Your Guac Could Be In Danger: A Pesky Bug Is Killing Avocado Trees In Florida

Aug 3, 2016

It's like a scene from a movie. On one side there are bare and dead avocado trees. On the other, there are freshly planted and seemingly healthy avocado trees - some bearing the large green fruit we love to squish and turn into guacamole. 

The contrast paints a picture of the effects of laurel wilt, a fungal disease spread by the non-native Redbay ambrosia beetle. 

Mary Ostlund, a farmer at Brooks Tropicals farm in Homestead, inspects the avocado trees almost every day to check for pests.
Credit Amanda Rabines / WLRN

South Florida tropical fruit farmers have been dealing with the disease, since 2012, after the first recorded case of laurel wilt was found in a commercial avocado tree. 

Mary Ostlund, a farmer from Brooks Tropicals LLC farm in Homestead, faces the threat of laurel wilt every day. "We keep a keen eye on the trees. We look and see for any dead branches or insects,or anything that might bring this disease to our grove," she said. 

 In all, Ostlund says it takes a lot upkeep and feet-on-the-ground to keep their groves alive. 

But sometimes all the work and care are not enough to save a tree. Brooks Tropicals maintains 3,000 acres of avocado trees, but Bill Brindle, vicepresident of sales, said they have already lost nearly 30 acres to the disease. 

"It's an ongoing battle, and we're continuously re-planting those trees, so in the future our avocado groves will still be healthy and have full production," Brindle said. 

Other farmers have had to make tougher choices. 

Dead avocado trees in Homestead.
Credit Amanda Rabines / WLRN

"As far as the growers go, they're frustrated, because you don't have the cure and the answer is 'we'll just rip out your trees.' That's not a happy thought and it's a very expensive thing to do," said Jeff Wasielewski, a commercial tropical fruit extension agent for Miami-Dade County who has worked with the community for three years. 

In the meantime, the University of Florida Tropical Research and Education Center is looking for a solution to save Miami-Dade County's leading crop, which brings in $54 million a year in revenue.  

Jonathan H. Crane, a tropical fruit specialist at UF, says there are all kinds of measures farmers can take to prevent avocado trees from contracting the incurable disease in the first place. 

Protocol includes: scouting the area, trenching, completely uprooting infected trees and destroying the wood by burning or chipping the bark, and spraying or injecting fungicide into avocado trees. 

"It is hard to get ahead of the disease if you don't control it very quickly and drastically to begin with, and that has complicated everything especially the finances of it," Dr. Crane said. 

Florida International University, Miami Dade County and other national agriculture agencies are also helping to fund  research on the disease. 

Once laurel wilt takes a hold of a tree there is no cure, so many farmers in Homestead have had to kill and remove acres of avocado trees.
Credit Amanda Rabines / WLRN

"They've collaborated with us, let us use their grove trees, you know, millions of dollars of time and labor resources, so I'm pretty optimistic," said Dr. Crane. "It's going to take time, it's going to be painful, but I think we are going to do it."