Characterization of Fusarium species from hot pepper (Capsicum anuum L.) and In vitro antagonistic effect of Trichoderma species

Abstract

Hot pepper (Capsicum anuum L.) is the prominent type of Capsicum species grown in Ethiopia. It is important cash crop to Ethiopian smallholder farmers and an important agricultural commodity which contribute to export earnings. Fusarium wilt caused by Fusarium oxysporum f.sp.capsici is one of the major biotic factors which cause loss of pepper productivity up to 80%. The aim of this study was to isolate pathogenic Fusarium species from pepper plant, determine its pathogenicity and screening Ethiopia hot pepper varieties. Total 48 samples of Pepper plant materials were collected from the major pepper cultivating districts of Jimma Zone. Fusarium isolates characterized morphological and morphometrical, accordingly. Pathogenicity confirmed using Koch postulates. The efficacy of host resistance and biological control in the management of Fusarium wilt was investigated under greenhouse and in vitro dual culture assays, respectively. From the collected samples, based on culture characteristics 96 isolates were clustered in to 8 groups. Thereafter, the isolates were identified as Fusarium oxysporum and Fusarium species using morphological and morphometrical. Of these, Fo1 isolates showed high pathogenicity by causing disease on susceptible cultivar, the rest isolates were recorded weak to moderately pathogenic to the susceptible Mareko Fana variety. Isolate Fo1 was identified as the virulent isolate based on the computed result of disease severity index and Area under Disease Progress Curve. As a result, it was used to evaluate the level of disease resistance in 12 Ethiopian pepper varieties. Based on severity index 16% of Ethiopian pepper varieties were resistance to Fusarium isolate, 67% moderately susceptible and 17% susceptible. Melka Dera and Marko Fana Large pod were considered as promising varieties that showed highly resistance and resistance reaction, respectively. Regarding the efficacy of the biocontrol agents (Trichoderma isolate) on in vitro growth of Fusarium oxysporum and Fusarium species, significant variation has been observed. Trichoderma isolates were 100% effective on isolate Fo3. In conclude, Fusarium wilt damage of hot pepper can be managed using host resistance varieties and biological control, neverthetheless the efficacy and economic validity of these methods should be verified under multi location field studies.