A new race of Fusarium oxysporum f. sp. lactucae 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.

Nursery treatments with resistant inducers, soil amendments and biocontrol agents for the management of the Fusarium wilt of lettuce under glasshouse and field conditions

“…Fusarium wilt of lettuce, caused by Fusarium oxysporum f. sp. lactucae , is at present the most serious disease of this crop and causes significant losses throughout the world (Gilardi et al, ; Matheron & Gullino, ; Subbarao et al, ). This pathogen, which was first reported in Taiwan (Matuo & Motohashi, ) and in Japan, was discovered in the United States in 1990, where it was named F. oxysporum f. sp.…”

“…In the case of severe disease pressure, which is often present under favourable environmental and cultural conditions, its control is complicated by several factors, including the reduced availability of chemical fumigants for soil disinfestation (Colla, Garibaldi, & Gullino, ; Gordon & Koike, ). Although resistant genotypes are recommended to manage the disease (Garibaldi, Gilardi, & Gullino, ; Gilardi, Demarchi, Gullino, & Garibaldi, ; Matheron, McCreight, Tickes, & Porchas, ; Scott, Kirkpatrick, & Gordon, ), the development and release of new resistant cultivars is complicated by the high variability of the pathogen, which has already differentiated at least four races (Fujinaga et al, ; Gilardi et al, ; Matheron & Gullino, ). Registered, effective fungicides for postplanting soil applications are limited to conventional cultivation and are prohibited in organic farming, thus providing one more reason for the need of environmentally friendly control methods, including the use of resistance inducers, organic amendments and biological control agents.…”

Emerging foliar and soil‐borne pathogens of leafy vegetable crops: a possible threat to Europe

“…Stock seeds should be produced in those areas associated with the lowest disease risk, and the seeds subjected to standardized seed health analysis (Munkvold, ). The availability of good diagnostic tools and early pathogen detection represent the best preventative measures in many cases (Thomas et al ., ), as has been observed for the case of P. cucumerina on wild rocket (Gilardi et al ., ) as well as for formae speciales and races of F. oxysporum from seeds, plants and soil samples (Pasquali et al ., ; Mbofung & Pryor, ; Gilardi et al ., ).…”

“…Moreover, Fusarium oxysporum f. sp. lactucae has also increasingly been observed in lettuce cultivation areas (Matheron & Gullino, ), and has recently spread to the Netherlands (Gilardi et al ., ) and France (Gilardi et al ., ). Like other soil‐borne pathogens, Fusarium wilt is difficult to manage with a single approach and/or with a single product (Katan, ).…”

Intraspecific variability of the fungus Fusarium oxysporum f.sp. lactucum J.C.– causative agent of fusarium Lactuca sativa L.

“…Итак, обнаруженный нами полиморфизм естественной популяции паразита не противоречит известным сведениям о разнонаправленной изменчивости более чем 70 патогенных форм Fusarium oxysporum, включая Fusarium oxysporum f.sp. lactucum [1,14,15]. Так, согласно классическим постулатам, популяция фитопатогена как совокупность особей, входящих в био -и/или агроценоз, проявляет паразитические свойства только при контакте с растением-хозяином.…”