Stump treatment with the root rot antagonist phlebiopsis gigantea : - sensitivity of P. gigantea spores to high pressure stress; - reduced water consumption for stump treatment

Abstract: Stump treatment today requires large quantities of clean water mixed with the protective product Rotstop, to fully cover the stump surface. In order to reduce the water consumption without reducing the coverage of the stump surface, the pressure in the stump treatment device can be increased. Therefore, the Phlebiopsis gigantea (Fr.) Jül. suspension used as a biological control agent to prevent Heterobasidion annosum (Fr.) Bref. infection was pressure-tested. The pressurized suspensions were compared with the control suspensions and the survival was monitored by measuring oidia germination on agar medium. Pressures up to 150 bars (15 000 kPa) were tested and showed no negative effects on the survival of the P. gigantea spores. Three Phlebiopsis gigantea suspensions, with the same quantity of P. gigantea spores but with different water amounts (the recommended water amount 1 l/m2 stump surface, a reduced amount of 0.5 l/m2 and an even more reduced amount of 0.25 l/m2), were compared with each other. This was done to investigate if it is possible to reduce the water consumption for stump treatment and thereby reduce stump treatment costs. The experiment was conducted on stem pieces (billets) of Norway spruce (Picea abies (L.) Karst.) in a laboratory, and the amount of Heterobasidion infection was screened. Results showed no difference between using 1, 0.5 or 0.25 l/m2.