Several fungi cause leaf spots on carpinus. Leaf spots are not serious so control measures are usually not needed.
Canker caused by several fungi causes infected branches to dieback and entire trees die if the trunk is infected and girdled. Severely infected trees can not be saved and infected branches are pruned out.
Powdery mildew causes a white powdery growth on the leaves. The disease is not common on carpinus and can be controlled with sprays of benomyl used according to label directions.