An ash tree is a strong and handsome addition to a landscape, and correct ash tree pruning can promote the health of this specimen.
When you prune an ash tree is just as important as how you prune it. After all, pruning an ash tree incorrectly can introduce pests and diseases and subsequently weaken the tree. In the case of an ash tree, an ounce of prevention truly is worth a pound of cure.
How to Prune
The first pruning an ash tree should receive is at the time of planting. Examine the young tree to ensure that it has a center leader, or a strong central branch that will lead growth. Remove any branches of equal size that will compete with this central branch.
As the ash tree grows, prune to remove any dead, diseased or broken branches. These problematic branches can harbor fungi which produces decay, and which can affect other parts of the tree. Occasionally, pruning of live branches is mandated to allow sunlight and air to circulate within the tree’s canopy, since that can reduce the incidence of ash tree problems.
If you’ve inherited an ash tree, prune to remove any branch “stubs” which only serve to trigger weak growth in the ash.
Pruning is also a good idea to remove any branches growing back towards the tree’s center, any branches that grow at narrow angles, or any branches that are rubbing together. Be sure to make clean cuts, and don’t create stubs as you prune.
When to Prune
The Emerald Ash Borer is the nemesis of ash trees. This borer, a beetle that invades the bark of the tree, destroys the tree’s nutrient-carrying pathways. For this reason, avoid pruning an ash tree during June or July because the chances are then higher of being infested with ash borer.