You're right Sutekesh, I chose to use the Latin name, for else I only could translate the Dutch "Valse Meeldauw"; to False Mildew", but it of-course is Downy Mildew!
Stems get purplish-blueish spots, that expand and the next year those canes/stems die.
The leafs get at the underside a grayish layer, the leaves rot or dry depending the weather and fall off!