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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Evergreen Trees and Shrubs > Pine > Fungi growing on trunk or base of tree

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Pine > Trunk/Branches > Fungi growing on trunk or base of tree

1 of 4
  • Armillaria root rot 1
  • Armillaria root rot 2
  • Armillaria root rot 3

Armillaria root rot
Armillaria spp.

  • Infected trees have reduced growth, discolored needles, thin canopies; produce large amount of cones and eventually die
  • 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
  • Base of tree 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
  • Trees frequently break or fall over in storms
  • Clusters of honey-colored mushrooms may grow at the base of the tree in fall
  • More information on Armillaria root rot
2 of 4
  • Tomentosus root rot 1
  • Tomentosus root rot 2
  • Tomentosus root rot 3

Tomentosus root rot
Onnia tomentosa

  • Infected trees have reduced growth, discolored needles, thin canopies; produce large amount of cones and eventually die
  • Heartwood of infected roots and trunks decays, initially turning reddish-brown
  • As infection continues white pocket rot develops; decayed wood has elongated pockets or pits and may appear honeycomb-like in cross section
  • Affected trees are often scattered, not adjacent
  • Infected trees frequently break or lodge during storms
  • Large mushrooms, velvety brown above and porous, buff-colored below occur at base of tree or above decaying roots some distance away
  • More information on Tomentosus root rot
3 of 4
  • Brown root and butt rot 1
  • Brown root and butt rot 2
  • Brown root and butt rot 3

Brown root and butt rot
Phaeolus schweinitzii

  • Slow growth, thin canopy and discolored needles 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 conk on trunk or several feet away from tree, velvety dark brown above and porous, light brown underneath
  • Most pines and conifers are susceptible
  • More information on Brown root and butt rot
4 of 4
  • Heterobasidion root disease and butt rot 1
  • Heterobasidion root disease and butt rot 2
  • Heterobasidion root disease and butt rot 3

Heterobasidion root disease and butt rot
Heterobasidion irregulare (previously known as H. annosum)

  • Slow growth, thin canopy, and discolored needles in severely infected trees
  • Resin soaked bark at base of tree
  • Sapwood of roots and butt discolored brown
  • Groups of infected trees commonly found in area where trees have been removed
  • Wood decays with a stringy white rot
  • Trees eventually die, windthrow common
  • Popcorn like white fungal structures that grow into leathery fungal conk, white to reddish brown above, cream colored with multiple pores below
  • Fungal conks common on cut stumps but often rare on infected trees
  • Infects most pines and other conifers
  • Not yet identified in Minnesota; if found, contact Arrest the Pest: 1-888-545-6684 or Arrest.the.Pest@state.mn.us
  • More information on Heterobasidion root disease and butt rot

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