SHERIDAN — A recently-detected tree pest could pose a threat to public and private pine trees in and around Sheridan, city arborist Clark Van Hoosier cautions local residents.

Van Hoosier said Colorado State University’s Plant Diagnostic Clinic confirmed Pine Wilt Disease has made its way to the Sheridan area after analyzing a sample from a local tree last week.

The disease is native to North America — though not to Wyoming — and therefore does not impact native North American trees, such as ponderosa, limber, bristlecone or whitebark pines, spruce or fir trees. It is fast-acting and lethal in non-native species, however, such as scots pines, Austrian pines and mugo pines.

“All three of those species — there aren’t a whole lot of them around (Sheridan), but the ones that are around are big and old typically,” Van Hoosier said.

Van Hoosier said there are several areas in Sheridan County where scots pines were planted in rows to act as wind breaks, for instance, but the trees can also be found on private property.

“The biggest thing to stress to people is knowing what trees you have on your property,” Van Hoosier said. “If you don’t know, get someone qualified to come and take a look at them.”

He added that he and his staff are willing to assess trees on private properties within Sheridan’s city limits.

“With that being said, the city forestry program is me and one other guy, so we’re definitely understaffed,” Van Hoosier said. “But we want to be as much of a resource as we can.”

Sheridan is the second Wyoming city with a confirmed case of Pine Wilt Disease; it emerged in Cheyenne last year.

Wyoming State Forestry Division District Five Forester Kelly Norris, whose office is in Buffalo, said there is also a possible case of the disease in Gillette, though it has not been confirmed as of Thursday.

The fact that the disease has now presented itself in multiple Wyoming communities is cause to be on the lookout, though, Norris said.

“If it’s getting confirmed in a community like Sheridan and a community like Cheyenne, it is most likely in other communities across Wyoming,” Norris said. “…We want to educate and do outreach so we have a better idea of where this is located across the state. That would be our biggest concern — how far has this spread and what communities are being affected?”

The nematode that causes the disease gets transported from tree to tree by pine sawyer beetles, which emerge in early summer and feed on pine tree shoots, Van Hoosier said. When the nematode gets introduced to a susceptible tree, it denies nutrients and water to the tree, causing the tree to wilt and turn brown within a matter of weeks.

Once a vulnerable tree is host to the disease, it cannot be saved, Van Hoosier said.

“If you have an infected tree, you have to get it cut down and either mulched or burned or buried,” Van Hoosier said. There are preventative measures that can be taken to ward off the disease, however.

And the first and easiest way to protect trees is by ensuring they are healthy, Van Hoosier said.

“These beetles are kind of like wolves — they pick off the weak trees first,” Van Hoosier said. “So if your tree is stressed, it doesn’t have the right water, it doesn’t have good soil, it doesn’t have a mulch ring around it, that tree is more susceptible to being hit.”

The second protective measure is an insecticide injection that qualified arborists can administer annually. That injection can be costly and cause long-term damage to the trees, though, Van Hoosier warned.

With the summer ending, Van Hoosier said new cases may not be detected until next year, but the time to begin guarding against the disease is now. He encouraged anyone who believes they may have a vulnerable tree on their property to reach out to the city forestry program or another qualified local arborist.