Sniff, sniff. The dog nose knows. Scientists have long understood that canine snouts are among the world’s best. God made dogs able to smell everything from bedbugs and DVD plastic to diabetes and emotions. New research suggests doggie scent detectives could help save fruit trees too.
Scientists at the U.S. Department of Agriculture are training dogs to sniff out a crop disease called “citrus greening.” Tiny insects feed on the leaves and stems of citrus trees and spread the citrus greening bacteria. The blight has hit orange, lemon, and grapefruit groves in Florida, California, Louisiana, and Texas. Citrus greening has also affected Central and South America and Asia.
There’s only one way to stop the spread of citrus greening: Growers must remove infected trees before the disease spreads. Catching the bacteria that cause citrus greening is key, since the disease can spread before trees ever show symptoms.
Finding something that isn’t visible is difficult for humans. But trained dogs can detect the fruit disease weeks—or even years—before it shows up on tree leaves and roots.
“This technology is thousands of years old—the dog’s nose,” says Timothy Gottwald, a researcher with the USDA and a co-author of the study. “We’ve just trained dogs to hunt new prey: the bacteria that [cause] a very damaging crop disease.”
A study for the National Academy of Sciences showed that dog sleuths are faster, cheaper, and more correct than humans. After all, humans must collect hundreds of specimens and analyze them one at a time.
“The earlier you detect a disease, the better chance you have at stopping an epidemic” by removing infected trees, explains Gottwald.
In one test, trained dogs in a Texas grapefruit orchard had a 95% success rate. The canine sniffers could tell the difference between newly infected trees and healthy ones. In another study, the dogs were over 99% accurate!
Researchers took steps to be sure the dogs were smelling the citrus greening bacteria and not another bacterium or infection. Amazingly, no matter how scientists mixed things up—roots only, non-citrus plants, different kinds of diseases, multiple diseases—the dogs identified the citrus greening disease every time.
“You’ve seen dogs working in airports, detecting drugs and explosives,” says Gottwald. “Maybe soon you will see them working on more farms.” How does “Farmer Fido” sound?