Evaluation of single annual applications of sterol-inhibiting fungicides for control of pine twisting rust

Six sterol biosynthesis inhibiting (SBI) fungicides - cyproconazole, flusilazole, flutriafol, tebuconazole, triadimefon, and triadimenol - were tested against Melampsora pinitorqua, the causal agent of pine twisting rust. Triadimefon and cyproconazole provided the highest level of control in seedling and cut-shoot bioassays. At 500 mg a.i./L, 2-4 wk of protective activity and at least 5 days of curative activity were observed. Cyproconazole appeared much more fungitoxic than triadimefon toward seven ectomycorrhizal fungi (.)