Armillaria root rot (Oak root fungus)—Armillaria mellea
Armillaria root rot, also known as oak root fungus disease or shoestring disease, affects many broadleaf
trees and conifers. Armillaria infects and kills cambial tissue, causing major roots and the trunk
near the ground to die. The first aboveground symptoms are undersized, discolored, and prematurely dropping
leaves. Branches begin dying, often first around the tops of trees or in the lower canopy of conifers.
Eventually the entire plant can be killed. Clusters of mushrooms may form at the base of trees. Black
or dark reddish brown rootlike structures (rhizomorphs) are frequently attached to the surface of roots
or the root crown.
Identification | Life
cycle
Solutions
Prepare the
site well before planting and provide proper
irrigation. Plant only resistant
species in locations where Armillaria root rot has been
a problem, such as where floods occur. Before replanting,
remove as many roots from the soil as possible because
these can harbor Armillaria.
Air dry the soil before replanting.
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Above
ground symptoms of oak root fungus
Mushrooms at base of infected tree
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