Fig. 3. Mean zone of inhibition on agar plates caused by Xenorhabdus bovienii (Xb) or Photorhabdus luminescens (Pl) metabolites applied to lawns of Armillaria tabescens. Acetone (the metabolite solvent) and water were applied as controls. Different letters above bars indicate statistical significance (Student–Newman-Keuls’ test, a = 0.05).