A new race of <i>Fusarium oxysporum</i> f. sp. <i>lactucae</i> of lettuce

Abstract

Fusarium oxysporum f. sp. lactucae , the causal agent of fusarium wilt of lettuce ( Lactuca sativa ), occurs in most countries in which lettuce is grown and causes serious economic losses. Three races (1, 2 and 3) of the pathogen have previously been identified on the basis of their ability to cause disease on differential lettuce cultivars, as well as by means of molecular tools developed to characterize different races of this pathogen. Only race 1 has been detected in Europe so far. In this study, two isolates of F. oxysporum , obtained from lettuce plants grown in the Netherlands showing symptoms of wilt, have been characterized by combining the study of pathogenicity with differential cultivars of lettuce and molecular assays to determine whether the isolates are different from the known races of F. oxysporum f. sp. lactucae . This study reports the presence of F. oxysporum f. sp. lactucae for the first time in the Netherlands. The causal pathogen has been identified, using the IRAP ‐ SCAR technique, as a new race of F. oxysporum f. sp. lactucae . Specific primers have been designed to identify this new race.