Florida avocado growers are continuing their nearly two-decade-long battle with the destructive laurel wilt disease.
The disease has shown up in each of Florida’s 67 counties, said Jeff Wasielewski, commercial tropical fruit extension agent for the University of Florida’s Institute of Food and Agricultural Sciences Extension, Miami-Dade County, in Homestead.
More than 300,000 avocado trees have been lost in Miami-Dade County since the disease appeared there in 2011, Wasielewski said. He estimated the economic impact to the region’s economy at $54 million.
It’s spread by tiny ambrosia beetles, and though it affects several kinds of trees, avocados are the only fruit affected.
“The tree will begin to wilt in one section and move to the next,” Wasielewski said. “Leaves on the entire tree will eventually die and turn brown.”
There are a few tools available that growers can use to combat laurel wilt.
“Some growers inject fungicide to protect the trees from LW, but this is costly and time consuming,” he said. “They can also spray to knock down the beetle populations.”
He advises growers to keep trees well pruned and open to light and air, since beetles prefer shade, and a well-pruned tree will be less attractive to them.
The University of Florida and the private sector, including some major growers, are looking for ways to cope with laurel wilt disease.
“UF is currently testing hundreds of young avocados that are different varieties and different rootstocks, including some from California,” he said. “The hope is that some of the trees will be resistant to LW.”
Wasielewski said he doubts that the disease will ever be wiped out in Florida, but he doesn’t expect it to get any worse.
“Trees will continue to die, but growers are very resilient and have already planted thousands of young avocados to take the place of trees that were lost,” he said. “Younger trees are not attractive to the beetles and can grow and produce for many years before they are in danger of getting LW.”
