Monday, August 2, 2010

Oak Wilt Still Causing Concern

The Pittsburgh Parks Conservancy and the Pittsburgh Public Works Department are trying to keep one step ahead of the fungus known as Oak Wilt. The fungus attacks and eventually kills oak tress. The green leaves of a tree will dry up and fall off in the summer. The disease can kill some trees in a single season while other trees can hang on for a few years. Earlier this year the city removed about two acres of oak trees from Frick Park and a small group of trees in Highland Park in an effort to stop the spread. Department of Public Works Deputy Director Mike Gable says the fungus usually spreads from one tree’s roots to another tree’s roots where they touch underground. Sap beetles can also spread the disease from tree to tree. Along with removing the infected trees, city crews harvested some healthy trees to create a buffer zone and then dug trenches to keep roots from spreading. Gable says the city has seen signs of oak wilt in Frick Park and Highland Park and are keeping an eye on the trees to see if tree removal and trenching is warranted. It is unclear if the spread of the fungus can be stopped. A recent tree inventory found about 20% of the trees in the city are oaks of one kind or another, with the most common being the pin oak. Gable says he does not know how many trees on private land may be impacted. He says home owners should keep an eye on their oaks and should not trim the trees between April and October. He says cutting a tree creates an easy pathway for a bug carrying the fungus to infect the tree. The Pittsburgh Parks Conservancy will hold a class on oak wilt this Saturday at 9:00am at the Pool Grove Shelter in Highland Park.

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