Papyracillic acid is a fungal metabolite and a derivative of penicillic acid originally isolated fromL. papyraceumand has antibiotic, antifungal, and phytotoxic activities.1,2It is active against the bacteriaX. campestrisandB. subtilisand the fungusC. tropicalisin a disc assay when used at a concentration of 5 μg/disc.2Papyracillic acid (1 mg/ml) induces necrotic lesion formation in a panel of 10 plants.