Authors: GÜLCAN YIKILMAZSOY, NECİP TOSUN
Abstract: Potato dry rot disease (Fusarium spp.) is one of the most important fungal storage rots on potato tubers after harvesting. The aims of this study were to identify the Fusarium species that cause dry rot in potato storages, evaluate the most virulent Fusarium species in vitro and in vivo for fungicide sensitivity and determine the susceptibility of the cultivars. In this context, as a result of surveys carried out in potato storages of Ödemiş and Torbalı counties in İzmir province in 2015-2016; Fusarium species obtained from diseased potato tubers were identified as Fusarium sambucinum, F. oxysporum, F. avenaceum and F. equiseti, using morphological and molecular methods. The most virulent species was determined according to the pathogenicity tests. To determine the susceptibility to disease, 13 potato cultivars, commonly stored in the region throughout the working period, were tested against the most virulent Fusarium species. The pathogenicity tests showed variation between the rank order of susceptibility of the cultivars to the most virulent pathogen. Fungicide sensitivity tests have been conducted with the most susceptible among these cultivars. There are not any plant protection products licensed against this disease in Turkey. On fungicide sensitivity tests, fludioxonil, flutolanil, thiophanate methyl, imazalil, fludioxonil + sedaxane, fluxapyroxad and tolclophos-methyl + thiram efficacy were investigated on the mycelial growth of F. sambucinum. In vitro assays; fludioxonil, fludioxonil + sedaxane and imazalil were the most effective fungicides preventing mycelial growth of the pathogen. In addition to chemicals that are effective in vitro tests, efficacy of Bacillus subtilis QST 713 strain 1.34%, Pseudomonas fluorescens strain Pf1 1.5% and 42% carboxylic acid were also evaluated. In vivo tests were conducted with Russet Burbank, Lady Olympia, Granola cultivars and fungicides were applied in two different methods including before and after inoculation. Results of this study indicated that the treatments with fludioxonil + sedaxane had the highest efficacy and treatments before inoculation was more effective.
Keywords: Dry rot, fludioxonil, Fusarium spp., Fusarium sambucinum, potato
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