Evaluation of Fusarium as potential biological control against Orobanche on Faba bean in Tunisia.

A total of 149 fungal strains identified as Fusarium were isolated from infected Orobanche crenata Forsk. and Orobanche foetida Poir. plants. Their pathogenicity and virulence were assessed in Petri dish assays using lentils as the medium. Ten isolates were found to reduce the number of tubercles attached to the host plant. Among them, two isolates that caused necroses on tubercles of Orobanche in the Petri dish assays were identified as Fusarium F6 and F10. They reduced the number of tubercles of O. crenata by 97% and 98%, respectively. Inoculums of F6 and F10 were produced on barley grains and were tested in sterilized and non-sterilized soil in separate pot experiments, using O. crenata and O. foetida as parasitic plants. Both isolates reduced the number of O. crenata and O. foetida by 68% and 88%, respectively, and their dry matter by 82% to 88%. A similar experiment conducted using formulated inoculums of the two isolates showed that the formulation improved the efficiency of the fungi, and reductions in the number and dry matter of tubercles to 100% were observed. These results suggest that Fusarium isolates have the potential to be used as biological control agents against O. crenata and O. foetida on faba bean in Tunisia.