The role of stump treatment as a preventive control method against Heterobasidion root rot in forestry

Heterobasidion root rot is the primary pathogen threatening forest health and causing significant economic losses in temperate and boreal coniferous forests. Once established, there is no fully effective method to eradicate the infection. However, applying stump treatment during harvesting can prevent new spore infections in healthy stands, as newly created stumps serve as ideal entry points for primary infections. Additionally, climate change is altering the period during which spores are produced, thereby affecting the timing and necessity of stump treatment. Three main substances currently available for stump treatments are urea, borates, and living saprophytic fungi Phlebiopsis gigantea (Fr.) Jülich. Although the use of urea and borates is restricted in many countries, we argue they remain essential piece in the toolkit for enhanced forest health, especially as rising temperatures associated with climate change may reduce the efficacy of living organisms like P. gigantea. This mini-review summarizes and critically evaluates the different stump treatment methods used against Heterobasidion species, with a particular focus on their application in the boreal region.