I am in zone 5a and the location in question is partial shade with clay soils. I have 5 Carpinus betulus ‘frans fontaine’ that were planted three years ago. They are approximately 7′ tall, and in the spring I get a flush of growth then right around July I am seeing some of the terminal leaves and shoots brown and die back it is also followed by slight yellowing of the terminal leaves next in line. This happens on all 5 of the trees, however some worse than others. The soil is mulched and does not ever appear to be dried out.
Thank you for contacting Toronto Master Gardeners.
Carpinus betulus ‘frans fontaine’ or any of the Hornbeams do not have any significant diseases or pests. They are not susceptible to wilts or insect invasions. They are a sturdy trees that thrives in partial shade.
The cause maybe more of a local issue than something that affects the species.
- Has there been any changes to the environment? Has there been any digging, pool drainage or other construction in the vicinity of the trees?
- Has there been any issues with water pooling in the area not allowing good drainage? Any changes in irrigation?
- Has there been any chemicals put on nearby plants that maybe affecting the trees?
- Has there been any physical damage to the trees?
If there is no localized changes that could be affecting the trees, the next thing to look at is how were the trees planted?
- This problem can come from from being planted too deep. It often takes about three years to start affecting the tree. When you look at the base of the trees does the trunk start to flare near the ground? Trees should be planted no deeper than the root flare; the area at the bottom of the trunk where the roots branch off from the trunk. If the trunk is buried below this point the trunk begins to break down and the tree will eventually die.
- When the trees were planted were the roots loosened up and were there any roots wrapping around the trunk that may now be strangling the tree? If the trees were planted without removing wire baskets or burlap this may well be the case.
Calling a certified arborist to come and inspect the trees is a good way to diagnose the problem.
Good Luck, I hope you solve the mystery.