Abstract
Stem cracks are damaging for timber quality and can reduce the monetary value of a tree both directly and indirectly: serving as gateway for fungal infections. Aim of the study was to assess the influence of tree dimensions and seed origin on the frequency of stem crack for Norway spruce. The study was carried out in two contiguous provenance trials (material from 12 countries), established in 1972 and 1975 in Western Latvia. Stem cracking was assessed using five-score scale. Most of the affected trees (90%) had very light or light damage. There was no relation of diameter at breast height to incidence of stem cracks. Analysis revealed a significant provenance effect on occurrence of stem cracks. Russian provenances tended to have lower risk of stem cracking and relatively narrow variation within the region, while Baltic and Ukrainian origins had wide range of stem cracking, having best as well as worst provenances in terms of cracking. Overall it is possible to select fast growing provenances with relatively low incidence of stem cracks.