Disease of Aspen (populus tremula)

[Northumberland Wildlife Trust]

A population of Aspen (Populus tremula) on one of our nature reserves has rapidly succumbed to disease this year and I am struggling to identify the cause. I submitted a report via tree alert earlier in the year, but I didn’t receive a response as I suppose the team are snowed under with reports of ash dieback and other economically important diseases.

The Aspen have cankers on the small branches and twigs. Searching through the internet, the closest match I can find for the disease is Black Canker (Ceratocystis fimbriata). However, I cannot find any reports of the disease in the UK and I wonder if anyone could suggest a more likely cause?

Thanks in advance for any help you can offer!