By Bripat
United Kingdom 
We have a Red berried Catoniasta growing up the face of
the front of our house. Sections of it have started dying off. What could be the cause?
17 Nov, 2014
Answers
I would imagine it's fireblight which attacks cotoneaster, pyracantha, and members of the Rosaceae family. You could try cutting out the infected parts for the time being but I think it's 'close of play' for your Cotoneaster.
17 Nov, 2014
https://www.rhs.org.uk/advice/profile?pid=160 gives info on fireblight
17 Nov, 2014
Photographs would be very useful, especially if you don't know the variety of the Cotoneaster you've got.
17 Nov, 2014