Comments on the storm of 28-29 December 2010
This storm came into Truckee and Tahoe with a cold front. It then turned very wet and gradually piled up as the temperatures dropped. I have seen more broken tops in quaking aspen (Populis tremuloides) than ever before (several dozen while driving in town). There seems to be more damage at lower elevations, probably because it did not rain at the higher elevations so the snow was not as sticky. Aspen has a tendency to grow rather quickly when we water and feed it but it is usually fairly flexible. The trees that broke did not have unusually rapid growth, they were average, healthy trees. I am guessing that we will see lots of evidence of breakage in wild local aspen as well. We regularly see very disfigured and broken aspen in the canyons of the southern Sierra where we collect seeds of Villager Nursery's favorite, and indestructible, western river birch (Betula occidentalis var fontinalis).
I had been waiting to prune my broken Aspen until a little later. Any time after mid March should be fine (earlier and there will likely be drying and die-back from the cut). Cut just above, and sloping away from, the next substantial lateral branch, below the break, that can assume the role of leader. Do not cut to a small branch if there is any choice. By large I mean 1/2 - 2/3+ the diameter of the main trunk. As long as you are at it, go ahead and prune any competing leaders back to large laterals as well, it's called "subordination"of potential competitors. If pruned properly, the tree should "recapitulate" a new leader.
Aspen do best with one strong trunk and one stout and dominant leader. The narrow, pyramidal form that young deciduous trees and most coniferous evergreens exhibit is called "excurrent growth". I find pruning for excurrent growth is relatively simple to visualize and practice. Our first class of spring is usually, "Resurrection" after the ravages of winter.
Posted on Sat, January 1, 2011
by Eric Larusson filed under