Healthy Trees

The following information is provided to help owners prevent loss of trees and maintain a healthy forest. The DPHOA Board or the resident manager may contact property owners regarding dead or diseased trees located on their lot.

One of the things that enhance our quality of life in Duquette Pines is the beauty of the ponderosa pine trees that surround us. Although dead and dying trees are always part of the natural environment surrounding our homes, it is still painful to see a favorite large, old ponderosa pine tree or a grove of young pines, turn from a healthy green to foliage of rusty orange.

Most people living in the subdivision either have or will experience the loss of one or more of their pine trees sooner or later, but there are some things we can do as homeowners to keep our pine trees as healthy as possible and reduce the risk of death touching them.

Ponderosa pine is a long-lived hardy tree that survives well in droughty climates and on harsh nutrient deficient soils. In short they are pretty tough. Most of the larger pines in Duquette are approximately 100 years old, with a few incidental individuals older than that. These trees have reached an age where they are beginning to fully mature (how would you like to reach young adulthood at 100 years?), but they are also becoming more vulnerable to one of nature's "thinning agents," the bark beetle.

These little noticed insects (seldom larger than pencil lead thickness and less than 1/4 inch long) are the major killing agent of ponderosa pine in this area. While the threat of tree-killing bark beetles is always present, people sometimes unwittingly aid the bark beetle's cause, or neglect to remedy a situation that allows them to do their damage unhindered.

Three major species of bark beetles that prey on ponderosa pine live in our area. Each has its own ecological niche and attack the pines in different ways, but often work together. They are the turpentine beetle, western pine beetle and the pine engraver beetle (also know as Ips beetles). All three species of beetles tend to attack weakened or injured trees.

The turpentine beetle attacks the base of large trees, whereas the western pine beetle attacks the middle stem portion, and the pine engraver attacks the top. These beetles kill the trees, or portions of them, by boring through the bark during the warm late spring and summer months laying eggs as they go. The eggs hatch into soft bodied little white grubs, born very hungry, that further borrow and eat most of the tree's inner bark. As if this isn't enough, the adult beetles that attacked the tree in the first place bring with them a bluestain fungi that plugs the tree's water conducting system.

Have you seen what looked like a perfectly good looking pine tree look a little dry and off color one day, then turn a straw yellow color, and then a rusty orange color in what seemed like only a couple of weeks? The beetles with their fungi friend essentially girdle the tree inside the bark and quickly shut off the supply of water to the top. The young grubs mature and emerge from the dead trees that same year or the next, looking for new live trees to overcome. Sometimes the beetles can develop tremendous numbers moving from tree to tree in successive years, killing larger and larger groups of trees.

These are native insects doing what they were designed to do. But what can you do to prevent them getting the upper hand? As spring approaches and the snow is about gone, it is important to remove snow and winter damaged trees and slash, even if only 2 or 3 inches in diameter. These damaged and broken trees and limbs are highly attractive to the pine engraver beetles that quickly colonize the still green wood as the warmer days of spring progress. They produce several generations through the warm spring/summer months. When the second and larger generation emerges from the slash or damaged trees in late spring or early summer, they often attack neighboring sapling and pole size pines, or the tops of large pines, either killing them or severely weakening them.

Now enter bark beetle number two: the western pine beetle often comes in and finishes the job. The key here is to clean up any green slash and remove winter-damaged trees before these beetle populations can build up. For this same reason never bring green firewood home and stack it against or near live standing pine trees. Green firewood or slash that is bark beetle infested, or subject to being infested, needs to be either totally removed from the forested area, or burned. It can also be rendered useless to the breeding beetles by either removing the bark, or splitting the wood and drying it out in an open area with plenty of sunlight.

Covering the material completely with black plastic with no exposed gaps until the hot part of summer is another technique that can be used to kill any beetles already within the wood. The other key to your pines' health is simply to avoid doing things that injure or weaken them. Bark beetles are always in the forest. They are simply doing their job by removing the sickest and most weakened trees.

The best defense for your pines' health is prevention. Once the pines are successfully infested they cannot be saved. Please keep in mind the following suggestions to a avoid aiding the beetle's cause:

DO NOT stack green or infested wood next to live ponderosa pines.
DO NOT strangle pines with cables, clotheslines, wire, etc.
DO NOT smother roots of pine trees with earth piled around their trunks.
DO NOT cut off pine trees water supply with patios, concrete pads, etc. laid over their root systems.
DO NOT excavate or dig trenches near trees that sever major roots, or that suddenly changes the water table.
DO NOT be too eager to remove what appear to be "sickly" or off colored trees. They may be simply going through a normal needle shed.

DO clean up green slash and winter damaged trees.
DO keep ponderosa pines healthy and vigorous by keeping them well spaced out.
DO remove bark beetle infested trees.
DO contact a qualified forester or entomologist for help and advice on keeping your trees as healthy and long living as possible at either the U.S. Forest Service Ranger Station in Idaho City (392-6681) or Idaho Department of Lands in Boise (334-3488).

By: Ray Eklund

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