Trees face a deadly new pest in Pierce County, including at popular park

Yahoo

2 days ago

A damaging beetle species continues to be found in Pierce County, raising concerns for pine trees at Chambers Creek Regional Park.
Jessica Stone, a natural lands steward and arborist for Pierce County, said she first noticed trees dying at Chambers Creek Regional Park around February 2024, when she came across a patch of pine trees that were turning brown. After surveying the problem, the county identified a California fivespines ips (CFI) outbreak and removed around 100 trees that had been infected last spring, she said.
While this outbreak raised concerns, the county has continued to monitor the area — early this year, a new CFI outbreak was discovered in a patch of 18 pine trees next to the Playground by the Sound in the north meadow area of the park, Stone said.
All 18 trees — which included ponderosa pine, scotch pine, black pine and shore pine — were removed on Wednesday.
Stone added that CFI infestations create small holes in the trees that are difficult to spot, and said the beetles pose no danger to humans. The playground at Chambers Creek Regional Park remained open during the tree removal process, she said.
'You would never notice,' she said about the beetles. 'The only reason I was able to even find one is that we cut into a dead tree.'
According to the Washington State Department of Natural Resources, California fivespined ips is a type of bark beetle traditionally native to California and Oregon — in 2010, they were first recorded in the state of Washington, and since then, outbreaks have continued to crop up, especially toward Eastern Washington. CFI were first recorded to be killing pines in Western Washington in July 2022, when a deadly infestation was found in ponderosa pines at Joint Base Lewis-McChord (JBLM) in Pierce County, according to the state DNR.
Rather than being invasive, CFI appear to be expanding upon their existing native territories in California and Oregon, said Todd Murray, an entomologist and director of the Puyallup Research and Extension Center at Washington State University. They focus on attacking and reproducing in pine trees specifically, he added.
Murray, who is working with Pierce County to study the CFI outbreak, said when bark beetle outbreaks occur, it can be an indicator of overall forest health, adding the beetles can more easily overwhelm trees suffering from drought or other stress.
Although it is unfortunate to have to remove more trees at Chambers Creek, the relatively small size of the latest outbreak is a positive sign, Stone said.
'It's a good sign that we don't have what we were seeing last year,' she said. 'So going from a high of over 100 to 18 is phenomenal.'
Henry Adams, an associate professor in the School of the Environment at WSU, said WSU has partnered with the DNR to monitor outbreaks of CFI across Washington, and added that this year, the amount of trees killed in those infestations has been significantly less than that of the previous year, although it is difficult to provide an estimate of the amount of trees affected.
Adams, who has also worked with Pierce County to track the infestations, said bark beetles can be identified by their Y-shaped carvings below the outer layer of tree bark, and added that their holes may also be visible, although those exit and entry points may be difficult to tell apart from another insect's. The beetles also tend to attack larger trees that can offer more phloem — the inner bark that transports sugars and other materials throughout the tree — for their larvae to feed off of, and might leave smaller trees be, he added.
Heat stress doesn't often appear immediately in trees, Stone said, adding that it can take a couple years after an event such as a heatwave to see the effects on a forest. She said these outbreaks could be indicative of stress the trees endured a couple summers ago.
Although the researchers have largely been working in parks, pine trees on private property have also been found to have CFI infestations, Adams added. He said residents should avoid leaving broken tree branches or wood chippings scattered around their yards because they can attract beetles. He added that ensuring trees are properly watered can also help ward off the insects, as the water may help pine trees produce resin that they can use to defend themselves at the site of CFI attacks.
Wary of future outbreaks, the county is also working to implement preventative measures to support tree health and ward off CFI, Stone said. The county has tried using insecticides to fend off the beetles, but found them ineffective, Stone said. They now focus on promoting the right conditions to support healthy trees.
Stone said the county plans to plant new trees in the park following the removal of the infested group, although researchers will evaluate the park's space to plan for increased diversity of tree species and larger spacing to avoid overcrowding, both of which can help deter future outbreaks and promote forest health. Following those decisions, new trees may not be planted in the same spot as the removal, but elsewhere in the park, she added.
The trees felled on Wednesday will be turned into wood chips, baked in the sun to rid them of beetles, and then used as mulch to help keep moisture in the ground around other trees in the area, Stone said.
'It's keeping our trees healthy, keeping them well-pruned, making sure we don't have a bunch of dead branches hanging around that might attract ips, or stressed, broken branches, which might attract the ips — so good tree hygiene and good tree care,' Stone said.