• Decay fungi grow beneath the bark of trees, rotting them from within.Jupiterimages/Photos.com/Getty Images
  
  Magnolias are ornamental trees, well-known for their large, fragrant flowers and glossy foliage. Unfortunately, the magnolia has its share of pests. Several species of decay-causing fungi make a home in these trees, causing spongy or moist white rot and often sprout fruiting bodies. In fact, these fruiting bodies provide a means of identifying the fungus, which lives largely beneath the bark. These fungi damage the internal structure of the wood, weakening it until it becomes unable to hold itself up.
  
  

Ganoderma Applanatum and G. Lucidum

• Both Ganoderma applanatum and G. lucidum cause white rot in magnolia trees. They enter through wounds in the magnolia's bark and begin rotting the sapwood and heartwood. Ganoderma applanatum causes semi-circular conks --- which are the fungi's fruiting body and reproductive phase --- anywhere from 2 to 30 inches in diameter and 1 to 8 inches thick. Conks are brown on the bottom and white on top. Conks are found around ground level and signal the internal decay, which could spread as much as 15 feet from the site of the conk. G. lucidum prefers the roots of magnolias and other trees. It produces a conk as large as 14 inches with a dark orange, irregular surface. The damage is usually widespread by the time conks sprout, and trees are made more susceptible if they're stressed or damaged.
  
  

Pleurotus Ostreatus

• Pleurotus ostreatus decays sapwood, then heartwood and produces a white rot that is flaky in texture. It enters the magnolia through damaged areas and the larger the damage the more severe the decay. It produces clusters of shelf fungus mushrooms, each between 2 and 8 inches wide. A cluster of these mushrooms can be a symptom of either a local decay or heartwood rot stretching in 10 up or down the tree. These smooth mushrooms have gills on the undersides of their caps.
  
  

Schizophyllum Commune

• Schizophyllum commune also produces white rot in sapwood and an annual fruiting body. However, the fruiting bodies of S. commune are 1- to 4-inch, hairy conks that go from pale brown in youth to dark brown as they mature. They have tough skins and are usually found in clusters. S. commune prefers drought- or heat-stressed magnolia, or grow on trees that are sunburned, or which have major wounds. It prefers the dead sections of living trees.