Best time to cut down aspen trees with extensive oyster scale

Asked June 8, 2018, 6:05 PM EDT

We have two fairly mature aspens with extensive oyster scale and I would like to cut down before it can spread to other trees in our yard. When is the best time to cut down?

Eagle County Colorado

1 Response

Thank you for your question.

Firstly, is the tree covered in scales throughout the branches and the main trunk?
And to clarify, are you intending to cut down the entire tree?
Have you tried any pesticide strategies to manage the scale?

If you are planning on cutting down the infested Aspens (as a last resort for uncontrollable Oystershell Scale) I would recommend making a few observations on the tree itself prior to cutting it down.

I would recommend examining the areas around the scares carefully, to see if you can spot crawlers (the juvenile stage that can be seen searching for a new place to settle on the tree). If you see this stage actively crawling on branches, that is the ideal timing to treat this pest (and will help to minimize scale populations that could go on to infest other trees in your landscape).

Here is a Fact Sheet that goes into detail about controlling these scales.
You can use some of the recommendations to control scale populations prior to cutting down the trees.

Keep in mind, however, that "oystershell scale becomes much less vulnerable to most insecticides after the crawlers have settled, begun to feed, and molted to the next life stage during which the protective waxy cover begins to form. However, determining when the crawler period occurs does require some examination of the plants as timing can vary from season-to-season due to spring weather conditions. Crawlers are very small, but can be seen with careful examination of plants. Alternately they can be shaken off scale infested limbs onto a sheet of paper for easily view or can be trapped on double-sided sticky tape attached to infested limbs. Examinations to determine the onset of the crawler period should generally be begun around mid-May."

As for cutting down the entire tree, timing is not as important if you are planning on removing the tree entirely. Timing is a more important component when you are pruning, because you do not want to stress the trees. In the case of pruning, we generally recommend doing that in the dormant (winter) season. For your purposes, you can cut down the tree at any time that is convenient- making sure that the crawlers are not currently active.