Beech Canker

Bleeding canker in Beech is caused by Phytophthora spp., a well-known genus of fungi capable of causing serious damage in many hosts. In the case of Beech it can cause root rot as well as trunk and branch cankers. Cankers form, coalesce and eventually weep a reddish fluid which stains the bark. As cankers girdle the trunk the crown thins, dies back, and can become chlorotic. Field diagnosis can be difficult and often requires lab analysis.

Treatment Strategy

Prevention of the disease is the surest control. Beech canker thrives in water-logged areas. It often begins in roots and moves upward into the tree’s trunk. Wounding of the bark creates avenues for infection. Reliant is the only fungicide known to mitigate this disease, though Mefenoxam may provide minimal control.

Other Treatment Practices

  • Preventing beech canker through cultural practices can save trees.
  • Air spading, mulching/RES, and proper watering can prevent infections from beginning. This can also help trees defend against the pathogen once they are infected.
  • Cambistat can help trees recover from stress. Along with the above cultural practices and Reliant, Cambistat can help trees regrow fine roots, increase leaf thickness, and increase tricome leaf hairs.
  • Mefenoxam has been shown to aid in control, but should not be used as a stand-along treatment.
  • Beech canker can also be associated with beech wooly aphid; application of Xytect can control this insect.

Bark Spray Using Reliant

Scrimmage With Reliant

Signs of Damage

  • Cankers and rot are the most common symptoms of this disease
  • Cankers can appear dark in color, sunken, weeping, or any combination thereof
  • Root rot is less-obvious to the casual observer, but exists both in overly wet and seemingly-normal conditions; this is often where infection begins in trees.

Bleeding cankers on the bark of a beech tree

Trees At Risk

  • Beech (Fagus spp.)


  • Phytophthora is a soil-inhabiting fungus-like organism that requires high moisture to complete its life cycle, and is most common under conditions of saturated soils.
  • The pathogen might initially invade small roots as well as crown tissue.
  • The pathogen is spread by movement of contaminated soil or diseased plants or by splashing water.
  • Even after host trees have died Phytophthora spp. are capable of surviving for months until conditions are appropriate for growth. Thus, many life stages are present in infected settings.
  • Multiple species of the pathogen often inhabit the same site.
  • On its own, phytophthora spp. spores can only move several centimeters while swimming with flagella. With flowing water as a vehicle though, the spores are capable of moving much larger distances.


Diseases of Trees and Shrubs, second edition
Wayne Sinclair and Howard Lyon
Copyright 2005 Cornell University


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