Main trunk of Katsura tree appears dead-all the leaves are brown after coming out green, but two smaller trunks are still green.

Question

My Katsura tree, about 5 years old, has learves that turned brown almost overnight. There are two smaller branches or trunks that seem all right. Their leaves are still green. Should I cut off the portion of the tree, at the base of the main trunk, where the leaves have browned, or should I wait until next year? And should I start watering regularly? I haven’t needed to water for a few years, with no leaf dying until this year. And, this has been a particulrly wet year here in Wisconsin.

Answer 1

There appears to be a stem canker (from a fungal or water-mold infection) at the base if the primary stem. This is most likely a result of over-watering from the lawn surrounding the tree.
The infection may originate in the roots and root crown below the soil grade. Therefore cutting out the primary stem may not stop the infection from affecting the remaining stem. At this advanced stage of infection it is difficult to stop it. You may lose this tree.
Trees and grass have different water needs and the trees often cannot tolerate the frequent watering that lawn grass requires.