Fungal Pathogens

• Silver maple tree trunks are susceptible to wood decay fungal infections that produce fungus growth on the outer and inner bark. Decay of living silver maples due to fungal infections is also known as heart rot. Wood decay fungi break down living and dead tissue on silver maple trunks. Four common wood decay fungi infect silver maple trees: Ganoderma applanatum, Steccherinum septentrionale, Dadaelea unicolor and Oxyporus populinus. While some wood decay fungi is harmless on healthy silver maples, other pathogens can cause serious damage.
  
  

Identification/Symptoms

• The fungus, Ganoderma applanatum, produces larges conks on living and dead silver maples that measure about 20 inches wide. Ganoderma applanatum wood decay does not cause serious damage to healthy silver maples. Steccherinum septentrionale fungi produce light to brown, clustered conks on the bark trunk of silver maple. The most lethal wood decay fungi are Dadaelea unicolor. Shelflike conk growth on stems and branches and a light to gray coloring identify Dadaelea unicolor. Silver maples bark is the first line of defense against decay; however, the fungus decays bark and wood, which makes it lethal because it causes heart rot, or decay on the interior wood. Oxyporus populinus produces shelflike fungal growth on maple wounds and cankers. The fungus measures about 4.7 inches wide and has a pale yellow coloring. However, algae can grow on the fungus, which can turn the color of the growth to green. All wood decay fungal infections can produce a decline in vigor, twig and branch dieback and rotted wood.
  
  

Favorable Conditions

• Fungal growth on silver maple trunks are opportunistic parasites. They favor damage in bark, moisture on damaged wood, weak trees and unprotected wood. Healthy silver maples typically outgrow and produce natural defenses against most wood decay fungi. Trees infested with insect pests and other diseases that reduce tree vigor make it easier for the fungal pathogens to infect the tree.
  
  

Control/Management

• Scrape and destroy fungal growth on silver maple to prevent the fungus from spreading. However, prevention is the first line of defense against wood decay fungi. Maintain tree vigor with regular watering, watering during shortage of rainfall, fertilization in the fall or spring and pruning dead and diseased branches to prevent infection. In addition, avoid mechanical and pruning injuries to prevent infection. Mechanical injuries are damages to the silver maple from pruning and other man-made injury to the trees bark. Tree professionals can help control and identify wood decay fungi to minimize the damage.