Biological control of sesame Fusarium wilt using Trichoderma harzianum in Khorasan Razavi province under in vitro and in vivo conditions

Abstract

Background and ObjectivesSesame is one of the most valuable crops in human nutrition and is cultivated in different regions of Iran, including Khorasan Razavi province. In this plant, various pathogens cause vascular wilt and reduce crop yield. This study aimed to detect the fungal pathogens causing vascular wilt in sesame and control its diseases using the antagonistic fungus Trichoderma harzianum under in vitro and in vivo conditions.Materials and MethodsTwenty-one suspected sesame samples were collected and transferred to the laboratory to be studied using valid morphological identification keys. Media such as PDA, WA, and CLA were used for the isolation, purification, and identification of the fungal samples isolated from the infected sesame plants, respectively. Pathogenicity test was conducted by the root inoculation of sesame plants grown under greenhouse conditions. The biocontrol activity of Trichoderma harzianum (Isolate TR5) isolated from the rhizosphere of sesame roots was evaluated against the pathogenic isolates of Fusarium oxysporum f. sp. sesami under in vitro (dual culture) and greenhouse conditions by the root inoculation of the plants.ResultsAccording to the result, 17 isolates were related to Fusarium oxysporum f. sp. sesami. The pathogenicity test was performed on the sesame plants at the 5-8-leaf stage. All F. oxysporum f. sp. sesami isolates were pathogenic as they revealed a significant difference at p=0.05. The highest level of pathogenicity was noticed for the isolates BA15 and BA16, both with 87.5% wilting, and the lowest pathogenicity was observed in the isolates AN7 and KA33, both with 12.5% wilting on the sesame plants. Regarding the antagonistic properties, the highest inhibition rate in dual culture with T. harzianum was observed for the BA1 isolate with 88.45% mycelial inhibition, while the lowest inhibition rate during interaction with the antagonist was exhibited in the AN2 isolate with 71.33% mycelial inhibition.Moreover, the disease severity reduction rates were different among all isolates of the pathogen tested under greenhouse conditions, and a significant difference was observed at p= 0.05. The highest antagonistic activity of T. harzianum was observed in the BA1, AN7, and K33 isolates with 100% disease severity reduction; however, the lowest activity was related to the AN2 isolate with 54. 54% reduction.DiscussionThe present study indicates that the TR5 isolate belonging to T. harzianum has a high biocontrol potential for controlling vascular wilt on the sesame plants. Consistent with this finding, previous studies have also reported the potentials of Trichoderma spp. for controlling Fusarium wilt in tomatoes, cucumbers, and beans.