Stump treatment against Heterobasidion with Phlebiopsis gigantea and some chemicals in Picea abies stands in the western Alps

The effectiveness against Heterobasidion natural airborne infections on Norway spruce stumps was tested for six treatments: aqueous suspension of Phelebiopsis gigantea oidiospores, 10%-, 20%-, and 30% aqueous urea solutions, 4% copper oxychloride aqueous solution, and borax powder. The experiment was carried out in four naturally regenerated forests in the western Alps, each characterized by a different airborne inoculum potential. Within each stand, all treatments, with the exception of urea 10%, were effective and resulted in colonized areas of stumps significantly lower than controls. The effect of ambient spore loads on the stump colonization is discussed.