Staff photo by Philip Wright
HEALTHY or dying? The owner of this ponderosa pine in Cottonwood fears the tree has been infested by bark beetles. Some of the tree's needles have died and turned brown. But misinformation may be as costly as the damage caused by the bark beetle.
When the destruction was primarily within our national forests, the information we received seemed to be straightforward. Scientists and other experts gave a gloomy prognosis: Once a ponderosa is hit by the bark beetle, there isn't any way to save it. That was the less-than-optimistic reality. But it was, apparently, reality.
Then, the beetle started attacking trees in parks, such as the middle park in Jerome, and a few landowners received the bad news that their ponderosas were infested. The reality isn't so easy to accept when the trees involved stand beside our homes. Removing and replacing ponderosa pines can be expensive. Besides, we like these trees. We want to save them.
Consequently, some homeowners are willing to try almost anything to save their trees before cutting them down. It doesn't have to be a guaranteed fix. People are willing to try something as long as there is some reasonable expectation that the tree has a chance to survive. Some homeowners have paid for special injections and fertilizers. Almost everyone who has tried to save a beetle-infested ponderosa has resorted to intensive watering, and some have dutifully sprayed the trunks of their trees once or twice a day, as they have been advised.
Phil Young, master gardener and volunteer at the Yavapai County Cooperative Extension in Prescott, believes people are wasting their money by trying to save pines that have been infested by bark beetles. He also said he isn't surprised that the beetle is invading private land and city parks outside the forest. "They will travel a mile," he said.
Young said the bark beetle, which is native to Arizona, stays in the tree only two weeks and then moves on. "In two weeks (the tree) is dead," Young said. "The beetles girdle the trunk a couple of feet off the ground."
Once the beetles have girdled a ponderosa pine's trunk, the flow of nourishment is cut off, according to Young. No amount of water, no special fertilizers or injections will save the tree, Young said.
"Injections go to the leaves," Young said. "But the bark beetle doesn't go to the leaves." He said fertilizing a tree during drought is probably the worst thing you can do to it. The tree must have ample water to process the fertilizer.
Young said the only thing to do when a ponderosa pine is infested with bark beetles is to cut the tree down and make certain the trunk is removed from the property.
"They're not going to make it," he said. By removing the infested trees, other pines nearby may not be attacked. But even removal isn't a guarantee that other trees won't be infested, he said.
According to Young, small ponderosa pines aren't as vulnerable to the bark beetle as the bigger and older trees. He said people should take that into account when thinning trees on their property, something he strongly recommends. He said the trees should be about 15 to 20 feet apart.
To help prevent infestation of healthy trees, Young said that proper watering is the only thing people can do. He said that watering next to the tree's trunk is not the right way.
"Water out at the drip line (end of branches)," he said. "Water from there outward, not back toward the tree." He said the growth pattern of the ponderosa pine's shallow root system is what dictates the proper watering method.
Water must reach fairly deep to do the trees any good, Young said. Using a sprinkler in a grass yard probably won't allow water to reach even shallow roots. "If you've got grass, the tree won't get any water," he said. Young recommends using drip hoses that are designed for watering trees. Those systems can be laid out around the tree's drip line and left running until sufficient water reaches the roots.
Young said that dead needles in a ponderosa pine do not necessarily mean the tree is dying from bark beetles. "It's brown needles in the top of the tree," he said. That situation does in fact indicate that a tree has been infested. But dying needles elsewhere in the tree, according to Young, is a natural pruning that occurs and is caused by sunlight being blocked to lower branches.
Young said that reports of other species of trees, such as cypress and juniper, dying from insect infestation are probably true. But he said it not the bark beetle. He also said those species of trees are not suffering damage to the same extent as the ponderosa pine.
The most important thing that can be done to help ensure healthy trees is proper watering, for all species of trees. "You can lose any tree if you don't water it," Young said.