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Southern Pine Beetle Reaching Outbreak Levels In North Florida

GAINESVILLE—Southern Pine Beetle populations have exploded to outbreak levels along the Suwannee River in Hamilton and Madison counties, where the tree-killing beetle has invaded several pine plantations.

Forest owners throughout North Florida need to check their stands and begin control measures if they spot the voracious beetle, said entomologist John L. Foltz, of the University of Florida’s Institute of Food and Agricultural Sciences.

The Southern Pine Beetle can be a costly pest, Foltz said. A recent historical review showed that it caused $900 million in damage to U.S. pine forests from 1960 through 1990.

Foltz and forest entomologist James R. Meeker of the Florida Division of Forestry spotted rapidly expanding infestations of Southern Pine Beetle on several plantations of 20-year-old loblolly and slash pine in the last week of June. They recommend that all forest owners survey their property, as should homeowners who might have vulnerable loblolly pines, the beetles’ preferred hosts.

The Southern Pine Beetle is the most aggressive and destructive of five bark beetles that feed on southern pines, Foltz said. In fact, its scientific name, dendroctonus, means “tree killer.”

The most effective way to eradicate the beetle under outbreak conditions is to remove infested pines, an approach that requires the cooperation — and understanding — of an entire community. Using this approach during an outbreak in Gainesville in 1994 saved thousands of trees in the urban forest, minimized use of pesticides and saved money.

“With quick detection and quick, areawide control, overall tree mortality can be kept quite low,” Foltz said.

Tree removal, however, sometimes is misunderstood, Foltz said, and in some communities, cutting down infested pines can cause controversy.

“People sometimes have problems cutting down infested pines. The trees are still green and they have a tendency to want to try to save a tree, when actually, the tree is already dead,” Foltz said.

Leaving an infested pine in place only gives the beetles a platform for staging their attack on nearby healthy trees and can lead to the deforestation of surrounding acreage. Had Gainesville delayed in removing infested trees, Meeker said it would have been “very, very costly.”

“During outbreaks, the Southern Pine Beetle is going to run the show and will overwhelm all the pines in its path, including the more resistant slash and longleaf pines,” Meeker said. “It will not stop until it runs out of pines.”

Trees successfully colonized by the beetles cannot survive, regardless of control measures, like pesticides. The beetles also carry and introduce into trees the deadly blue stain fungi. Under normal conditions, the beetles dine only on stressed or damaged pines, but during outbreaks they attack healthy trees. Females may live a month and lay 160 eggs, allowing infestations to spread at a rate of up to 50 feet a day under the worst conditions, Meeker said.

Florida has been laying the foundation for a pine beetle attack over the last few decades, with planted acreage of loblolly pine twice what it was 30 years ago and at a higher level than in 1949, when Florida’s first forest inventory was conducted, Foltz and Meeker said. That means plenty of food for the beetle, which is partial to the taste of loblolly, and more frequent, widespread and destructive outbreaks for forest managers.

“We will probably see more and more outbreaks in the years ahead,” Foltz said. “But this is a manageable pest, if everybody works on it together. Across Florida, people need to keep an eye out for this beetle and understand the need to act quickly.”

Foltz points to an example in Texas, in which 9,000 acres of a 10,000-acre recreation area was stripped of its pines over a two-year period because of a delay in recognizing the infestation and then removing the affected trees. With the increasing acreage of mature loblolly pine in Florida, it’s a scenario foresters, farmers and communities want to avoid.

“As one of my retired colleagues has said, we’ve been setting the table for the Southern Pine Beetle,” Foltz said, “and now it has come to dinner.”

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