عنوان مقاله [English]
نویسنده [English]چکیده [English]
During the surveys of greengroceries in Urmia during the summer and autumn of 2013, banana fruits with rot symptoms were frequently observed. At first, fruit skin color was changed to brown, then the browning was progressed into fruit flesh and after a short period, all the fruit became brown and rotted. At the surfaces of the rotted fruits, the fungal white mycelium was grown normally and then, small black spots representing fungal acervuli were formed (Fig. A in Farsi section). Fungal isolation was done in two methods: Culture the infected fruit tissues and picking up the conidia directly from acervuli. On the basis of morphological characteristics of the purified fungi, Pestalotiopsis theae with the following characters was identified: Fungal colony on PDA medium at 25ºC and photoperiod of 12 h is white. Colony is fast growing and fills the 80 mm Petri plates after 5 days. After this time, small black pustules (acervuli) are formed at the surface of the colony, at first scattered then aggregated, which contain aggregations of black slimy conidial masses (Fig. B in Farsi section). Conidia are fusiform, staright or slightly curved, 5 celled, with constriction at the septa, 20-25 ×5.5-7 µm, basal and apical cells are hyaline while three median cells are brown to dark brown. At the basal cells of the conidia, there is a hyaline central appendage, 3-8 µm long, but, at apical cells, there are 2-4 appendages, 15-40 µm long. The tips of the appendages are clearly swollen (Fig. C in Farsi section) (Chang et al. 1997; Suwannarach et al. 2013). Pathogenicity tests of the isolates were done on healthy banana fruits in laboratory. For this, fungal inoculation was done both with placing a suspension of 1×106 conidia/ml on the surface of a wounded fruit skin and with mycelial plugs from the edges of the actively growing fungal colonies on the surface of fruits with or without wounding. In controls, water or agar plugs without fungus mycelium was used. Although Pestalotiopsis theae was previously reported from Camellia sinensis (L.) Kuntze in Iran (Ershad 2009), but to our knowledge, this is the first report of Pestalotiopsis theae associated with banana fruit rot.