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.

Fungal Organism	B.C. Hosts	Identification
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	arbutus	Leaf spots, brown with purplish to reddish margins, 3-6 mm diameter form on living leaves (Fig. 62b).
Discula destructiva Redlin	dogwood	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.	willow	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	maple	Powdery white mycelium appears on leaf surface(s) in late summer and fall (Fig. 62j).

References:

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

Figures

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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.