Guignardia Leaf Blotch
Karen Rane, Sr. Plant Disease Diagnostician,
Dept. of Botany & Plant Pathology, Purdue Univ.
The blighted areas on these horsechestnut leaves are symptoms of
fungal disease called Guignardia leaf blotch. The disease affects
species of horsechestnut and buckeye (Aesculus species).
develop as light green or yellow blotches or spots, which become
reddish-brown with yellow margins as the lesions mature. Blotches
most of the leaf surface, and affected leaves often drop prematurely.
fungus overwinters on fallen infected leaves, and spores from leaf
are splashed onto developing new foliage and cause initial leaf
spring. Spores are produced in leaf lesions throughout the summer,
While the symptoms are quite noticeable, the impact of this disease
health is minimal, since severe symptoms develop relatively late
growing season. Fungicide applications may be warranted in nurseries,
are not recommended for home landscapes.
For more information on this disease, see the following link: Guignardia
Leaf Blotch -
Click image to enlarge
Figure 1. Horsechestnut tree showing large areas of browning foliage
due to Guignardia leaf blotch.
Figure 2. Blighted horsechestnut leaves.
Figure 3. Close-up of horsechestnut leaf showing brown blotches
with yellow margins.