EFFECTS OF CHEMICALS ON ASCOSPORE PRODUCTION BY LEPTOSPHAERIA MACULANS ON BLACKLEG-INFECTED CANOLA STUBBLE IN SASKATCHEWAN

摘要

Chemical treatment of blackleg-infected stubble was often very effective in inhibiting or eliminating the production of ascospores by Leptosphaeria maculans. Among the most effective fungicides were the ergosterol biosynthesis inhibitors, nuarimol, propiconazole, and triadimenol, which at 0.1 g a.i./L reduced spore numbers by 99-100%. Prochloraz, imazalil, chlorothalonil, and benomyl also significantly reduced ascospore numbers at 0.1 g a.i./L. At 10 g a.i./L, the herbicide glyphosate completely prevented ascospore formation, whereas trifluralin increased sporulation. A role for chemical treatment of stubble for control of blackleg on canola is indicated in light of the trend toward minimum tillage practices by western Canadian producers.