato and tomato plants what a bucket of water did to the Wicked Witch of the West—it melts them.

But with help from cutting-edge research at Virginia Tech, potato and tomato producers might soon be able to better manage this high-risk pathogen that was responsible for the Irish Potato Famine and led to the starvation of millions in the 1800s.

“Our goal is to provide a means to predict, monitor and forecast high-risk plant pathogens,” said Dr. David Schmale, assistant professor of plant pathology, physiology and weed science in Virginia Tech’s College of Agriculture and Life Sciences.

He and two other researchers were granted almost $1 million from the U.S. Department of Agriculture National Research Initiative to study how P. infestans is transported through the atmosphere, using unmanned aerial vehicles—or UAVS—over the next three years. Dr. Elson Shields, an entomology professor at Cornell University, and Dr. Donald Aylor, a distinguished agricultural scientist at the Connecticut Agricultural Experiment Station, are collaborating with Schmale on the project.

P. infestans, as the pathogen is routinely called, is a fungus-like organism that is considered a plant biosecurity threat in the United States. It causes late blight disease in potatoes and tomatoes and in just a few short days can destroy an entire field of vegetables.

The last major outbreak in Virginia was in 1996 on the Eastern Shore. “It was a widespread epidemic, and no one knew what to do,” Schmale said. “In many of the affected fields, it was too late for chemical applications to manage the disease.”

There are currently no commercial varieties of potato that are completely resistant to the pathogen. Therefore, growers need to be prepared to respond to an outbreak in short order.

Tracking the movement of P. infestans in the atmosphere should help growers do that. “Our UAVs can track the movement of a plant pathogen through the atmosphere tens to hundreds of meters above the ground,” Schmale said. “Using cutting-edge DNA-based methodologies, we can identify the pathogen in a matter of minutes.

“If growers catch this before the epidemic starts, we hope that the problem can be nipped in the bud.”

Schmale and his team of technical staff and students operate nine planes in their UAV fleet. The planes come in an almost-ready-to-fly hobby kit and are assembled in a laboratory in Latham Hall, explained John Cianchetti, senior lab and research specialist.

Once all the basic parts have been assembled, the planes are fitted with various electronics, including a GPS and an autopilot that’s about the size of a cell phone. One or more GPS points are uploaded into the autopilot, and the plane flies a specific pattern and altitude over a field. “We can flick a single switch, and the aircraft flies itself after it’s programmed,” Cianchetti said.

Samplers are mounted on the front of the wings, and inside each is a collection plate. While in the air, the samplers open and the plates collect spores of plant pathogens like a car grill collects dead bugs.

The planes fly in repeating patterns, the data is analyzed, and the results are recorded and then provide the data for a future model that will assist in forecasting late blight epidemics.

“This will enhance the nation’s agricultural security by providing producers with new tools that will enable them to react based on science and make better management decisions,” Schmale said.

Previous research using the UAVs has tracked the movement of a pathogen of wheat, barley and corn. The fungus Gibberella zeae produces a deadly toxin that can cause humans and animals who consume the grains to become ill, Schmale said.