Original scientific paper

First records of Chalara fraxinea in Croatia – a new agent of ash dieback (Fraxinus spp.)

Lea Barić ; Šumarski fakultet Sveučilišta u Zagrebu
Miljenko Županić ; Hrvatski šumarski institut Jastrebarsko
Milan Pernek orcid.org/0000-0001-8200-6913 ; Hrvatski šumarski institut Jastrebarsko
Danko Diminić orcid.org/0000-0001-5549-5870 ; Šumarski fakultet Sveučilišta u Zagrebu

Abstract

Chalara fraxinea is a novel disease responsible for common ash (F. excelsior) dieback during last 10 years in many European countries. The disease was also confirmed on narrow-leafed ash (F. angustifolia), and on American and Asian ash species.

The symptoms of dieback are especially visible in tree crowns, including wilting and premature leaf shedding, necrosis of bark and wood discoloration. Isolation of C. fraxinea from infected bark and wood on artificial media resulted in growth of morphologically specific colonies. The telemorph of C. fraxinea, Hymenoscyphus pseudoalbidus apothecia, are developed on leaf petioles from previous year in the litter. Ascospores of telemorph are wind-dispersed, and are responsible for the rapid spread of this disease.

Presence of C. fraxinea on common ash trees in Croatia was first recorded in Gorski Kotar region in 2009, affecting trees of different ages. In the same year, pathogen was successfully isolated from necrotic bark and wood tissues. In 2010 and 2011, research was expanded on larger territory of Croatia in order to determine distribution of the pathogen. The shoots and branches with developed symptoms were collected from common and narrow-leafed ash. In May 2011, four sample plots of common ash were marked in Gorski Kotar region. On each plot, 20 ash trees affected with C. fraxinea were selected for monitoring of health condition changes. The assessment of crown condition (foliage transparency) was made on selected trees on plots, also registering the other biotic (wood decay fungi, insects damage) and abiotic (frost, windthrow, snow damage) factors that could additionally have influence on ash dieback. Leaf rachises with mature H. pseudoalbidus apothecia were sampled from litter for further analyses.

The biology of C. fraxinea species is still unknown, so it is necessary to continue and make further research, to provide disease management and control measures.

Keywords

common ash; narrowleafed ash; dieback; C. fraxinea; necrosis; discoloration; telemorph

Hrčak ID:

91428

URI

https://hrcak.srce.hr/91428

Publication date:

31.10.2012.

Article data in other languages: croatian

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