powdery mildew on rose tree

[Hallowitch]

Hi folks very little grows in the borders at the front of my house so I tend to concentrate on tubs growing flowers to sit on my decking at the back of the house anyway a few weeks ago I bought a couple of rose trees cheep from the supermarket turns out they have powdery mildew I cut of the affected bits and sprayed it with milk but that didn't work

On Sunday I sprayed them with Bayer Fungus Fighter but leafs still turning yellow and dying im thinking that one spray less than a week ago isn't going to solve the problem do I spray them every week or once every 2 weeks

bought deep tubs and used john innes no 2 to mix in with multi purpose compost and keep them well watered really hoping to save them or am I fighting a losing battle

Thanks Hallowitch

[Jeanied]

Some useful info on the RHS site - I was looking at it earlier this week as a few of mine have it too.

Rose powdery mildew/RHS Gardening