White powder on new rose leaves

Geoffrey Porter asked 9 years ago
My rose bush’s new leaves have what looks like a white powder on them. See attached picture. Can you please advise what this is and how I might correct it?

1 Answers

Gerry Daly Staff answered 3 years ago
This is rose mildew disease, which disfigures and weakens the bush.

It looks like the rose is growing by a wall and the soil would be dry and this encourages mildew, as does too rich feeding and too much organic material.

Water the rose in a dry time and increase potash feeding to harden the growth.

It is likely that spraying with a rose fungicide such as Roseclear or Multirose will be needed. While this is not essential, considerable disfigurement of the foliage and reduced flowering will result without spraying.