A novel strain of Fusarium oxysporum from Germany and its potential for biocontrol of Orobanche ramosa

A newly isolated Fusarium oxysporum strain was investigated for its biocontrol potential against the root parasitic weed Orobanche ramosa (branched broomrape). The fungus was found to affect all developmental stages of the parasite. Orobanche seed germination was reduced by 40% in the presence of fungal conidia in vitro. The number of underground tubercles and shoots of the weed was reduced by the fungus by 55% compared with the control and 92% of tubercles were recorded as diseased in root chambers. In pot experiments, soil application of a granular formulation of the fungus resulted in a reduction of number and dry matter of Orobanche shoots by more than 90%. Spraying of a conidial suspension on aboveground Orobanche shoots caused the death of 75% of them within 2 weeks. Data from initial host-range experiments indicate that the isolate is very host-specific, not even attacking shoots of other Orobanche species. Because of these promising results, we conclude that the fungal isolate should be investigated under field conditions and be compared with other Fusarium isolates proposed for biocontrol of O. ramosa.