Receptivity of Picea sitchensis stumps to infection by Heterobasidion annosum basidiospores

Picea sitchensis stumps were inoculated with Heterobasidion annosum basidio spores either immediately or 24 h, 7 days or 28 days after cutting, in orde r to determine the length of time they remained susceptible to infection. C ontrol stumps were inoculated with sterile water; those that became coloniz ed were presumed to have been infected by natural inoculum. The degree of c olonization of inoculated stumps declined when spores were applied more tha n 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 da ta indicate that stump protection measures applied after felling must remai n 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.