Sensitivity in vitro of Stemphylium vesicarium to fungicides

Brown spot, caused by Stemphylium vesicarium, is the most important pear fungal disease in Northern Italy and its management relies on frequent preventative applications of fungicides. Dicarboximides (mainly procymidone) are the fungicides most effective against this pathogen but the occurrence of field resistant isolates in the early 1990s led to a reconsideration of other products. S. vesicarium sensitivity to SBIs, dithiocarbamates, anilinopyrimidines, strobilurins, phenylpyrroles and sulphamides was evaluated through inhibition tests of conidial germination, mycelial growth and hyphal elongation. Fenbuconazole, penconazole, ziram and strobilurins showed good efficacy on conidial germination also in isolates resistant to dicarboximides, while the best activity on mycelial growth was obtained with anilinopyrimidines, tebuconazole, flutriafol, difenoconazole and propiconazole. The best hyphal growth inhibition was observed with ziram and fenbuconazole.