Q.Hedging Pyracantha
We have a substantial hedge around our garden of Pyracantha. It is 14 feet high and has been great feature for privacy from last year we have noticed a section has started to die and concerned that it may spread to the rest of the hedge. As you can appreciate this has taken a considerable number of years to establish. Can you give any reasons as to the possible cause?
The only thing different in this area is that I have had horseradish growing and the roots would have mingled. Could this be the problem? I have since taken the horseradish out but may be too late. Your advice would be welcomed.

Certified GKH Gardening Expert
Here are 2 very good links.
It's possible your plant could have been affected by Pyracantha Scab.
If you see no signs of disease or insects, it's most likely a pruning issue.
Here are a couple of links with more information.
http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/pyracantha.html
https://www.gardeningknowhow.com/ornamental/shrubs/firethorn/care-of-firethorn-bush.htm
Please let us know if you have any other gardening questions and happy gardening!