Koelreuteria is subject to few diseases. A canker causes dead and sunken areas on the bark. Coral pink fruiting bodies develop on the diseased bark. Prune out infected branches and fertilize to maintain tree health.
Verticillium wilt may attack koelreuteria. The disease causes wilting and death of leaves on infected branches. Eventually the entire tree may be killed. Fertilize with high nitrogen fertilizer to stimulate growth.