Monday, September 11, 2017

Beetle infestation prompts tree removal

An arborist lowers a section of a dead tree in Duke Gardens.
By Sheon Wilson
Publications Coordinator

Crews are removing three pine trees in Duke Gardens' Culberson Asiatic Arboretum this week after detecting a virulent pest: the Southern pine beetle

The beetles have attacked two mature pines in Pine Clouds Mountain Stream, so arborists are removing the trees before the scourge spreads. A third vulnerable tree nearby will also be removed.
Southern pine beetle.
Photo by Marc DiGirolomo,
U.S. Forest Service

Visitors will be unable to walk through the Pine Clouds area during this work. They will be redirected with detour signs. We apologize for the inconvenience.

The work should take about three days; we will update here when it's finished. It requires taking down the trees one section at the time to avoid damaging the plants beneath. 

Southern pine beetles bore tiny holes
 into unhealthy pine trees.
During the two-year construction of the Japanese garden, which was completed in 2016, the weight of heavy equipment damaged some roots. That weakened the trees and prompted the beetles to move in. They bored tiny holes and ravaged the trees from the inside.

 “We noticed that the tops of the trees were brown; that appeared over a weekend,” said Bobby Mottern, director of horticulture. “Pine beetles are notorious for detecting trees that have been weakened.”
When pine trees are infested with Southern pine beetles,
as is the tree in the forefront, they look brown and weak.

Southern pine beetles are common, native insects. They know when a tree is stressed - by compacted soil or even drought, for instance - because the tree sends out a pheromone that the beetle detects. 

Once that happens, it’s hard to stop the beetles’ damage without fully removing the tree. Keeping trees healthy is about the only way to prevent infestations.

All photos by Sheon Wilson, except where noted.

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