Need Help: Pruning a 30-year old Emperor 1 Japanese Maple in Decline

[VirginiaTrees]

We recently moved to a new house which has a 30-year old Emperor 1 Japanese Maple (16' x 15') which isn't doing well. Some of the tree shows no sign of growth while other portions of the tree has leaves in the form of suckers. Some of the suckers have grown 10-12" in just this season. There is some growth on the outermost branches in several places. Total coverage of growth on the tree is less than 10%. There are just two places where the old tree suffered from a late frost. We have another tree that propagated itself and is now about 8' tall. We are trying to figure out what to do about the existing Japanese Maple and are looking for guidance/recommendations.

Orientation and Environment: The JM is on the North side of the house, about 30-feet away. It receives direct sunlight between the hours of 9 and 130. Soil is well drained and from what we can tell, the feet aren't wet, but it has been getting good water throughout the growing season, naturally.

Please ignore the branch that died on the Leyland Cypress to the left. When I was inspecting the JM during the Winter, I pushed on the branch and it cracked in cold weather and haven't cut it out yet.

In the first picture, it shows the overall tree as it is today. I've made notations to add some context. Almost all leaves on the old JM are maroon in color. The new JM started out bright red and has gone bright green as the Summer progresses.

 

[Marck]

Greetings, welcome to the Forums.

'Suckers' is a term that is used very loosely when referring to branches that are perceived as undesirable. In the narrowest definition only branches from the rootstock of a grafted plant would be suckers. Others will also include any branches arising from the soil or base of any tree as a sucker. Still others seem to describe any rank growth or water-sprout as a sucker.

In my opinion your Emperor One Japanese Maple (Acer palmatum 'Wolff') does not have any suckers, it just has vigorous growth that is trying to reestablish the continuity of its canopy, after the major setback of having half of itself die.

If I understand your diagram arrows correctly, your tree has one or two main trunks that are dead and one main trunk that is alive. You should cut off the dead trunks just above soil level using a sloping cut to shed water. In Winter, you can also do some thinning of live branches on the remaining part of the tree but do so sparingly, unless you are trying to limit the canopy spread.

Classically, that green Japanese maple sapling is too close to the parent tree and would be removed. However this decision really depends on what look you are going for. If you want a denser thicket of trees with intermingling green and red-leaved branches then let the sapling stay, but if you want the Emperor One to stand alone as a symmetrical specimen then take out the sapling.