Problems with Manchurian Ash Trees

Article excerpt

Every now and then a tree problem suddenly emerges that result in dozens of calls and e-mails. The tree in question is Mancana ash - a variety of Manchurian ash. I wrote about problems with this tree in July of 2009. Here is a new one. I recently discussed just problems with ash anthracnose disease in my June 2012 column. Anthracnose disease seems to reoccur every year. I have noticed that this year that some Mancana ashes are dying of a disease that kills twigs and branches in different parts of the tree.

On the dying twigs and branches of Mancana ashes, there appears to be an unusual development of the twigs that causes them to flatten out and become distinctly deformed as shown in the attached image. Usually when this happens the twigs and branches develop into pronounced bow like form. The twigs have a disease that is referred to as fasciation. The exact cause of fasciated twigs is not fully known. They may be caused by a viral disease, environmental stress, or a genetic growth malfunction, or by a combination of factors. The twigs continue to grow until they die from growth related stress such as drought or from severe anthracnose disease in the case of ash trees. In southern Manitoba drought conditions have prevailed throughout much of the summer this year and also during the summer of last year. The prevalence of anthracnose fungal disease in these ashes is likely making the problem even worse. …