The efficacy of Chondrostereum purpureum in sprout control of birch during mechanized pre-commercial thinning

The efficacy of mechanized pre-commercial thinning (PCT) done by a lightweight mini-harvester Tehojätkä together with the Chondrostereum purpureum (Pers. ex Fr.) Pouzar fungal treatment (dilutions 1:100, 1:200, 1:400) and control (cutting only) was studied for three years. The efficacy of the fungal treatment was defined as capability to prevent sprouting of birch ( Betula pendula Roth. and B. pubescens Ehrh.). The fungal treatment resulted in higher stump mortality and lower number of sprouts but it did not have a clear effect on the maximum height of stump sprouts. However, mortalities obtained in this study (34.1%, 26.8%, and 25.6% for dilutions 1:100, 1:200, and 1:400, respectively) were notably lower compared to previous studies which indicate that the accuracy of the spreading mechanism was not satisfactory. We conclude that it is possible to decrease stump sprouting with the fully mechanized fungal treatment but putting this implementation into practice needs more testing to increase efficacy.