Pythium tracheiphilum causing leaf rot and wilting in lettuce in Brasília‐DF, Brazil

Abstract

Pythium tracheiphilum is a narrow host range oomycete first described infecting lettuce in Italy. Subsequently, the pathogen was reported in many other countries. From 2015 to 2019, Pythium isolates were recovered from lettuce plants with symptoms of leaf rot, wilting and vascular necrosis, collected from commercial fields in different rural localities of Brasilia‐DF, Brazil. The isolates were identified as P. tracheiphilum based on morphological and molecular genetic analysis. Pathogenicity tests conducted with four P. tracheiphilum isolates confirmed that the isolates were pathogenic to detached leaves of a loose‐hearted lettuce cultivar. This is the first report of P. tracheiphilum infecting lettuces in Brazil.