The wisteria is one of those welcome fast growing vines that many gardens can benefit from. The small pea-like flowers hang in lovely clusters of purple, blue, pink and white and emit a lovely fragrance. Although the plant is generally resistant to diseases, the following may afflict your wisterias.
This is a bacterial infection that causes galls to develop on the plant roots and stems. As the infection increases, the plant health is affected and growth is retarded. The disease has no cure, although you can remove the galls and disinfect the wounded parts of the plant.
Mildew is caused by a fungal parasite. Initially, the mildew resembles powdered spots on the foliage but later develops into a grayish coating. As the infestation increases, the leaves wilt and finally drop off. Use a fungicide on the leaves and other affected plant areas. Be sure to remove and destroy all infected plant parts.
There are various leaf spotting diseases that are caused by fungi. They initially look like discolored spots on the surface of the leaves and consist of concentric circles. Heavily infested leaves will wilt and drop off, leaving the wisteria with little foliage. Make sure you pluck off and destroy all spotted leaves immediately when you notice them.