I have a hedge of about 80 hornbeam trees. They have significant number of inner branches that are dead, with black spots in them. The branches seem to be killed by the black fungus, starting at the tip of the branch, working its way towards the trunk. This is exactly what was shown in an earlier post from 2014 on your website, however, I don’t believe there was a definitive diagnosis. I have been told that a fungicide will not help the trees unless I have a specific diagnosis.
The diseased beaches look like those from this post. (I have the same issue as identified in the question posted on Jan 2014).
Was the cause and recommendation for treatment identified?
Thank you for your question. I have included the Jan 2014 post of my peers (that you referred to) as I think it is sound advice, see link below. The key points are:
1. Are you able to specify the type of Hornbeams that you are growing? This can help with the diagnosis of the disease and can affect the treatment type.
2. Even if you get a diagnosis for the specific fungus/pathogen that is causing the die back, you are unlikely to be able to treat the cause yourself, particularly if you are located in Toronto, by-law restrictions likely prevent you from treating with fungicide.
3. Given the large number of trees involved, a professional arborist assessment and treatment is recommended.
I would also add that the cause of your trees stress may be the issue, not just the fungal infection that has occurred as a result of inadequate growing conditions. If you seek the advice of a qualified arborist, they will be able to tell you as to whether your trees are planted at the correct depth and spacing, and if your growing conditions need amending, i.e. soil, light, moisture, nutrients.
Below, you will also find a link to the Landscape Ontario website, which should be able to help you find a licenced professional arborist in your particular neighbourhood.