Rose downy mildew caused by Peronospora sparsa is a disease of increasing importance for the Co- lombian flower industry. The disease was first reported in the 1970's and, during the last years, its aggressive- ness has increased dramatically. This has meant that an increasing and unacceptable number of fungicide ap- plications are required to control it. This situation has a negative impact on the environment and public health, and requires a program to manage fungicide resistance, including participation of flower growers, fungicide companies, government agencies, and research institu- tions. The aim of this study was to build up a baseline of sensitivity of P. sparsa isolates to fenamidone, a systemic QoI fungicide, in order to support chemical strategies used to control P. sparsa, and specifically those directed to avoid a loss of sensitivity to these fungicides. The results were linked to the presence of point mutations in the cytochrome b gene, which have previously been linked to resistance to these fungicides. Fungicide evaluations showed a high level of sensitivity of P. sparsa isolates to fe- namidone (EC50: 0.51 mg· L -1 ), which was linked to the absence of point mutations G143A and F129L in the cytochrome b gene. A test is currently being designed to monitor QoI fungicide sensitivity in P. sparsa populations in the rose growing regions of Colombia.