Epsilon Archive for Student Projects

Abstract

The effectiveness of Phlebiopsis gigantea to prevent spore infections from Heterobasidion
annosum and Heterobasidion parviporum on hybrid larch stumps were investigated in five
stands in southern Sweden. All sites are former forest land and the age of the trees was
between 9 and 13 years.
The study was implemented in August 2010, a month where spore dispersal should be great.
The five sites were located in previously un‐thinned monocultures of hybrid larch. The spore
load in the air was studied with the help of spore traps from three different tree species;
Norway spruce, Scots pine and hybrid larch. A total of 146 spore traps, evenly distributed in
all five sites were analyzed. The spore traps were exposed for three hours then brought back
to the laboratory for incubation and analysis. The hybrid larch trees were randomly selected,
cut down and every second stump was treated with Rotstop® S and the others were left as
controls. No visible signs of infections were discovered. Roughly 60 days after felling and
treatment, disc samples were collected for further analysis in lab.
The study indicates an abundant amount of basidiospores of Heterobasidion spp. in the air.
63,7 % of all spore traps was infected with Heterobasidion spp. Most infections were found
in Södra Rörum II, with 83 % infected spore traps. Out of 263 colonies, 61,2 % of the
isolations were infections of H. annosum and 38,8 % were H. parviporum. Scots pine and
hybrid larch were most attacked by H. annosum whilst Norway spruce was equally attacked
by H. annosum and H. parviporum. The mean percentage of infected stumps for all five sites
per tree species was; larch 52 %, Norway spruce 58 % and Scots pine 72 %.
A total of 176 hybrid larch stumps were analyzed and 20 % were infected by Heterobasidion
spp. Both H. annosum and H. parviporum were isolated from the hybrid larch stumps. 60 %
of the isolations were H. parviporum and 40 % were H. annosum. Highest infection rate was
found in Fulltofta and Klippan where 24 % of the stumps were infected.
There is a significant difference of infection rate and infected area between treated stumps
and un‐treated control stumps, where p < 0,000 and p < 0,024 respectively. This result
makes Rotstop® S an interesting stump treatment alternative also on hybrid larch.