For many years, Pioneer and Drake Parks have been home to several species of trees, providing shade and beauty to park users. Now, two tree species in the parks, black locusts and silver maples, are under siege by borers and rot, a common problem across the United States for both species.
The infestation is requiring Bend Park & Recreation District to strategically prune and, in some cases, remove and replant trees. Tree removal is planned for Tuesday, park officials announced Monday.
Park district Marketing Manager Colleen McNally said four trees at Drake Park and about 12 at Pioneer Park are expected to need removal. An arborist will reassess the damage as they work on the trees and determine how extensive the infestations are, she said.
“Unfortunately, the severely affected trees need to be removed due to weakened branches and trunks which create a safety hazard for park amenities and visitors,” said Sasha Sulia, the park district's natural resources manager.
“Eventually the trees will die from the infestation or disease. Working with a certified arborist, the district is taking steps to manage the trees as best we can but sometimes a tree is too diseased and needs to be replaced with a better species for our region.”
At Pioneer Park, there are 35 black locust (Robinia pseudoacacia L.) trees planted throughout the park. Native to the eastern United States, these deciduous trees are estimated to be 70 to 80 years old.
Under normal conditions, black locust trees live an average of 60 years and a maximum of 100 years. Specific only to black locust trees, locust borers larvae tunnel into a tree’s trunk and branches and over time cause serious damage and/or tree mortality.
“For several years, locust borers have infested all of the black locust trees within Pioneer Park,” said Sulia. “The borer’s damage is evident in the multiple dead branches, leaf dieback and boring dust on the tree boles.”
At Drake Park, similar problems exist with several trees along Riverside Boulevard. One tree is a black locust experiencing a severe locust borer infestation similar the trees in Pioneer Park.
The other affected trees are silver maples (Acer saccharinum) and are diseased with extensive bole rot. Native to the eastern United States, silver maples have very soft wood, making them susceptible to different rot-causing fungi.
The affected trees in the two parks were assessed last summer by a certified arborist to determine the extent of the locust borer and bole rot damage. The assessment was incorporated by the district in its management plan for the trees. The plan includes pesticide spraying, tree pruning, removal and replanting with non-host trees.
The parks will be replanted with a non-host tree species this spring. The 23 black locust trees that remain in Pioneer Park will be treated with pesticide in attempt to reduce the locust borer population.
Through pruning and treatment, the district says it hopes the remaining black locust trees will survive. Continual arborist assessments of these trees will determine if they remain healthy enough to retain or will need to be removed.
For additional information on the tree work, visit www.bendparksandrec.org or contact Sasha Sulia, BPRD Natural Resources Manager, (541) 706-6203 or firstname.lastname@example.org.