Powdery and downy mildew on grapevines
If vine leaves are covered with a powdery coating on the top and beneath the leaves, this indicates an infestation with powdery mildew. The coating later turns brown and moves onto the grapes and shoots. The grapes burst open and dry out. Ask at your garden centre for a suitable product to tackle this.
Downy mildew on grape vines shows up on the top of the leaves in the form of so-called “oil spots”. Heavy infestations cause the leaves to fall at a later stage and the grapes to dry up (leather berries).