This time of year seems to bring out the lumberjack in all of us, and as we look for woody shrubs that need a little trimming, we also inspect our trees for the stress damage of a long hot summer.
Heat and drought have taken a particularly heavy toll on native ponderosas. Beetles are infesting stress-weakened trees at astounding rates.
Cooler temperatures and increased humidity will slow the beetle's activity, and with a little luck, the home gardener can begin to defend undamaged trees against the next onslaught. Understanding the life cycle and habits of the insects that attack ponderosa pines will help to build defenses against them.
Shane Owens and his crew at Tree Pro in Payson spend their days helping to educate homeowners to take action against drought and insects, treating trees where feasible and removing infested trees if necessary, once the damage is done. Owens would much rather treat living trees and help residents keep them healthy than cut down dead and dying ones.
Owens explains that the ips beetle is a little black-brown beetle which bores through the bark of a ponderosa into the cambium layer of the tree and leaves a tell-tale sap-button on the surface, providing there is enough moisture for the tree to produce sap.
The sap button is a little ball of sap mixed with red dust from the ponderosa bark. If conditions are as dry as last summer, no sap emits from the bore hole, but red dust can be seen lying on the tops of bark sections.
A healthy tree can produce enough sap that, if attacked by just a few beetles at a time, will actually push the beetle out with the pressure of the sap, or drown it within the bark layers. Once inside, the beetle lays hundreds of eggs, which subsequently hatch, and the larvae begin to eat.
During drought conditions, the beetle reduces in size but increases in numbers and will attack a clump of trees, eat until the food source is exhausted and fly to the next available source.
They eat the cambium layer of the tree, interrupting the flow of water and nutrients, causing rapid death of the tree.
When temperatures drop, the beetle is unable to move, and if caught in a tree where the food source has been depleted, they will die. Because of our erratic winter temperature swings, sometimes beetles are able to be active during the winter, if even a day or two at a time.
The beetles also carry the spores of Blue Stain fungus, which fills the pores of the woody vascular system of the tree.
To keep trees healthy, remove or thin stands of tree seedlings from around the base and well beyond the drip-line of large trees. These smaller plants compete for water and nutrients.
Avoid planting a lawn around a ponderosa because of the chance of over watering, but native grasses, herbs, or wild flowers are fine.
If possible, leave needles around base of tree out to drip-line, or mulch the area with chipped pine mulch to add some acidity to the soil. During extreme drought, lay a soaker hose around the drip-line and slowly soak over a period of time to allow the deep penetration of water into the root zone. This treatment is only necessary every 4 to 6 weeks.
Cool temperatures slow the action of the beetle, but if you suspect you have an infestation, it's wise to call a professional. Trees can be injected or sprayed to reduce the infestation and sometimes partial pruning will remove infested wood.
What happens to all the trees that Tree Pro and others are removing? After inspection and treatment to make sure no beetles are present, most are being recycled as sawdust for pulp and pellets, logs for log homes, lumber for building, or firewood.
Owens explains that unless a tree has to be removed for safety or fire danger, leaving a large old snag is very beneficial to the environment. It provides perching and nesting for birds, a haven for insects, many of them beneficial, and as it decays adds necessary nutrients back into the soil.
For more information, call Owens at 474-0173 or log onto the Colorado State University website: www.colostate.edu/depts/CoopExt/TRA/PLANTS/ips.html.
Barbara Bourscheidt is a longtime resident of Payson, a member of the Rim Area Garden Club and a participant in the Gila County Master Gardener program. She serves on the board of directors of the High Country Xeriscape Council of Arizona, and she researches and writes articles on the subject of water conservation through creative landscaping and climate-appropriate gardening techniques.
A Bark Beetle Seminar will be held from 9 a.m. to 11 a.m. Saturday, Oct. 5 at the Pine Cultural Center. Sponsored by the Pine Fire Department and Gila County Cooperative Extension, homeowner recommendations and community action options will be discussed. For additional information and to reserve a seat, call the Pine Fire Department, 476-4272.