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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Evergreen Trees and Shrubs > Arborvitae > Tree breaks or falls over

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Arborvitae > Whole tree > Tree breaks or falls over

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Armillaria root rot
Armillaria spp.

  • Infected trees have reduced growth, dead branches in the upper canopy, browning foliage
  • Flat white sheets of fungal growth (mycelial fans) between the bark and sapwood at the base of infected trees
  • Thick, black shoestring-like fungus can sometimes be seen under the bark at the root collar and in the soil near the base of the tree
  • The base of the tree just below the soil surface may be encrusted in resin
  • Wood is decayed, white, soft and spongy, beginning with the roots and may extend from the base of the tree well up into the trunk
  • Clusters of honey-colored mushrooms may grow at the base of the tree in fall
  • More information on Armillaria root rot...
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Brown root and butt rot
Phaeolus schweinitzii

  • Slow growth, thin canopy and discolored foliage in severely infected trees
  • Infection causes decay of heartwood in trunk and roots
  • Decaying wood has brown, cubical rot
  • Affected trees are often scattered, not adjacent
  • Infected trees frequently break or lodge in storms
  • 10"-12" fungal conks on trunk or several feet away from tree, velvety dark brown above and porous, light brown underneath
  • Most conifers are susceptible
  • More information on Brown root and butt rot...

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