In this interview with Boulder News, Kevin Marks, assistant district manager of Davey's Boulder office, tells homeowners how they can identify Kermes scale in their trees.
Posted: Dec. 17, 2014
By Joe Rubino
Broadway will be narrowed to two lanes Thursday and Friday in north Boulder while crews take down two red oak trees afflicted by the rare "drippy blight" disease.
The oaks, each with diameters greater than 25 inches, are on a narrow strip of city right-of-way near 3004 Broadway, just south of the Shell gas station.
Both northbound lanes will be shut down from 9 a.m. to about 3:30 p.m. Thursday and Friday in the area during the work, which will require a crane, officials say.
During the removal, and pruning of two other oaks nearby, all northbound traffic will be moved into one of the two southbound lanes.
City Forester Kathleen Alexander said the two trees being cut down are dying because of the insect- and bacteria-induced illness. A large number of dead branches hanging over Broadway presented a risk to public safety, she said.
"They have been declining for a while, but this year they really seemed to take a turn for the worse," she said, adding that drippy blight seems to have been very active in 2014.
The disease is driven by infestation of the Kermes scale insect and the associated Brenneria bacteria, said professor Whitney Cranshaw, an entomologist at Colorado State University. The disease can be identified through branches in the canopy dying at their tips, though leaves may still grower farther down, he said.
Cranshaw and CSU colleague Ned Tisserat worked with Boulder officials in 2010 when three large red oaks near the Central Park bandshell were diagnosed with the illness. It was also the first time Brenneria was officially confirmed in a red oak tree.
Drippy blight has only been found in red oaks in Boulder, parts of Denver, Spain and in California, where it only affects the nuts, according to Cranshaw.
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