THE ROLE OF FUNGI VECTORED BY<i>DENDROCTONUS BREVICOMIS</i>LECONTE (COLEOPTERA: SCOLYTIDAE) IN OCCLUSION OF PONDEROSA PINE XYLEM

Abstract

Abstract Following attack by Dendroctonus brevicomis LeConte, ponderosa pines were periodically sampled over 7 weeks. Xylem water conduction was assessed using a dye flow technique. Fungal isolations were made from functioning and occluded xylem. Neither Ophiostoma nigrocarpum (Davids.) de Hoog or other bluestain fungi were commonly found at the interface of the occluded and functioning xylem. Instead, blue-stain fungi appear to colonize already occluded xylem, not cause xylem occlusion by direct hyphal penetration of functioning sapwood. No evidence for a mutualistic association of D . brevicomis and its vectored bluestain fungi was found.