Identification of fungi associated with dieback and decline of ash trees in Ardabil

Paripour, Zahra (2020) Identification of fungi associated with dieback and decline of ash trees in Ardabil. Masters thesis, University of Mohaghegh Ardabili.

Text زهرا پری پور - 9645294104.pdf Download (848kB)

Abstract

Research Aim: The Purpose of this study was to identify the fungi associated with dieback and decline of ash trees (Fraxinus excelsior and F. routondifolia) in Ardabil include fungi involving in vascular obstruction and dieback of ash trees and fungi causing leaf spot and root and crown rot as predisposing factors to decline. Research method: During the summer and autumn 2018 and a few cases, in the summer and autumn 2019, after visiting the green spaces of Ardabil and Namin cities, the samples from leaves, branches, trunks, and roots and rarely from the fruit of ash trees showing signs of decline and dieback and without symptoms trees, were collected. After surface sterilized (dipping in 0.5% sodium hypochlorite) and rinsing three times in distilled water) and drying in a sterile filter paper, samples were plated on PDA. Obtained fungal isolates were purified by single spore method and sometimes hyphal tip and then identified using specific culture media and according to morphological and microscopic features using valid mycological keys. The pathogenicity test was performed for several fungal isolates by detached twigs and also pathogenicity on seedlings in the greenhouse Findings: In recent years, the symptoms of dieback and decline have been seen on ash trees in the urban green space of Ardabil. In this research, after studying the morphological and microscopic characteristics of obtained fungi, Alternaria alternata, A. cf. destruens, A. infectoria, Alternaria sp., Chaetomium fimeti, C. megalocarpum, Chaetomium sp., Cladosporium cladosporioides, Cladosporium cf. herbarum, Cladosporium sp., Clonostachys rosea, Cytospora chrysosperma, Diplodia sp., Epicoccum nigrum, Fusarium acutatum, F. acuminatum, F. crookwellense, F. denticulatum, F. equseti, F. lateritium, F. oxysporum, F. solani, F. subglutinans, F. thapsinum, F. verticillioides, Nigrospora oryzae, Nodulisporium sp1., Nodulisporium sp2., Penicillium sp1, Penicillium sp2., Peyronellaea sp., Phialophora cinerescens, Pleospora sp., Sordaria fimicola, Trichocladium cf. amurphum, Trichoderma sp., Melanospora sp., Microascus sp., Microsphaeropsis cf. olivacea and Mucor sp., were identified using valid sources and keys. The results of cut twigs pathogenicity test for three isolates: F. solani, F. oxysporum, and C. chrysosperma after one month showed that discoloration of the skin tissue and browning of the skin and wood of the treated branches occur and pathogenicity test with C. chrysosperma on seedlings in the greenhouse also changed the skin and wood color of seedling treatments and formed pycnidium on them. Conclusion: Several pests and pathogens threats ash tree and leads to weakness and decline, among them, fungal diseases damage significantly. In this study, 200 fungal isolates include 21 genus and 43 taxons (26 distinguished species and the rest as undistinguished) were isolated from the studies ash trees. Three genera Alternaria, Fusarium, and Cytospora ranked first to third of frequency, respectively. Fusarium solani, Cytospora chrysosperma and F. oxysporum with 9.5%, 6%, and 5.5%, had the highest abundance, respectively, and according to the pathogenicity test results, they could be considered as possible causal agent of the decline and dieback of ash trees in Ardabil. Most of the fungal species identified in this study are reported for the first time in the world on ash trees (F. excelsior and F. routondifolia). Fusarium denticulatum and Trichocladium cf. amurphum is a new record to the Iranian mycobiota. Knowledge of mycoflora and fungi associated with ash trees decline in Ardabil green space may greatly assist in management of these diseases.

Actions (login required)

View Item