Ganoderma Root and Butt Rot

Ganoderma applanatum

50 host plants

Last updated

Data Maturity Baseline

This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.

Gray-brown woody conks with white undersides appear at the base of Oregon white oak, indicating advanced internal decay. Ganoderma applanatum enters through wounds from pruning or equipment. Prevent by avoiding tree injuries during mowing and making proper pruning cuts. Large conks signal substantial decay; remove unstable trees to prevent property damage.

Avoid wounding trees to prevent decay. Mowing equipment should not injure the roots, crown, or lower trunk.

Quick Reference

Causal Agent
Ganoderma applanatum
Host Plants
50
Spread
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Favorable Conditions
Infected stumps and roots serve as inoculum sources year-round. Mycelial grow...

Management

Vulnerability Window

Root infection occurs year-round but is most active April–Oct when soil is warm and moist. Disease progression is very slow (years to decades). Visible symptoms and conk formation typically appear 3–10+ years after infection. Trees with advanced root decay may suddenly collapse. BBCH 10–89 for all stages.

What Triggers Infection

Infected stumps and roots serve as inoculum sources year-round. Mycelial growth and spread through soil/roots most active in warm, moist conditions (60–80°F). Root wounds and poor drainage increase susceptibility. Stress (drought, poor vigor, physical damage) increases disease expression.

Cultural Controls

  • Avoid wounding trees to prevent decay.
  • Mowing equipment should not injure the roots, crown, or lower trunk.
  • Make pruning cuts adjacent to, but not into, the supporting branch, and prune when branches are small to enhance callus formation and wound healing.
  • Inspect trees for decay and/or conks to assess tree stability Remove affected trees to avoid damage to surrounding property.
  • Reference Sinclair, W.A. and Lyon, H.H. 2005.
  • Diseases of trees and shrubs, 2nd ed.

Host Plants (50)

Quercus acutissima Sawtooth Oak Quercus agrifolia Coast Live Oak Quercus alba (Eastern) White Oak Quercus arizonica Arizona Oak, Arizona White Oak Quercus berberidifolia California Scrub Oak, Scrub Oak, Inland Scrub Oak Quercus bicolor Swamp White Oak Quercus bimundorum Two Worlds Oak, Bimundors Oak Quercus castaneifolia Chestnut-leaved Oak, Chestnutleaf Oak, Persian Oak Quercus cerris Turkey Oak Quercus chrysolepis Canyon Live Oak Quercus coccinea Scarlet Oak Quercus douglasii Blue Oak, California Blue Oak Quercus durata Leather Oak Quercus emoryi Emory Oak, Black Oak, Blackjack Oak Quercus engelmannii Engelmann Oak, Mesa Oak Quercus frainetto Hungarian Oak, Italian Oak Quercus gambelii Gambel Oak, Rocky Mountain White Oak Quercus garryana Oregon White Oak Quercus garryana var. breweri Brewer's Oak Quercus glandulifera Konara Oak Quercus glauca Japanese Blue Oak, Ring-cupped Oak Quercus hypoleucoides Silverleaf Oak, Whiteleaf Oak Quercus ilex Holly, Oak, Holm Oak Quercus ilicifolia Bear Oak Quercus imbricaria Shingle Oak Quercus kelloggii California Black Oak Quercus leana Lea's Oak Quercus lobata Valley Oak, Roble Oak, California White Oak Quercus macrocarpa Bur Oak, Mossycup Oak Quercus marilandica Blackjack Oak, Jack Oak Quercus mongolica Mongolian Oak Quercus montana Mountain Chestnut, Oak, Chestnut, Oak, Rock Chestnust Oak Quercus muehlenbergii Chinkapin Oak, Chinquapin Oak, Yellow Chestnut, Oak Quercus myrsinifolia Chinese Evergreen Oak, Bamboo-leaf Oak Quercus nigra Water Oak, Possum Oak Quercus palustris Pin Oak, Swamp Spanish Oak Quercus petraea Sessile Oak, Durmast Oak, Irish Oak Quercus phellos Willow, Oak Quercus prinoides Dwarf Chinquapin Oak, Dwarf Chestnut, Oak, Scrub Chestnut, Oak Quercus robur English Oak Quercus rubra Northern Red Oak Quercus sadleriana Sadler Oak, Deer Oak Quercus stellata Post Oak Quercus suber Cork Oak Quercus turbinella Scrub Live Oak Quercus undulata Wavyleaved Oak Quercus vaccinifolia Huckleberry, Oak Quercus velutina Black Oak Quercus virginiana Southern Live Oak, Live Oak Quercus wislizeni Interior Live Oak, Chapparal Oak