Hello, I planted this japanese maple 3.5 years ago. In the last year it has started dying. We cut back the branches that were dying, last fall. The part that is dying is not sprouting new growth and the part that is surviving has a few dead branches on top, this spring.
The tree is in our westward facing front yard in downtown Toronto. It is very dry because there is also a very large Maple in the yard.
Can we save it? What is impacting it and what should we do?
Thank you so much for any help.
Sadly, I have seen this a few times before on Japanese Maples. While there could be many reasons for its slow demise including the competition for water from the large maple you mentioned above, from the way it is dying back I would highly suspect it could be verticilium wilt. Typically I have observed branches dying back one by one, often from the tips down. This is because this fungal disease affects the water conducting tissues of the plant and the tips are the furthest the water has to travel.
According to the Morton Arboretum:
“The fungus lives in soil as small, darkened structures called microsclerotia. These microsclerotia may lie dormant in the soil for years. When the roots of susceptible plants grow close to the microsclerotia, the fungus germinates and infects the roots of the plants through wounds or natural openings. The fungus spreads into the branches through the plant’s vascular system and simultaneously causes the plant cells to “plug” themselves. Once the xylem is infected, it becomes so plugged that water can no longer reach the leaves. Verticillium can also be spread to plants through wounds on branches or trunks.”
This is a tricky disease as it is soil borne where it can live indefinitely. If you are trimming back affected branches, make sure you sterilize your tools afterwards as it can be spread through your tools as well. If you opt to remove the tree, I would recommend choosing a replacement that is immune to this ailment. The Missouri Botanical Gardens provides a list here: https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/cankers/verticillium-wilt.aspx
I hope this is helpful in understanding what is affecting your tree.