Canker (fungus – Botryosphaeria dothidea): The most destructive disease of redbud. Cankers begin as small sunken areas and increase slowly in size. The bark in the center blackens and cracks along the edges. The canker girdles the stem and the leaves above wilt and die. Prune and burn branches with visible cankers.
Leaf Spot (fungus – Mycosphaerella ceridicola with a Cercospora imperfect stage): The leaf spots are brown, circular to angular, from one-eighth to one-fourth inch in diameter, often with a halo. Premature defoliation may occur. Apply a fungicide labeled for general use on trees and shrubs, at 10 day intervals when spots first appear and during prolonged periods of wet weather.
Cotton Root Rot (fungus – Phymatotrichum omnivorum): Redbud is rated as highly susceptible to the cotton root rot fungus.
Verticillium Wilt (fungus – Verticillium albo-atrum): (See section on Verticillium Wilt)