Maple leaf spot

French disease name: Tache des feuilles de l'érable
Pathogen name: Phyllosticta minima (Berk. & M.A. Curtis) Underw. & Earle
Kingdom: Fungi
Phylum: Ascomycota
Class: Dothideomycetes
Order: Botryosphaeriales
Family: Phyllostictaceae
Partial list of synonyms:
- Phyllosticta acericola Cooke & Ellis
- Phyllosticta saccharina Ellis & G. Martin

Distribution

Eastern Canada

Damage, symptoms and biology

The fungus creates small brown spots on the leaves and, in severe infections, when most of the foliage is affected, the leaves may be shed prematurely. Growing leaves are infected in the spring and initially develop yellowish-green spots. The leaves eventually die and turn a brownish colour. Black fruiting bodies of the fungus develop in the infected spots around the end of autumn. The spores produced by these fruiting bodies over winter in the leaf litter and cause new infections the following spring.

Other information

As with many foliar fungal diseases, cool, wet spring weather greatly favours the spread of the disease. To protect ornamental trees, the leaves of affected trees should be carefully collected and destroyed by burning or composting.