Epsilon Archive for Student Projects

Abstract

Knäckesjuka (Melampsora pinitorqua) är en rostsvamp som orsakar skador på plantor och unga träd av tall (Pinus sylvestris) i Sverige, vilket lokalt kan innebära stora problem. Svampen har en komplicerad livscykel som innefattar en värdväxling mellan tall och asp (Populus sp.). Syftet med studien var att undersöka om sporer av knäckesjukasvampen är lika vanligt förekommande på hybridasp (Populus tremula x tremuloides) som på europeisk asp (Populus tremula). Med tanke på att hybridasp kan komma att bli ett alternativ som biomassaproducent är det viktigt att studera tänkbara risker detta trädslag kan föra med sig. Min hypotes var att hybridaspen är mer resistent än europeisk asp mot knäckesjuka, och att den därmed också sprider mindre mängd sporer som i sin tur kan infektera tall. Genom att inventera 12 hybridaspplanteringar etablerade åren 2005-2007 i Jämtland och Västernorrland och jämföra sporförekomsten på blad av hybridasp med blad på rotskott av europeisk asp på samma lokaler, samlades data in för att kunna testa denna hypotes. Signifikanta skillnader kunde ses mellan hybridaspen och den europeiska aspen på samtliga 12 lokaler. Totalt var endast 1 % av hybridaspens löv infekterade jämfört med 35 % av den europeiska aspens löv. Studien kompletterades med en inventering av tre hybridaspplanteringar etablerade i Västerbotten 1993, för att se om knäckesjuka förekommer även på äldre träd. Här var 3-6 % av hybridasplöven infekterade. Slutsatsen blev att knäckesjuka kan infektera även hybridasp, men att infektionsgraden är mycket låg i jämförelse med europeisk asp. Denna slutsats styrks av liknande resultat i tidigare studier. Eventuellt kan detta resultat öka motivationen för plantering av hybridasp. De skogsbrukare som tvekat inför hybridasp, på grund av smittorisken till närliggande tallföryngringar, kan med stöd av denna studie känna större tilltro till detta snabbväxande trädslag.

Abstract (eng)

Pine twisting rust (Melampsora pinitorqua) is a rust fungus that causes damage in plantations and young stands of Scots pine (Pinus sylvestris) in Sweden, which can cause extensive problem on a local scale. The fungus has a complicated life-cycle which involves two host species, Scots pine and European aspen (Populus tremula). The purpose of this study was to examine whether the pine twisting rust is as common on hybrid aspen (Populus tremula x tremuloides) as on European aspen. Considering that hybrid aspen likely will become an alternative for biomass production, it is important to know which risks it might bring. My hypothesis was that the hybrid aspen is more resistant to pine twisting rust than the European aspen, and therefore it will spread a less amount of spores that can infect pine. By measuring infection on 12 hybrid aspen plantations established in 2005-2007 in Jämtland and Västernorrland, and comparing the amount of uredospores on hybrid aspen leaves with leaves on suckers of European aspen at the same sites, data was collected to test the stated hypothesis. Significant differences were found between the hybrid aspen and the European aspen on all 12 sites. Only 1% of the leaves on the hybrid aspens were infected compared to 35% of the leaves on the European aspens. The study was complemented with an inventory of three hybrid aspen plantations established in Västerbotten in 1993, to conclude if spores of the rust were present on older trees as well. On these sites, 3-6% of the leaves were infected. The conclusion was that pine twisting rust can infect hybrid aspen, but the rate of disease incidence is very low compared to European aspen. This conclusion is also supported by similar results in earlier studies. Perhaps these results increase the possibilities for future planting of hybrid aspen. The forest owners that have hesitated to plant hybrid aspen, because of the risk of rust infection spreading to Scots pine regenerations, might with support of the present study have higher faith in this fast growing tree.

Pine twisting rust (Melampsora pinitorqua) is a rust fungus that causes damage in
plantations and young stands of Scots pine (Pinus sylvestris) in Sweden, which can
cause extensive problem on a local scale. The fungus has a complicated life-cycle
which involves two host species, Scots pine and European aspen (Populus
tremula). The purpose of this study was to examine whether the pine twisting rust is
as common on hybrid aspen (Populus tremula x tremuloides) as on European
aspen. Considering that hybrid aspen likely will become an alternative for biomass
production, it is important to know which risks it might bring. My hypothesis was
that the hybrid aspen is more resistant to pine twisting rust than the European
aspen, and therefore it will spread a less amount of spores that can infect pine. By
measuring infection on 12 hybrid aspen plantations established in 2005-2007 in
Jämtland and Västernorrland, and comparing the amount of uredospores on hybrid
aspen leaves with leaves on suckers of European aspen at the same sites, data was
collected to test the stated hypothesis. Significant differences were found between
the hybrid aspen and the European aspen on all 12 sites. Only 1% of the leaves on
the hybrid aspens were infected compared to 35% of the leaves on the European
aspens. The study was complemented with an inventory of three hybrid aspen
plantations established in Västerbotten in 1993, to conclude if spores of the rust
were present on older trees as well. On these sites, 3-6% of the leaves were
infected. The conclusion was that pine twisting rust can infect hybrid aspen, but the
rate of disease incidence is very low compared to European aspen. This conclusion
is also supported by similar results in earlier studies. Perhaps these results increase
the possibilities for future planting of hybrid aspen. The forest owners that have
hesitated to plant hybrid aspen, because of the risk of rust infection spreading to
Scots pine regenerations, might with support of the present study have higher faith
in this fast growing tree.