NASA Helps Spot Wine Grape Disease From Skies Above California

In a case study, scientists detected the costly infection in cabernet sauvignon grapevines before they showed symptoms visible to the human eye.

Withering molds, root-rotting bacteria, viruses, and other plant pathogens destroy an estimated 15% to 30% of global harvests every year. Early detection can make the difference between a failed crop and a treatable one.

Using an airborne science instrument developed at NASA's Jet Propulsion Laboratory in Southern California, researchers have found that they can accurately spot the stealthy signs of a grape disease that inflicts billions of dollars in annual crop damage. The remote sensing technique could aid ground-based monitoring for this and other crops.

In a pair of new studies, researchers from JPL and Cornell University focused on a viral disease called GLRaV-3 (short for grapevine leafroll-associated virus complex 3). Primarily spread by insects, GLRaV-3 reduces yields and sours developing fruit, costing the U.S. wine and grape industry some $3 billion in damage and losses annually. It typically is detected by labor-intensive vine-by-vine scouting and expensive molecular testing. The first study is published in Phytopathology.

The research team wanted to see if they could help growers identify GLRaV-3 infections early and from the air by using machine learning and NASA's next-generation Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS-NG). The instrument's optical sensor, which records the interaction of sunlight with chemical bonds, has been used to measure and monitor hazards such as wildfires, oil spills, greenhouse gases, and air pollution associated with volcanic eruptions.

It was during a 2020 campaign to map methane leaks in California that plant pathologist Dr. Katie Gold and her team seized the opportunity to pose a different question: Could AVIRIS-NG uncover undercover crop infection in one of the state's most important grape-producing regions?

"Like humans, sick plants may not exhibit outward symptoms right away, making early detection the greatest challenge facing growers," said Gold, an assistant professor at Cornell University and senior author of the new studies. In the case of grapevine leafroll virus, it can take up to a year before a vine betrays the telltale signs of infection, such as discolored foliage and stunted fruit. However, on the cellular level, stress is well underway before then, changing how sunlight interacts with plant tissue.