Epsilon Archive for Student Projects

Abstract

Corinectria fuckeliana (previously Neonectria fuckeliana) has for a long time been known as a weak pathogen and endophyte invading wounds of Picea abies and other coniferous trees. It has recently been shown to be the causal agent of cankers on P. abies, leading to stem deformations and top- and branch-dieback. The long-term project presented in this thesis aims to answer how these cankers shape the stem quality and fungal community in the wood. This was started in 2011, when 60 trees of P. abies were inoculated with wood plugs colonized by C. fuckeliana. The length of the lesions that developed from the inoculation were measured in 2013, 2015, and 2025. The externally measurable length of the lesion was the largest in 2015 and has since appeared to shrink. From sampled wood cores of both inoculated and non-inoculated tissue within the same tree, the increment growth was measured in three-year periods from 2025 to three years before inoculation (2008). Increment growth relative to the three years before inoculation decreased significantly over time and the decrease was initially larger in the cores sampled from inoculated wood during the first six years after inoculation, and subsequently larger in non-inoculated wood during the period 2023 - 2025. The diameter of the inoculated trees and an equally numerous group of control trees was measured at breast height (where inoculations were made), 40 cm above breast height, and 40 cm below breast height. From this, the swelling was calculated as the deviation at breast height from the average between the above and below measurements. A median swelling of one cm could be observed in the inoculated trees, and a median swelling of 0 cm could be observed in the control trees. The fungal community within the wood was analysed by extracting DNA from inoculated and non-inoculated wood from the same tree. The ITS2 region was amplified and sequenced. The inoculation treatment was able to significantly explain about 2% of the variance in the fungal communities in the wood. Shannon-Weaver diversity index, and the relative abundance of C. fuckeliana did not significantly differ between the treatments. The relative abundance of fungal OTUs that were classified as resinicolous did significantly differ between the treatments.