Diagnosis
Diagnose: Rose Powdery Mildew
Use these observations to decide what to check next.
Powdery mildew when white-gray colonies spread across living rose surfaces
Inspect both surfaces of the young leaves, then follow the coating onto red shoots, sepals, and unopened buds.
Powdery mildew looks like irregular floury patches or a thin felted mat, and infected young tissue may curl, twist, or stay small as it expands.
Check whether the white material returns or spreads on living tissue after a gentle rub. Angular purple lesions with sparse growth underneath, dark spots with yellow halos, gray decay on petals, fixed water marks, or fine mite webbing all point somewhere else.