Ganoderma applanatum. Formerly Fomes applanatus, G. applantum primarily affects living and dead aspen, basswood, beech, birch, cherry, elm, maple, oak and poplar. Its common and easily recognized conk is semicircular or bracket-like, and has a woody texture (Fig. 88). A conk can live from 5 to 10 years. Each year it adds a new spore-producing layer over the previous one. The white surface of this layer and the new margin of growth visible on top of the conk contrast sharply with dark brown to gray older parts. When bruised or scratched, the white layer of the fungus immediately turns brown. Because of this, G. applanatum is known as the “artist’s conk.” Some conks may grow more than 3 feet (1 m) wide.

These conks dispense spores profusely from spring to fall. The spores are carried upward by air currents and sometimes form conspicuous brown deposits on or near the upper surfaces of the conks (Fig. 89). The relationship of tree wounds and infection by this fungus is well documented. By the time conks develop, the stem has extensive decay and is prone to break during a wind or ice storm.

Oxyporus populinus.O populinus, formerly Fomes connatus, isanother major decayer of red and sugar maples. It is found primarily on ash, aspen, basswood, beech, birch, and elm. Like other decay organisms, infection occurs through wounds deep enough to expose the wood. The resulting decay seldom extends more than 3 feet (1 m) above or below the conks (Fig. 90).The conks often occur in clusters within old wounds, in cracks (Fig. 91), or at the centers of Eutypella (Fig. 83) or Nectria cankers. The irregularly shaped conks are white, spongy, shelf-like, and rarely larger than 6 inches (15cm) in diameter. Typically, they have green moss growing on the upper surface (Figs. 83, 92).

Fomes fomentarius. Fruiting bodies of Fomes fomentarius known as the “tinder conk,” can be found on sugar maple, but they are more common on birches and beech. They are perennial, woody, hoof-shaped, about 4 inches (10cm) wide and relatively thick, and have a gray surface (Fig. 93). They are found on dead trees and on dead portions of living trees. Once the decay within a tree is extensive, the fungus produces conks on the stem in locations that bear no relationship to the presence of stem wounds.

Climacodon septentrionalis. A conspicuous conk occasionally seen on maple, C. septentrionalis (formerly Steccherinum septentrionale) is a large, fleshy, creamy white fruiting body composed of a cluster of shelf-like projections placed one above the other (Fig. 94). The entire structure may be as much as 1 foot (30am) wide and 25 to 30 inches (60 to 75 cm) long. The fungus infects through wounds and cracks and less commonly through dead breaches, causing a white spongy rot with characteristic black zone lines in the advanced decay. Decay in the tree is extensive by the time conks appear.

Laetiporus sulfureus. Another conspicuous fruiting body is produced by L. sulfurous (formerly Polyporus sulfureus). Clusters of shelf-like structures appear on infected trees in summer and early fall (Fig. 95). They are soft, fleshy, and bright sulfur-orange to salmon colored when fresh. Fruiting bodies can be 8 to 12 inches (20 to 30 cm) wide. This fungus causes one of the most important brown rots of maple, ash, beech, cherry, oak, and several other broad-leaved and coniferous trees. L. sulfureus decays roots, butts, and stems. It significantly reduces wood strength, rendering infected trees susceptible to breakage and windthrow. Infection sites for this fungus are not known.