Evergreen Clematis – Wilt
Q: I have a two-year old evergreen clematis that is climbing up over my garage. In the last couple of months it has started to turn brown at the ends of the vine and now all the leaves throughout are turning yellow. Another plant that gets the same amount of sun is doing great. Any ideas?
A: My experience with evergreen clematis (Clematis armandii) is the same as yours: sometimes parts of it die for no apparent reason. The good news is that mine has come back faithfully after each of these harrowing episodes.
Clematis gardeners have known of a disease called clematis wilt for decades. It seems that the larger-flowered varieties get the affliction more than the smaller-flowered types. One expert has theorized that extensive hybridization with a species clematis, Clematis lanuginosa, which came from China in 1851, led to disease susceptibility. Clematis montana, Clematis macropetala, Clematis alpina and Clematis viticella are reported to be wilt-resistant.
There is no fungicide registered for control of the disease. If your vine is healthy it will very likely come back again like mine does. If you plant one of the large-flowered clematis, install it deeply, with two or three inches of the lower vine covered in well-draining, loose soil. In this way if the top of the plant dies there will be healthy nodes belowground which will sprout anew.