New Bark Beetle Hits Rim Country


As if the devastation of ponderosa and piñon pines by Ips bark beetles isn't bad enough, the Rim country's ongoing drought is allowing new pests to move in.

Junipers and Emory oaks are now coming under siege, according to Chris Jones, University of Arizona extension agent assigned to Gila County. It wasn't hard for Jones to find examples of dead trees on a recent visit to Payson.


Chris Jones, University of Arizona extension agent, examines a dead alligator juniper on the Gila Community College - Payson campus. The juniper beetle, a cousin to the bark beetle, is infesting and killing ponderosa pines.

"It was a very warm winter, and we found something on (Emory oaks) called the wooly oak aphid," Jones said, pulling his truck alongside a dead tree on Mud Springs Road. "All of the Emory oaks are just covered with them, and we've lost the weaker ones."

Infested Emory oaks are not difficult to spot.

"They were all brown this winter, and Emory oaks don't turn brown. They're evergreens. A lot of them came back, but we lost some of them."

Junipers are getting a double dose of trouble. First the trees are weakened by spider mites too small to see with the naked eye, and then juniper bark beetles move in for the kill.

The first juniper Jones ran into during a stop at the Payson campus of Gila Community College was an alligator juniper that had already succumbed. As he examined the tree, he explained the sequence of events.

"The spider mites won't kill it, but make it less healthy and less able to fight against the bark beetle," Jones said. "Spider mites are so small you have to have a lens to see them. They just look like black dots."

The juniper bark beetle had already left its handiwork, furrows made on the surface of the wood immediately under the bark. Jones pointed to a spot on the tree where a piece of bark was missing.

"They do this stuff," he said. "This tree has been hit with the beetle. This branch is already dead. It girdled off this whole branch."

Scientists and forestry experts don't know nearly as much about the juniper bark beetle as they do its cousin, the Ips bark beetle that attacks the ponderosas and piñons.

"We have very little knowledge about this beetle," Jones said. "Junipers are not economically important enough to have the research (done on them) like something that affects timber. Our agent in Yavapai County did some research and found some books from the 1950s where they talked about outbreaks during the droughts. But we've only identified this beetle down to the genus. We don't know if it's one species for all of (the junipers) or a species for each."

So far most of the damage to junipers is occurring south of Payson.

"You see it particularly down towards Rye," he said. "You see all those dead junipers down there and through Roosevelt. It's a little bit drier in those lower elevations."

Fortunately, Jones doesn't think the juniper beetle will have anywhere near the impact that the Ips beetle is having with the pines.

"I don't think we'll lose that many junipers, and I'm not too worried about the piñons," he said. "It's that old ponderosa forest I'm concerned about."

So far, about 6 million ponderosa pines have been killed on 800,000 acres of private, state, tribal and federal land. More than 65,000 acres have been affected in the Tonto National Forest.

Samples of the spider mites that are attacking junipers have been sent to entymologists at the University of Arizona for testing, but local residents don't have to wait for the results to begin fighting back.

"What people can do about it right now is spray their trees with soap and water, add a little horticulture oil if they want," Jones said. "That will coat the spider mite with the soap and that lets the water go into their trachea and drowns them."

In the forest, where individual treatment of trees is impossible, the infestation just needs to run its course. Jones looks at the big picture.

"The forest is dynamic," he said. "It's going to change and it needs to. Those droughts we had in the '50s took a lot of piñons and junipers."

And while the drought could last another decade or even longer, Jones said, the forest will eventually come back.

"What I see with nature is that some of those trees are going to survive," Jones said. "We don't know why, but there will be something there that puts out a seed crop, whether it's genetics or exclusion, or the trees in a certain canyon don't get hit.

"Some of them are going to make it."

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