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How to Manage Pests

Pests in Gardens and Landscapes

Pest identification and confirmation—Armillaria root rot

Mycelial fans between bark and wood
Mycelial fans between bark and wood

Armillaria forms characteristic white mycelial plaques between the bark and wood. These distinctive white fans have a mushroomlike odor and are visible when the bark is removed from infected roots and the lower trunk.

White patches
White patches of Dematophora root rot

Dematophora root rot also causes white growths that may be confused with Armillaria, but Dematophora tends to occur in smaller patches and grows throughout the wood rather than just under the bark.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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