Cytospora Canker: This fungal disease targets the tree's trunk and branches by peppering it with brown, irregular shaped cankers. The ugly pimple-like masses can ooze and spread throughout the Mountain Ash. In a severe case, the disease can kill the tree.

What diseases do rowan trees get?

Unfortunately, the rowan tree can be prone to the Fireblight disease, as well as Silver Leaf Disease and the European Mountain Ash Ringspot-Associated Virus.

What is killing my mountain ash tree?

Emerald Ash Borer is a highly destructive invasive pest that arrived from Asia. In North America, EAB was first detected in Windsor, ON and Detroit, MI (2002) but was likely present in these areas for several years prior to its discovery. EAB beetles: metallic green in color.