BANGOR, Maine -- An invasive insect that can devastate red pine trees has been detected in at least three Maine counties and there is concern that it will eventually spread to Penobscot County and Bangor, according to the City's Forestry Division. 

Red pine scale (RPS) is a scale insect native to Asia that is believed to have been introduced to the U.S. in the 1930s. It feeds on nutrients in red pine trees by inserting their sucking mouthparts into the upper branches and twigs. This feeding interrupts the flow of nutrients and water to the needles of the trees, leading to canopy decline and eventual death. RPS was first detected in Maine in Hancock County on Mount Desert Island in 2014. Since then, it has also been found in Washington County and York County. Over 1,800 acres of red pine mortality have been detected by the Maine Forest Service and are directly attributed to RPS.

The City of Bangor has 131 red pine street and park trees. These trees will continue to be monitored for signs and symptoms of RPS; however, they are of relatively low concern because they are a low percentage of the urban canopy. What is of greater concern are the thousands of red pine trees planted in plantations across the City’s publicly owned properties and parks in Bangor and Winterport. These are monocultures of red pine that are highly susceptible to RPS infestations and much more difficult to monitor on a regular basis. Additionally, because of the density of the plantings and closure of the forest canopy, in most of these plantations there is little to no tree regeneration growing underneath to succeed the overstory red pine trees.

Chemical treatment of publicly owned red pine is not a viable option for managing RPS in the City. For this reason, active management through invasive plant management, thinning, harvesting and replanting these red pine plantations is the chosen course of action. Invasive plant management will occur first and involve the use of mechanical, cultural and chemical controls. 

This will be followed by a pre-commercial thinning of the red pine, where the least successful trees are removed to allow the remaining red pine to maximize their growth, and promote natural regeneration of other tree species. This management will reduce wildfire risks, increase forest species and age diversity, and improve wildlife habitat. A final harvest of the remaining red pine will be performed once RPS is detected in Winterport or Bangor. 

Spacing out the removal of red pine in these plantations will give the more successful trees the opportunity to increase in size so that they are more likely to be merchantable by the time they are harvested. If adequate regeneration of native tree species isn’t achieved by the time the final harvest is completed, replanting the areas with seedlings may be necessary. Appropriate species for the soil types and other environmental conditions will be selected.

For more information, contact: 
Sophia Cameron
Forest Technician
City of Bangor
207-992-4504
sophia.cameron@bangormaine.gov

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The City of Bangor, Maine, is a service center community of 31,753 residents and is the county seat of Penobscot County. Bangor is the major commercial and cultural center for much of northern and eastern Maine. The City is an equal opportunity employer and service provider. For information on City projects and news, see www.bangormaine.gov