European Hornbeam fungal infection

Three of my Hornbeams started showing signs of a fungal infection that made the leaves turn brown and twigs to die back last summer. One tree died. On the surviving ones the leaves came out ok this year but are now showing signs of it again. I've been spraying with systemic fungicide while the leaves have been coming out, but it doesn't seem to help. I also tried Bordeux mixture last year. The trees were collected 3 years ago and were healthy until they started having the problem. They're in a free draining substrate.

Please could you have a look at the below images and let me know if you have any ideas what it is and how it could be treated? I think the remaining trees may die this year if I don't find a cure.





https://goo.gl/WePbUX

I hope that some expert will respond to your subject.
But cannot you take some of the infected leaves to an agronomist and get advice/treatment in person?

Thanks, but where do I find an agronomist?

I would try daconil fungicide (if it's approved and available or another general fungicide first. (Daconil is a trade name and you can google the active ingredient which is something like Chloro....) It will not "cure" infected leaves but will may stop the spread of the fungus.

Here in the US we have "Cooperative Extension Services" associated with Universities that will help citizens and farmers free of charge with their gardening/farming activities. Do you have something similar in GB?

Can you send photos to RHS, Kew or similar to ask for diagnoses?

Are you thoroughly spraying the underside of the leaves also?
You might try adding a few drops of dish soap as a surfactant to break the surface tension on the leaves.

How are those trees doing, Peter?