Lipophilic phytotoxins produced by Neofusicoccum parvum, a Botryosphaeriaceae species pathogenic to grapevine, were isolated and identified by spectroscopic methods as (3R,4R)-(-)-4-hydroxymellein, (3R,4S)-(-)-4-hydroxymellein, isosclerone and tyrosol. When assayed for phytotoxicity on tomato plants, all four metabolites showed phytotoxic activity, with (3R,4R)-(-)-4-hydroxymellein and isosclerone the most active. Isosclerone is reported for the first time as produced by a Botryosphaeriaceae species