First Report of Thielaviopsis paradoxa Causing Main Stalk Rot on Banana in Turkey S. T. Demiray, 1 E. Akçalı, 1 A. Uysal, 3 Ş. Kurt 2,3 * 1 Republic of Turkey Ministry of Agriculture and Forestry, Biological Control Research Institute, 01321, Adana, Turkey 2 Department of Plant Protection, Faculty of Agriculture, Hatay Mustafa Kemal University, 31040, Hatay, TURKEY 3 Centre for Implementation and Research of Plant Health Clinic, Hatay Mustafa Kemal University, 31034, Hatay, TURKEY Banana (Musa acuminata L.) is a high value tropical fruit worldwide and increasingly important crop for domestic consumption in Turkey for over a century. Dwarf Cavendish banana, the most widely planted cultivar, has been grown along the Mediterranean coast with annual production of more than 300,000 tonnes. In the early spring of 2018, a serious fungal like rot symptoms was observed on the banana cv. Grande Naine in Silifke district (36°22'17.65"N / 34° 1'47.99"E) of Mersin province, Turkey. The incidence of this disease increased from 5 to 18% during the two consecutive years following the original outbreak. Initially, symptoms on pseudostem were small, irregular, brown lesion, which gradually enlarged and developed from the outside to the inside. The infection resulted in pseudostem rot and eventually plant collapse, but most of the banana leaves were still green. As the disease progressed, cross-sections of infected trunks exhibited tissue discoloration. For fungal isolation, affected banana tissues were surface-disinfected with 1% sodium hypochlorite (NaOCl) solution for 3 min, rinsed twice in sterilized distilled water, and blotted dry on sterilized filter paper. Disinfested pieces were transferred on potato dextrose agar (PDA) and incubated at 25°C for 7 days under a 12-h light/dark photoperiod. Fungal colony from single spores emitting a strong odor on PDA was initially white and downy, rapidly became black and velvety after 7 days of incubation. The fungus produced conidiophores usually individual, straight and from hyaline to pale brown with terminal conidia bearing cells through which conidia were borne in chains. The conidia were cylindrical and hyaline to pale brown, thick walled, smooth or in chains and 5.2 to 14.6 x 3.5 to 5.6 µm (n=40). Chlamydospores were oval, dark brown, thick walled, 7.1 to 18.2 x 4.7 to 12.3 µm (n=20), forming in terminal chains. These morpho-cultural characteristics were generally consistent with those reported for Thielaviopsis paradoxa (De Seynes) Höhn. (Morgan-Jones, 1967; Ellis, 1971). For Page 1 of 3