This happened last year as well. I have four ornamental grapes growing along a north facing pergola which have always been beautiful. I pruned them right back a couple of years ago to paint the pergola. At the beginning of spring they grew really well and were very lush. One seems far more affected than the others although the others are also now showing signs of the same ailment. I live in Gippsland Victoria and we have had a very humid and wet spring/summer.
15 January 2012 11:11 AM
Sometimes if there is a spell of cold weather the grape leaves can change colour and prematurely turn red. Have you had some unusually cold weather this Spring/Summer? You could also check the back of the leaves to ensure that there are no mites present as these can cause the leaves to turn bronze or brown in colour. Sometimes slight webbing can be also be seen on the back of the leaves. If you suspect that mites are present use some Yates Nature's Way Vegie & Herb Spray Concentrate.