Efficacy of a compound based on canola oil as a fungicide for control of grapevine powdery mildew caused by Uncinula necator

A replicated shadehouse experiment demonstrated that a canola oil derivative gave good control of the important grapevine disease, powdery mildew (caused by Uncinula necator). Repeated inoculation of potted vines with U. necator lead to severe foliar infection in the unsprayed control treatment. Repeated sprays of the canola oil derivative at rates of 2.0 and 5.0 mL (formulated product) per L prevented the development of foliar symptoms as effectively as either wettable sulphur 2 g (formulated product) per L or fenarimol 0.2 mL (formulated product) per L at label rates. On the final assessment date, when the untreated control vines were very heavily diseased, the lowest rate (1 mL/L) of canola oil derivative gave significantly (P < 0.05) poorer disease control than the other fungicide treatments though symptoms were significantly (P < 0.05) less severe than in the control. No phytotoxicity was observed in any treatment.