Receptivity of Picea sitchensis stumps to infection by Heterobasidion annosum basidiospores

Picea sitchensis stumps were inoculated with Heterobasidion annosum basidiospores either immediately or 24 h, 7 days or 28 days after cutting, in order to determine the length of time they remained susceptible to infection. Control stumps were inoculated with sterile water; those that became colonized were presumed to have been infected by natural inoculum. The degree of colonization of inoculated stumps declined when spores were applied more than 24 h after cutting but was still greater than in the control stumps at 7 days. Spores applied at 28 days did not result in stump infection. These data indicate that stump protection measures applied after felling must remain effective for at least 7 days, and that if stump treatment is not applied immediately after cutting, it could still have some protective value up to 7 days later.