Rose leaves and blossoms dying

This problem concerns two David Austin roses, Graham Thomas and Mary Rose. They are about six feet apart. I have many other roses on my property but not close, none affected.
I am enclosing photos of the affected leaves. The plants have had enough water.
A few of the leaves are dying also flowers and buds wilting.
I have never used any sprays on these plants and I have only fertilised Graham Thomas once this year and Mary Rose, not at all, it being new this year.
I am in the Arrow Lakes area in British Columbia, Zone 5.
Thank you for your help.
Jennifer

 

Maybe physiological leaf burn of new growth due to hot weather. Or something that affects the roots, like honey fungus. You might want to look through this.

http://plant-disease.ippc.orst.edu/plant_index.aspx?title=disease

 

Thank you for responding and for the link. The closest I can find is, Powdery Mildew but not quite right. Yesterday there were about six blooms and buds flopping over on Mary Rose. Graham Thomas is out of bloom at moment. The former is the worst affected. I have, what I think is a ground squirrel hole about one foot from the M.R. and the run goes in the direction of other rose but this creature has been in my Secret Garden for a few years now and not damaged anything that I can see.
I shall investigate honey fungus.
Thanks again. Jennifer