Other Broadleaf Foliar Diseases

Several other fungal diseases affecting the foliage of broadleaf trees are common throughout B.C. In general these diseases cause little damage in natural forests, but localized epidemics can result in significant economic loss in stands of broadleaf trees under intensive management.





Ciborinia whetzelii (Seaver) Seaver

aspen, cottonwood

Sclerotia form dark "inkspots" on living leaves that drop out in late summer leaving "shotholes" (Fig. 62a).

Didymosporiu m arbuticola Zeller


Leaf spots, brown with purplish to reddish margins, 3-6 mm diameter form on living leaves (Fig. 62b).

Discula destructiva Redlin


Tan-coloured spots and necrotic blotches form on leaves (Fig. 62c). Infections often progress to shoots and stems

Marssonina populi (Lib.) Magnus
teliomorph = Drepanopeziz a populorum (Demaz.) Höhn.

aspen, cottonwood, hybrid poplars

Diffuse orange-brown spots, 2-5 mm diameter, coalesce into vein-limited blotches (Fig. 62d).

Linospora tetraspora G. E. Thompson

cottonwood, balsam poplar

Irregular blotches of brownish grey discoloured tissue along leaf veins. Scattered black stromata appear as black dots, 0.1 mm diameter (Fig. 62e).

Mycosphaerel la populicola G. E. Thompson
anamorph = Septoria populicola Peck

balsam and hybrid poplars, rarely aspen

Circular black leaf spots form on both sides of leaves (Fig. 62f).

Rhytisma punctatum (Pers.:Fr.) Fr.

bigleaf maple

Stromata appear as "tar spots" on roughly circular areas of chlorotic leaf tissue (Fig. 62g).

Rhytisma salicinum (Pers.:Fr.) Fr.


Black stromata with raised centers 2-5 mm diameter form on upper leaf surfaces (Fig. 62h).

Taphrina populi-salicis Mix

cottonwood, willow

Golden-yellow leaf spots (Fig. 62i).

Uncinula bicornis (Wallr.:Fr.) Lév


Powdery white mycelium appears on leaf surface(s) in late summer and fall (Fig. 62j).


Funk, A. 1985. Foliar fungi of western trees. Can. For. Serv., Inf. Rep. BC-X-265.


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Figure 62a: Sclerotia of Ciborinia whetzelii on aspen.



Figure 62b: Leaf spots on arbutus caused by Didymosporium arbuticola.




Figure 62c: Dogwood anthracnose caused by Discula destructiva.





Figure 62d: Leaf spot symptoms on hybrid poplar caused by Marssonina populi.



Figure 62e: Stromata of Linospora tetraspora on discoloured leaf tissue.






Figure 62f: Leaf spots on hybrid poplar caused by Mycosphaerella populicola.




Figure 62g: Stromata of Rhytisma punctatum on bigleaf maple.




Figure 62h: Stromata of Rhytisma salicinum on willow.





Figure 62i: Leaf spots caused by Taphrina populina (similar to Taphrina populi-salicis) on cottonwood.



Figure 62j: Uncinula bicornis on bigleaf maple.