Science

Avocado trees dying of fungus may be saved by drones, dogs

Dogs and drones may be the best hope to save Florida's dying avocado trees before the fungus that's killing them spreads to crops in other states, threatening the world's guacamole supply.

Asian ambrosia beetle carries laurel wilt fungus, which is deadly to avocado trees

This Miami, Fla., avocado tree has been damaged by a deadly fungus spread by the ambrosia beetle. (Tamara Lush/The Associated Press)

Dogs and drones may be the best hope for Florida avocado trees that are being threatened by a fungus-spreading beetle.

The Asian ambrosia beetle is spreading a fungus, laurel wilt, to avocado trees in Florida. Already, some 9,000 trees have been lost to the fungus, Jonathan Crane, a University of Florida professor and tropical fruit crop specialist, told CBC's As It Happens in a recent interview.

"This is no question the biggest threat to the commercial avocado industry in Florida," he says. "We have never faced anything this devastating."

The ambrosia beetle carries laurel wilt, which is deadly to avocado trees. (Tamara Lush/The Associated Press)
Florida houses about 7,500 acres of the crop, totaling about 700,000 trees. A little bit more than one per cent has succumbed to the fungus.

Wilted leaves are the first symptom, followed by dead leaves hanging on the tree.

"By the time you see that, there's nothing you can do," says Crane. A tree dies within four and eight weeks after infection.

Special cameras, dogs' noses can help

Crane believes it's possible that dogs and drones can help with early detection to give farmers the opportunity to remove infected trees before they spread the fungus to their neighbours. Both detection systems are still being developed, but Crane says they look very promising.

Laurel wilt decimated this grove of avocado trees. (Tamara Lush/The Associated Press)
Drones can take pictures of a farmer's crop with a cameras equipped with special lenses. Those lenses can detect different forms of light. They'll be able to detect if a tree is under stress before it's visible to the human eye.

Farmers can then choose to remove the infected trees or get a second opinion from a special canine unit.

Dogs can detect the disease by smell. They're trained to sit down in front of a tree that smells suspicious.

"This would allow us to stop the spread of the disease through the root system much more successfully than we are now because right now we just don't know where it is," he says.

If the fungus isn't stopped, it could spread to Texas, says Crane. From there, it's not far to Mexico and California, which have large commercial avocado industries.

"We're putting at risk, you know, a $400 million industry," he says.