Wood Strength and Weight Losses Caused by Soft Rot Fungi Isolated from Treated Southern Pine Utility Poles


  • Jeffrey J. Morrell
  • Robert A. Zabel


Soft rot, tensile strength loss, weight loss, anatomical damage, utility poles, southern pine, American beech, <i>Phialophora</i>, <i>Phialocephala</i>, <i>Alternaria</i>, <i>Chaetomium</i>


Six soft rot fungi, commonly isolated from preservative-treated southern pine poles in service, were tested for their capacities to cause weight loss, anatomical damage, and tensile strength loss in southern pine and American beech. The fungi caused significant losses in both wood weight and strength in laboratory tests at two- and four-month periods. The weight losses were greater in beech than in pine and increased with incubation time, although not linearly. Weight losses caused by some fungi varied substantially with incubation temperatures.

Strength was reduced more rapidly in pine, and losses attained were up to 88% of the original wood tensile strength. Strength losses were lower in beech and appeared to be delayed. Reasons for this variation are presented, and the potential of soft rot fungi to affect the service life of treated wood products in ground contact considered.


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