Calgary Arborist – News & Resources

Severe Tree Dieback in Calgary

The fundamental issue was the failure of the trees to “harden off” for the fall. This resulted in severe dieback and in some cases tree death.

Here at Adair Tree Care this year we are getting many calls about trees in distress. Some of the trees are on leafing out only on specific limbs while others have failed to push out any new leaves at all.

So What Happened?

It all started last fall when we were getting unseasonably warm temperatures throughout September without our usual early frosts. Normally the temperatures would begin to drop in September and this combined with the reduced day length triggers the seasonal change in trees where they start to prepare for winter. Instead we didn’t get any “hard” frosts until the second week in October when the temperature dropped to anywhere between -6′c to -16′c depending on exactly where in the city you are located.This caused many problems but the fundamental issue was the failure of the trees to “harden off” for the fall.

Hardening off is the process that a tree goes through to prepare for the winter. This includes movement off water throughout the tree, the dropping off leaves, along with other physiological processes. Missing this important step caused water to freeze in the above ground portions of the trees, rupturing cells inside the trees which resulted in the die back that is being seen.

Green Ash With Moderate Frost Damage

Green Ash With Moderate Frost Damage

The tree pictured above was damaged by the fall frost. This damage is not as severe as some we have seen. Some trees as old as 30 years failed to produce a single leaf or are pushing up suckers from the base which shows that even with ample energy, the damage to the tree canopies was so extensive that the energy cannot be pushed back up through the damaged cells and structures.

Now What?

No rash decisions about whether or not to remove the trees should be made yet. Many trees are still producing leaves and seem to be showing signs of life (not usual for the first two weeks of July). If you are really concerned about your tree, consider contacting an ISA Certified Arborist, or request a consultation with an Adair Tree Care Arborist here.

Nora Bryan has also posted about this subject, find her comments here

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