Defoliation of Tilia cordata trees associated with Apiognomonia errabunda infection in Finland

We investigated the causative agent of a disease outbreak affecting small-leaved limes (Tilia cordata Mill.) and resulting in darkening of the leaf petioles and excessive defoliation during summer 2016 in southern Finland. The fungal species composition of the symptomatic petioles was examined by culture isolation and molecular identification using ITS rDNA sequences, which revealed the most prevalent fungal species present in the petioles as Apiognomonia errabunda (Roberge) Hhn. Based on reviewing curated herbarium specimens deposited at the Universities of Helsinki and Turku, A. errabunda is native and widely distributed in small-leaved limes in Finland, and occasionally infects also other broadleaved trees, including Quercus robur L. and ornamental species of Tilia L. and Fagus L. The ITS sequence analysis conducted during this study revealed minor within-species polymorphisms similar to those observed earlier in the Central European and Russian populations of A. errabunda, and reports the first nucleotide sequences of this species from the Nordic countries

Short-term impacts of energy wood harvesting on ectomycorrhizal fungal communities of Norway spruce saplings

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Interactions between soil- and dead wood-inhabiting fungal communities during the decay of Norway spruce logs

We investigated the interaction between fungal communities of soil and dead wood substrates. For this, we applied molecular species identification and stable isotope tracking to both soil and decaying wood in an unmanaged boreal Norway spruce-dominated stand. Altogether, we recorded 1990 operational taxonomic units, out of which more than 600 were shared by both substrates and 589 were found to exclusively inhabit wood. On average the soil was more species-rich than the decaying wood, but the species richness in dead wood increased monotonically along the decay gradient, reaching the same species richness and community composition as soil in the late stages. Decaying logs at all decay stages locally influenced the fungal communities from soil, some fungal species occurring in soil only under decaying wood. Stable isotope analyses suggest that mycorrhizal species colonising dead wood in the late decay stages actively transfer nitrogen and carbon between soil and host plants. Most importantly, Piloderma sphaerosporum and Tylospora sp. mycorrhizal species were highly abundant in decayed wood. Soil- and wood-inhabiting fungal communities interact at all decay phases of wood that has important implications in fungal community dynamics and thus nutrient transportation.201