Defoliation of <i>Tilia cordata</i> trees associated with <i>Apiognomonia errabunda</i> infection in Finland

Abstract

Highlights• Defoliation of Tilia cordata was investigated by fungal isolation from symptomatic leaf petioles and ITS sequence determination.• The disease symptoms were associated with the presence of Apiognomonia errabunda.• We report the first nucleotide sequences of A. errabunda from the Nordic countries. AbstractWe 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) Höhn. 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.

Change of Leaf Trait Asymmetry Type in Tilia cordata Mill. and Betula pendula Roth under Air Pollution

“…Perhaps, a significant asymmetry disrupted normal leaf functioning, and such leaves were eliminated by natural selection. It was reported that woody plants, including B. pendula and T. codata, lost some amount of leaves in summer [64][65][66][67].…”