Current issue: 56(2)
The incidence of the conidiophores of Fomes annosus (Heterobasision annosum) was investigated in Helsinki in 1967–71 in a Norway spruce (Picea abies (L.) H. Karst.) stand growing on a site of Oxalis-Myrtillus type. The investigation comprised stump surfaces of spruce and pieces of wood, decayed by F. annosus, placed on the ground.
Conidiophores and conidia were seen during a few weeks in May-June on the surfaces of stumps covered by spruce branches. Conidiophores were sometimes seen on the stump surfaces even later in the summer and autumn, but by that time they were only very few. Their occurrence on the stumps that had not been covered was extremely rare, and the conidiophores were always very few in number. Surfaces of trees felled the year before showed no conidiophores. Conidiophores were also found below the pieces of decayed wood lying on the ground.
When spruce trees decayed by F. Annosus were felled in the summer and autumn, the surfaces of stumps covered with spruce branches showed the first conidiophores one week after the felling. The occurrence continued almost uninterruptedly until the winter.
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