North temperate coniferous forests are known to suffer from root and butt rot caused by Heterobasidion spp., resulting in severe economic losses. Since the mid-twentieth century, various intensities of fungus-inflicted damage have been reported in Scots pine and Norway spruce stands first in the former Yugoslavia and later on in Serbia. Despite the observed damage, the measures taken to protect tree stumps, which serve as an entry for basidiospore infections, have been rare or absent. Sodium borate (borax) has been used at certain locations to prevent Heterobasidion infection following damage caused by wind or snowstorms. This study aimed to compare the efficiency of sodium borate and Phlebiopsis gigantea to control the establishment of new Heterobasidion infections and to assess the cost of stump protection using these protective agents. Two sites were chosen and both products were applied to the freshly cut stumps. Thirty stumps per treatment and 15 control stumps were analysed at both the sites after 3, 9 and 12 months; therefore, a total of 450 stumps were included in the analysis. The percentages of infection in the borax- and P. gigantea-treated stumps and the untreated stumps were 4, 7 and 20%, respectively. The efficiency of these treatments was very high and ranged from 78% (for borax) to 94% (for P. gigantea). The stump area occupied by P. gigantea ranged from 20–91%, and mycelia could be observed up to 50 cm inside the stumps after 12 months of treatment. The estimated costs of these treatments 5–5.7 Euro cents per stump, depending on the price of the product applied. Thus, the results of this research reveal that stump protection is both ecologically and economically justified.

Keywords: Picea abies, Heterobasidion spp., Phlebiopsis gigantea, chemical control, stump treatment, economic appraisal