Pathogenicity, virulence and in vitro sensitivity of Elsinoe perseae (= Sphaceloma perseae) isolates to different fungicides

Abstract

Elsinoe perseae (= Sphaceloma perseae) is the causal agent of the Mancha purpura or scab in avocado (Persea americana). In this study, the pathogenicity and virulence of E. perseae isolates from different agroecological producing areas of Michoacán, Mexico will be reduced. For this, nursery plants with avocado fruits of Flor de María and Méndez varieties were used. On the other hand, the in vitro sensitivity of chemical fungicides (azoxystrobin, thiabendazole, pyraclostrobin, cyprodinil + fludioxonil and azoxystrobin + propiconazole) and authorized for use in orchards with organic management (copper sulfate, copper gluconate, copper oxychloride and the plant extract Larrea tridentata). The observed symptoms of Mancha purpura in the inoculated fruits were corroborated with those described for E. perseae in avocado. Inoculated fruits Flor de María variety shows the highest susceptibility to the pathogen. The isolates of E. perseae presented different degrees of virulence. The isolates showed different in vitro sensitivity values to the fungicides evaluated in the experiment. The pathogen showed the most sensitivity in vitro to chemical fungicides: thiabendazole and azoxystrobin + propiconazole (100% inhibition), and to those authorized in orchards with organic management: L. tridentata and copper oxychloride (on average 58% inhibition).