Antagonistic Interactions between the Foliar PathogenBotrytis fabaeand Isolates ofPenicillium brevicompactumandCladosporium cladosporioideson Faba Beans

The potential ofPenicillium brevicompactum(isolates MX1.F62, MX1.L32, MX1.L33, and MX1.L34) andCladosporium cladosporioides(isolate MB2.F45) from foliage samples collected from faba bean crops (Vicia faba) was assessed for biological control ofBotrytis fabae(chocolate spot) usingin vitroandin vivoscreening. Significant reductions in the radial growth ofB. fabaewere observedin vitroin dual cultures with clear zones of inhibited growth, as well as discoloration of the pathogenʹs mycelium. Spore suspensions of isolate MB2.F45 reduced infection by 54 and 74% on bean plants when applied either 2 days prior to or simultaneously with conidia ofB. fabae,respectively. Isolates MX1.L32 and MX1.L34 reduced chocolate-spot infection significantly when applied simultaneously with the pathogen. There was also evidence for the action of extracellular metabolites from examination of mycelial growth ofB. fabaein dual cultures, including morphological changes in the formation and size of cells and complete degradation of the fungal hyphae of the pathogen. The cell-free culture filtrate of isolate MX1.L34 reduced germination and germ-tube growth by 79 and 29%, respectively; culture filtrates of isolate MB2.F45 reduced germ-tube growth to 36% of that seen in the control. The active principle(s) in the culture filtrates of both MX1.L34 and MB2.F45 significantly reduced germination and germ-tube development ofB. fabae in vitro.