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Disease-carrying beetle may kill thousands of trees in Pinellas, Hillsborough

Spread by a beetle, laurel wilt is killing hundreds of trees in John Chesnut Park in East Lake near Lake Tarpon and has begun spreading into the Brooker Creek Preserve. Watch a video about the disease at links.tampabay.com.

Joseph Garnett, Jr. | Times

Spread by a beetle, laurel wilt is killing hundreds of trees in John Chesnut Park in East Lake near Lake Tarpon and has begun spreading into the Brooker Creek Preserve. Watch a video about the disease at links.tampabay.com.

A deadly menace has turned up in the Tampa Bay area, threatening to kill thousands of trees.

The exotic pest called the red bay ambrosia beetle is smaller than a grain of rice, but it's causing big problems for red bay laurel trees and their cousins, swamp bay trees and avocado trees. The beetle brings with it a ferocious, fast-spreading epidemic called laurel wilt disease. There is no cure.

Officials announced Monday that the disease is killing hundreds of trees in John Chesnut Park, near Lake Tarpon in north Pinellas County. It has begun spreading into the adjacent 8,000-acre Brooker Creek Preserve, a Pinellas gem with vast stands of trees.

The disease was recently discovered in northwestern Hillsborough County, too. Experts predict it will soon sweep through the rest of Pinellas and Hillsborough.

"This disease is very devastating. It really seems to impact every tree from those species," said Steven Harper, division director in Pinellas County's Department of Environmental Management. "Now that it's unleashed, there is unfortunately nothing we can do about it except to let it run its course."

Although it wipes out red bay laurels, swamp bays and avocado trees, laurel wilt is not a threat to other plant species, according to experts. It has not yet been found in Pasco or Hernando counties, state officials say.

Red bay laurels are somewhat common in Florida's suburban neighborhoods and are even more common in the state's hardwood forests.

"They're not planted very often as ornamental trees, but you do find them in a lot of people's yards, particularly in coastal areas. People don't notice how common they are until they all start dying," said state entomologist Jeff Eickwort, who has been tracking the disease's march through Florida.

The red bay ambrosia beetle is originally from Asia. It arrived in a Georgia port about a decade ago, probably nestled in wood used for shipping crates. It quickly spread into South Carolina and Florida, where it first appeared near Jacksonville in 2005, state records show. The pest has since spread to most Florida counties and is encroaching on multimillion-dollar avocado crops in South Florida.

"It's a serious threat to commercial avocados," said University of Florida plant pathologist Randy Ploetz. "We're on the case, but we have no good, effective answer right now."

The beetles don't actually eat the trees. They feed on a fungus that they introduce into the tree when they bore into the wood. The fungus then spreads through the wood, Eickwort said, interfering with a tree's vascular system until its leaves wilt and take on a reddish or purplish discoloration. The trees eventually die.

In John Chesnut Park, which borders Lake Tarpon's southeastern tip, a single case of laurel wilt was detected about 16 months ago, county officials said. The diseased tree was removed, but now hundreds of others are infected.

The first visible symptoms of the disease are tiny bore holes in the base of the trunk, with small strings of compacted sawdust protruding from the bark.

"They're probably about the width of a toothpick," said Pinellas County extension agent Jane Morse.

Officials recommend that you contact a certified arborist if you have concerns about trees in your yard, or contact the horticulturists at your local extension service.

First, make sure you have a red bay and not a live oak, because the trees look similar, with twisting trunks and leathery leaves. But bay leaves are slightly bigger, flat rather than spoon-shaped and, like the related bay leaves used in cooking, give off a distinct, resin-like aroma when crushed.

For a price of roughly $80 to $100 per tree, an arborist could take preventative measures to try to ward off the beetle. This involves injecting the tree with a bright blue fungicide called Alamo before the tree is infected.

"That's the only option out there that's been shown effective," Eickwort said. "But our expectation is that you have to repeat the process every couple of years pretty much forever."

Officials recommend burning, burying or shredding the infected trees. The beetles have at times "leaped" hundreds of miles, and experts think they've been brought to some counties in bundles of firewood.

"If they're able to burn it, that's ideal, but most people aren't," Eickwort said. "If you use a commercial wood chipper, the wood chips quickly become unsuitable for the beetles."

Times staff writer Dan DeWitt contributed to this report. Mike Brassfield can be reached at brassfield@tampabay.com or (727) 445-4151.

Extension services

Pinellas County Extension:

(727) 582-2100 or pinellascounty

extension.org

Hillsborough County Extension: (813) 744-5519 or hillsborough.ifas.ufl.edu

Disease-carrying beetle may kill thousands of trees in Pinellas, Hillsborough 09/17/12 [Last modified: Monday, September 17, 2012 10:52pm]

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