When clematis wilt strikes, it takes just days for the foliage to shrivel and die. Wind spreads clematis wilt, a fungal disease affecting plants in sun and shade. Clematis x jackmannii and some of its big-flowered hybrid relatives are more prone to wilt than species clematis, which have better resistance. Although infected plants look dead, the disease typically affects the stems; the roots survive. New shoots may emerge from the ground. When wilt strikes, cut back the sick parts to healthy stems, even if you have to cut them below the soil. Apply a fungicide containing copper on any new growth that appears. Also, make sure you give clematis enough water to keep it from wilting from thirst.