At my cottage, there is a mature cedar tree standing on the shoreline. My father built the original cottage in 1961, and from old photos, I can guess that this tree was just starting to grow back then. Today it must be more than 50 feet tall. Over the past few years, the top branches have lost their foliage. It appears that these branches are dead with some moss growing on them. Is this a sign that the tree is at the end of its life? Is there anything I can do to prevent or slow this process down, for example, provide nutrients to the tree to better its health?—Eric Hintermueller, Lake Labelle, Que.
A 60-year-old cedar isn’t old, so it shouldn’t be at the end of its natural life. “Cedars can live to 200 years,” says Sylvia Greifenhagen, a research forester with the Ministry of Northern Development, Mines, Natural Resources and Forestry. “Some, even longer.”
So something’s obviously wrong, and “if there’s moss growing on the dead material, that suggests that it has been dead for some time.” That said, pruning away the dead parts of the tree could help, says Greifenhagen. “It may stimulate more buds to form on the living branchlets and produce more new foliage.” Of course, 50 feet is tall. “Pruning might not be feasible,” Greifenhagen admits.
Knowing what has caused the dieback would help you figure out how to rehab the tree. But that’s impossible to diagnose without close inspection of the tree. It could be a problem with the roots or the soil. It could be a disease. It could be a pest, which would leave cankers, exit holes, or webbing one could see “if one feels like taking out a magnifying glass,” says Leilak Anderson, an arborist in Wakefield, Que. Or it could be the weather, something as simple as a hot, dry summer. Often with trees, it’s a combination of factors that lead to demise. “A tree can become weak from a stressful environment of foot traffic and soil compaction, and then be attacked by pests, causing a quick decline,” says Anderson.
None of this information is actually helping you save your tree. You probably need an expert to investigate in person. Anderson suggests looking for an arborist near you, in your case, through the Société internationale d’arboriculture Québec. Meanwhile, try helping your cedar in the same way that you’d help any stressed tree. Give it water during times of drought—long, deep, once-a-week soaks to mimic rainfall. “Use a hose with low water pressure near the base of the tree and move it around within an hour’s time,” says Anderson. And mulch: do a layer two to four inches deep, fanned out so it’s covering the tree’s roots, not mounded around the trunk.
Got a question for Cottage Q&A? Send it to firstname.lastname@example.org.