Sesamol (3,4-methylenedioxyphenol) at 2.5 mM inhibited growth of Fusarium moniliforme by about 40% and lipid accumulation by 35%. Gibberellin (GA(3)) accumulation was increased by 20-fold, to 63 mg g(-1) biomass, in the presence of sesamol indicating that the acetyl-CoA destined for fatty acid biosynthesis was now being switched into secondary metabolite (GA(3)) accumulation. Synthesis of other metabolites from acetyl-CoA, such as bikaverin and carotenoids, though were not increased in the presence of sesamol. Metabolic switching is therefore feasible by judicious use of selected inhibitors that can thus block primary metabolic routes but which do not affect secondary metabolites.