ISOLATION, IDENTIFICATION AND PATHOGENICITY OF BOTRYOSPHAERIACEAE AND PHAEOACREMONIUM SPECIES ASSOCIATED WITH DECLINE OF PRUNUS SPECIES IN IRAN

Abstract

Between 2011 and 2013, a field survey was undertaken on stone fruit trees in four provinces of Iran to determine the fungal trunk pathogens associated with decline diseases. Wood samples were collected from branches of apricot, peach, cherry, sour cherry and greengage trees showing yellowing, dieback, defoliation, canker, gummosis, decline and internal wood discolouration. Five Phaeoacremonium species, including Phaeoacremonium minimum, P. parasiticum, P. viticola, P. tuscanum and P. krajdenii and six species of Botryosphaeriaceae, namely Diplodia seriata, D. mutila, Neofusicoccum parvum, Botryosphaeria dothidea, Spencermartinsia viticola and Lasiodiplodia theobromae, were isolated and identified based on morphology, culture characteristics and DNA sequence analyses. Pathogenicity tests of candidate fungi were conducted by artificially inoculating detached shoots of all host species with a pathogen-colonized agar plug then covered with Parafilm. 30 days post inoculation, the length of the necrotic wood lesions was measured. Neofusicoccum parvum was the most virulent among the six Botryosphaeriaceae species tested. Of Phaeoacremonium species, P. parasiticum produced the longest necrotic lesions on all inoculated hosts. The following are first reports from this study: (i) P. tuscanum on peach trees; (ii) L. theobromae, B. dothidea, and P. krajdenii on apricot trees; (iii) B. dothidea, S. viticola, D. seriata, D. mutila, P. parasiticum, P. viticola and P. minimum on cherry; (iv) D. seriata, P. minimum and P. parasiticum on sour cherry and (v) S. viticola, L. theobromae and D. seriata on greengage. Phaeoacremonium krajdenii has not yet been reported from Iran and the present study is the first report of this species in this country.