Artificial inoculation with Ips typographus-associated blue stain fungi can kill healthy Norway spruce trees

Abstract

An infection experimcnt was made to test the pathogenicity of two Ceratocystis species on Norway spruce trees. Water stress in inoculated and control trees was measured by means of xylem water potential, stomatal aperture and transpiration stream velocity. Most trees inoculated with C. polonica, alone or in combination with C. penicillata, became water-stressed. Ten weeks after inoculation almost all sapwood of water-stressed trees was blue-stained at the level of inoculation. Trees inoculated with C. penicillata alone did not become water-stressed, and their sapwood was not blue-stained. The results indicate that C. polonica is a highly qualified accomplice to Ips typographus in its killing of spruce trees.