Branching Out
By Dave Meadows
Pioneer Columnist
It is important to understand that most tree pests and diseases are a secondary symptom of an underlying primary problem. Tree stress factors can contribute to many problems or complexes, rather than a single issue. Therefore, the professional diagnostic process can be challenging and involve proper tree identification, what abnormalities affect this tree type, site history, environmental stress, looking for patterns to the symptoms, and taking into consideration the client’s needs and expectations!
Diseases, in particular, can be difficult to diagnose and are often confused with other plant problems. In fact, if a primary stress factor is not readily identified, diseases are incorrectly assumed to be the existing problem. Pests are also easy to assume they are the primary problem, as we can see them causing damage to leaf tissues, bark and trunk flares, visible exit holes, webbing tents or structures on twigs or branches.
One fungal pathogen that is very prominent in the valley is Spruce Broom Rust (SBR). It is a common abnormality of Colorado Blue Spruce, Norway Spruce and Interior Douglas Firs. It is often associated with stem deformations, called Witches Brooms. Distinguishing features of SBR are complete loss of needles in the winter and the yellow-orange colour of the broom in spring and summer.
SBR Fruiting bodies and beginning of Withes broom deformity in the mid crown of spruce. Castlerock.
Orange fruiting bodies of Spruce Broom Rust (SBR) visible in early spring or summer.
Another tree pest abnormality in Invermere has been the White Pine Weevil (WPW). This beetle-like weevil has been a common problem in the Castlerock and Westside Park areas and has been mostly associated with spruce trees, predominantly Colorado Blue spruces. Adult female Weevils overwinter in garden mulch or forest litter, and, in early spring, they emerge and climb up the trunk of host trees up to the terminal shoot, deposit eggs in cavities in the bark. Eggs hatch within 10 days, and larvae burrow into the bark and feed on the inner bark. This results in the loss of the previous and current years’ terminal shoots. Presence of the insect is easily detected in late June by the condition of the terminal shoot or leader. i.e., wilted, orange shepherd’s crook. Control for both of these common evergreen tree problems can be solved by pruning out the obvious deformed growths created by each of these pathogens. As with SBR, it is recommended that you disinfect pruning tools after each cut of infected twigs or branches. I use household Lysol spray as it does not pit steel blades.
As for WPW, it is important to cut terminal shoots or leaders below the dead tip far enough down to new growth and look for larval tunnels, or pupal cells lined with sawdust, directly under the bark. If not cut far enough down the leader, next year’s adults will emerge and drop down to the mulch, overwinter, and begin another generation to continue deforming the host tree tops and other trees close by. Also, spruce tree trunks can be banded with sticky tape at the base to inhibit migration of adult weevils in fall.
The District of Invermere is taking proactive measures to prune out all WPW and SBR’s from publicly owned spruce, pine and fir trees. It is highly recommended that private homeowners recognize these signs of WPW (dead tops) and SBR (orange brooms) and prune out the affected growths as described or, call a Certified Arborist to perform the task or make recommendations.
Dave Meadows has been an ISA, Certified Arborist since 1996. Dave owned and operated Invermere Tree Care until his retirement this year. Dave also works part time for the District of Invermere, Public Works, helping with municipal tree care operations, and planting new trees for the Urban Forest.
