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Poster: Biology & Disease Mgmt: Chemical Control


Fungicide sensitivity of Phytophthora infestans isolates collected in Colombia
M. PARRA-BASTIDAS (1), L. Cabrera-Villamizar (1), J. Chirivi-Salomon (1), C. Ñústez (2), S. Restrepo (1), G. Danies (1) (1) Universidad de los Andes, Colombia; (2) Universidad Nacional de Colombia, Colombia

Phytophthora infestans, is a major constraint to potato production in Colombia. The disease is present in all regions where potatoes are grown and may cause losses of around 265,000 tons of potatoes per year. Control of late blight in Colombia is mainly achieved by the use of fungicides. Due to the specific mode of action of some of these fungicides and the high selection pressure exerted by the continued use of these products it is likely that some P. infestans strains in Colombia have already developed resistance against some of these systemic fungicides. Therefore, the aim of this study was to determine the sensitivity of isolates collected in potato-producing regions of Colombia to the systemic fungicides dimetomorph, fluopicolide, and propamocarb. Baseline sensitivity was tested in vitro on pea agar media amended with a range of concentrations of each fungicide tested. Dose-response curves and values for the median effective concentration, at which 50% of mycelial growth was inhibited, were determined for each isolate.