Bark beetle population explodes in New Mexico threatening pinon trees with deadly blue-stain fungus, forestry experts hope late-season rain, cold winter, will limit spring outbreaks

Wendy Lisney

SANTA FE, New Mexico , September 22, 2013 (Associated Press) – Bark beetles' resurgence threatens NM pinon trees as summer ends

They're back — the same species of bark beetle that decimated New Mexico's pinon trees a decade ago.

Local arborists say populations of the match head-sized insect, also known as the ips or the engraver beetle, began increasing alarmingly at the summer's end.

"Fortunately, their populations didn't explode until right at the very end of this season," said Rich Atkinson of Southwest Trees and Landscape. "If they had gotten going in the beginning, we'd be in greater trouble. Now, at least, folks can have warning and do something about it before (the beetles) emerge in the spring."

Robert Coates of Coates Tree Service said the main difference from the beetle infestation a decade ago is that the current one comes as the Santa Fe area finally is getting lots of rain.

"We're hoping and praying that this summer rain continues and we have a lot of snow this winter, and this thing doesn't break out like it did before," he said. "So far, basically, what we're finding is clumps of a half dozen (infested) trees here and there.

"It's definitely much more than normal and, as a matter of fact, we've been taking out pinons every week. The problem we're having is that some of the landscape companies we work with, and others, are starting to kind of panic (landowners) around town. So we're just being inundated by panicked people, and there's not a whole lot that can be done."

Atkinson, Coates and other local tree experts say irrigating or applying insecticide can deter the beetles from infesting drought-stressed pinons, but once they have infected a tree with the blue-stain fungus they carry, the tree usually dies. The fungus retards the flow of moisture under the bark from the roots to the upper regions of the trees.

"The fungus basically shuts down all the flow and corrupts the transmission of fluids," Atkinson said. "Once the beetles are in, the tree is dead — end game. The only thing you can do for your trees is basically try to prevent their chewing into the tree. And the only way to do that is to hydrate it to the point where its sap flow will spit the insect right back out — that's the natural defense — or coat it with chemicals that are detestable to the insects and they go somewhere else."

"You can kill them all day long, but you can't kill the fungus," Coates said. "Watering is the main thing that's going to have a positive long-term effect."

Swelling numbers of bark beetles have been observed in Salva Tierra, Las Campanas, Eldorado, Arroyo Hondo and the Santa Fe foothills. But David Lawrence, manager of the forestry program of the Santa Fe National Forest, said he hasn't seen much increase in pinon ips beetles in the national forest so far, although he's observed a lot of dying juniper trees. Coates also reported that locust borers are killing Santa Fe's black locust and other Robinia trees.

Robert Wood, integrated pest management manager for the city Parks Division, said he's yet to see an upsurge in bark beetle populations in the urbanized pinons, but he has seen an increase in pinon needle scale — another insect that attacks drought-stressed trees and is a precursor to the bark beetle.

However, Wood said, among the nonurbanized pinons — outside the city, near trailheads and along the trails — bark beetle populations are increasing sharply.

There are more than 200 types of bark beetles. They are always present, but their numbers increase sharply during extended droughts. Millions of acres of pines in the Rocky Mountains, especially in Colorado and Wyoming, have been destroyed by an infestation that was identified in 1996, according to the U.S. Forest Service.

In 2002, bark beetles turned to New Mexico's pinon, the state tree. By 2003, some were predicting the state would lose 80 to 85 percent of its pinons. By 2004, large swaths of pinon forests — for example, along Interstate 25 between Santa Fe and Eldorado — were dead. By 2005, the infestation began to subside. Bark beetle populations were back to normal by 2006.