Butt rot in mixed conifer stands. 70 years old Pseudotsuga menziesii trees on sandy soil, grown together with Pinus sylvestris, Picea abies, Fagus sylvatica were analysed for butt rot. 73 Yo resp. 70 % of the Douglas fir, 13 Yo resp. 28 % of the Scotch pine and 82 % resp. 84 % of the Norway spruce showed decay. The most frequent fungi in Pseudotsuga were Heterobasidion annosun, Calocera viscosa, Sparassis crispa, in Pinus Sparassis crispa and in Picea Heterobasidion annosum. In a neighbouring stand with 85 years old Pseudotsuga menziesii-more often thinned than the 70 years old stand -only 23 % of the trees were with decay.