Inoculation Techniquesfor Assessing PathogenicityofRhizoctonia solani, Macrophomina phaseolina,Fusarium oxysporumand Fusarium solani on Pepper Seedlings

Abstract

In this study, surveys were carried out during 2015 and 2016 for wilt and root rot diseases caused by Rhizoctonia solani, Macrophomina phaseolina, Fusarium oxysporum, and Fusarium solani in pepper fields in Adıyaman, Diyarbakır, Mardin and Şanlıurfa provinces of Turkey. The purpose of this study was to evaluate the effects of differentinoculation methods (root dip, soil infestation with wheat bran and soil infestation with rice grain) on pathogenicities of R. solani, M. phaseolina,F. oxysporum andF. solani on pepper seedlings. Inoculated pepper seedlings (cv. İnan-3363) were left to grow for three months after transplanting under growth chamber conditions. Inoculation of infective rice-grain was used to test pathogenicity of all four fungi. Root dip inoculation method was used for F. solani and F. oxysporum when the soil was infestedwith wheat branmethod for R. solani andM. phaseolina inoculation. Alltested isolates resultedin thestemand root rot, leaf chlorosis and bruising. To test the pathogenicity of fungi, soil infestation with rice grain inoculation was the most suitable method.All tested fungiinduced similarfoliar symptoms,root rot severityand caused asimilarreduction in dryroot weightswhen rice-grain inoculum wasused. With other inoculation methods, all pathogens similarly affected root rot severity. Whereas, F. oxysporum was the least virulent pathogen among tested fungi affecting foliar symptom severity for fresh root and plant weights, and dry root and plant weights R. solani, M. phaseolina andF. solani weresimilarlyvirulent when these parameters were used. The results of the present study may have a useful connotation to monitor pepper seedlings against these pathogens. In conclusion, we recommend rice-grain inoculation to test pathogenicities of R. solani, M. phaseolina, F. oxysporumandF. solanion various pepper cultivars.