A Technical Report from The Bartlett Tree Research Laboratories
Leaf blotches are common on trees and shrubs and are caused by a range of fungi to include species of Glomerella, Discula, Diplocarpon, Gnomonia, and Guignardia. Leaf blotches can cause defoliation and may weaken trees and predispose them to other pests. However, it is very rare that these fungi cause twig or branch dieback. When branch dieback occurs, it is usually caused by root disease, girdling roots or a similar root disorder. Consequently, death rarely results from infection by leaf blotch fungi alone.