FIRST REPORT OF THE OCCURRENCE OF Fusarium avenaceum ON BROAD BEAN (Vicia faba) IN IRAN

During April 2013, Samples of broad bean (Vicia faba L.) plants showing root rot and wilt symptoms were collected from different farms located in Tarom region of Zanjan province. Laboratory observation indicated sporodochium of the genus Fusarium on infected roots. Single spore isolation of the fungus was carried out from sporodochia on infected host tissues. Based on morphological characteristics including; growth features on PDA and CLA media, size and shape of macroconidia and microconidia and other microscopic characteristics, the fungus was identified as Fusarium avenaceum (Fries) Saccardo (Leslie and Summerell, 2006;GerlachandNirenberg, 1982). Growth rate was relatively rapid on PDA. Surface of the colony on PDA was white in color and reddish orange from the bottom of Petri dishes. Abundant pale orange sporodochia formed on PDA and CLA. Macroconidia were long and slender, straight to slightly curved with 3 to 5 septa, apical cell long and tapering, basal cell with dorsal curvature and foot shaped, 42 – 55 (50.3) × 2.5-5 (3.3) µm. Macroconidiaformed in vitro on CLA were longer and narrower than those produced in natural habitat. Microconidia and mesoconidia were fusiform, 1-3 septate, produced singly on monophialides and polyphialides and variable in size. The pathogenicity test of the fungus was carried out on cultivar Barakat in pots containing 1/1/1 (v/v/v) ratio of field soil, sand and compost under greenhouse conditions using wheat inoculum according to Burgess et al. (1994). After 12 days, the inoculated plants showed root rot and wilt symptoms similar to those occurred in the field. F. avenaceum is one of the species causing damage to broad bean in the world. This is the first report of isolation and pathogenicity confirmation of F. avenaceum from broad bean in Iran.