Mountain pine beetle infestation hits Denver

In May, 2011, Swingle Lawn, Tree and Landscape Care warned of a mountain pine beetle infestation in Denver, Boulder and along the Colorado Front Range. “Our fears have been realized,” said Tom Tolkacz, Swingle CEO. “The mountain pine beetle is now firmly entrenched in Colorado’s most densely populated and landscaped urban and suburban areas.”

Swingle Arborists first documented the apparent migration late summer, 2010, noting pitch masses on many ornamentally grown ponderosa and Scotch pine trees. That infestation led to the 2011 death of hundreds of pine trees from Cheyenne to Fort Collins.

In Denver and its suburbs, most attacked trees remained green this season – but the clock is ticking. “These next two to three weeks,” Tolkacz advised Denver and Boulder property owners, “is an essential time to look at your pine trees. New mountain pine beetle pitch masses will become evident.” A milky gray substance will appear on the tree trunk, similar in size and shape to a popped popcorn kernel.  As other insects will also cause pines to pitch, Tolkacz recommends enlisting a professional arborist to examine trees that appear to be affected.

Many urban trees survive their first bout with beetles. “Look carefully in the pitch and you might find little black beetles drowning in the sticky goo,” said Tolkacz. “If caught early enough, the infestation can be treated and the tree saved.”

“We strongly recommend spraying your pine trees yet this year, especially ponderosa and Scotch,” said Tolkacz, who also warned that while Denver and Boulder have enjoyed an unusually wet July, complacence is an ally to the parasite. “A well hydrated tree is more likely to fend off beetle attacks. In Colorado, fall and winter can be incredibly dry. When precipitation is scant and protective snow cover is lacking, water your trees every four to six weeks.”