I live in Nipigon (north of Thunder Bay) and my Ohio Buckeye has numerous canker-like scars on the twigs. I wanted to ask someone in Toronto as you might be more familiar with this species. I’m a retired Forest Technician and can’t find anything in my pathology books nor on the web. There are not any apparent fruiting bodies on the wounds and nothing seeping from them however small black ants are in and around the wounds. The “wounds” don’t appear to affect the vigor of the twigs past that point and it’s trying to heal over them but they weaken it and the branches often break. I realize it may be out of it’s range but the tree seems to be putting out new branches and leaves each year. The tree is in full sun in a silty/sandy/gravelly soil and puts out good growth each year. My Butternut is in the same site and is doing well up here too.
Could this be some kind of frost damage? It does get below -30° C in the winter. Any help would be appreciated. (I tried to add a (0.5 MB) photo but it wouldn’t upload it)
The natural range of the Ohio Buckeye ends considerably south of Nipigon. And the minimum winter temperature it tolerates is typically not below -29 degrees Celsius. Accordingly, it is very possible that your tree is suffering from stress: trees under stress are more susceptible to canker diseases. Your tree may also be under stress because of dry growing conditions (Ohio Buckeye typically grows on flood plains) or winter damage due to the more extreme temperatures it encounters.
Among many other stress agents which could result in cankers are nutritional imbalances, animal damage and pruning wounds.
Cankers are typically a caused by fungi invading the distressed tissue. While it is not possible to identify the particular canker causing disease from your description, as your tree seems to be otherwise thriving, you could take steps to promote its continued health. This includes watering, feeding, mulching and pruning in order to keep your tree as healthy as possible. Remove the twigs with canker to avoid infection and the spread of the disease. In my experience Buckeyes are prolific growers so pruning away any damaged branches and twigs should not substantially change your tree. Make sure when pruning follow good pruning practice – pruning only during dry weather, making your cuts with a sterile tool, and making those cuts at least 10 cm below the edge of a canker.