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ŠUMARSKI LIST 3-4/2019 str. 9     <-- 9 -->        PDF

Mycobiota in the seeds of narrow-leaved ash (Fraxinus angustifolia Vahl)
Vrste gljiva u sjemenu poljskoga jasena (Fraxinus angustifolia Vahl)
Jelena Kranjec Orlović, Ivan Andrić, Ida Bulovec, Danko Diminić
Narrow-leaved ash (Fraxinus angustifolia), currently the most damaged forest tree species in the Republic of Croatia, is suffering from dieback primarily caused by pathogenic fungus Hymenoscyphus fraxineus. Since health status of seeds is very important for future seedling production, objective of this study was to screen narrow-leaved ash seeds for presence of this main pathogen and other potentially parasitic fungi. Seeds were collected from five locations and analysed using three different methods. Results revealed relatively good health status of inspected seeds, with total of 15 different fungal taxa identified in less than 40% of samples and no confirmation of Hymenoscyphus fraxineus presence. Most frequently detected fungi were various species of genus Alternaria and species Sphaerulina berberidis, while other taxa occurred rarely. Although identified fungal species haven’t caused visible symptoms on seeds after one to two months of storage, many of them are known seed pathogens or opportunistic ash (Fraxinus spp.) pathogens and could have a negative effect on seeds after longer period of storage or storage in unfavourable conditions.
Key words: fungal isolation, nested PCR, Alternaria sp., Sphaerulina berberidis
Narrow-leaved ash (Fraxinus angustifolia Vahl), ecologically and economically very important species in lowland forests, is currently the most damaged forest tree species in the Republic of Croatia with 75% of trees having significantly defoliated crown according to the ICP Forests program data for 2017 (Potočić et al. 2018). Existing research revealed that, among other factors, there are several parasitic fungi involved in the decline in roots and stem collars of affected trees (Kranjec 2017), with pathogenic fungus Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz & Hosoya confirmed as the primary causative agent of crown dieback at multiple locations (Diminić 2015, Milotić et al. 2016). Presence of this pathogen responsible for large-scale dieback of common (Fraxinus excelsior L.) and narrow-leaved ash throughout Europe has been confirmed in roots, stems, branches, shoots, petioles and leaves of both tree species (Kowalski 2006, Gross et al. 2014, Chandelier et al. 2016), but also in the symptomatic and visually healthy seeds of common ash from Latvia and Sweden (Cleary et al. 2013, Hayatgheibi 2013, Marčiulynienė et al. 2018).
Yield and health status of narrow-leaved ash seeds are of great importance in the Republic of Croatia, since they are