We have some Douglas Fir trees along a ravine. There is some construction nearby, and one of the trees is looking like it has been affected. It’s losing lower branches and has much less new growth than its neighbors that are farther away from the construction. Is there anything we can do to save it?
It certainly could be compaction, though it is not possible to diagnose from a distance. However, symptoms of soil compaction damage include drooping branches, wilted or scorched foliage, and conifers dropping inner needles. This came from the Minnesota DNR’s web site, which also discusses treatment. Here is an excerpt:
“Compaction can be partially alleviated by drilling a series of two inch diameter holes to a depth of 12 to 18 inches. Begin three feet from the trunk and continue drilling holes at two foot intervals in concentric rings around the tree and continue to at least the dripline. Each hole may be refilled with sand, peat moss or mulch. Don’t recap the hole with a sod plug. There are other alternatives, such as soil injections of air or pressurized water, available from some professional tree care services.”
A WSU extension formerly available online (“Construction Damage to Trees”) explains that careful watering and fertilizing can help damaged trees, though it is best to help them before damage is noticed.
Another good resource is the Colorado State University Extension’s “Protecting Trees during Construction.”
Finally it would be a good idea to consult the Plant Amnesty referral service at 206-783-9813, or search for an arborist at the PNW International Society for Arboriculture site under “Hire an Arborist.”