9 August 2022 News
For the first time, discovered in 1955 and described in 1967 as a novel forma specialis, Fusarium oxysporum f. sp. lactucae (Fol) is the pathogen causing "Fusarium wilt", a disease affecting lettuce. Fusarium is one of the most common plant diseases of lettuce, which damages lettuce's roots through covered and open cultivation, resulting in significant yield loss or even complete crop failure.
Race 1 was identified in 1967 in Japan and then in the USA, Iran, Taiwan, South America, and Europe. Japan also identified races 2 and 3 in 2001. Taiwan is the only country to report on them now.
In 2016 a new Fusarium oxysporum f. sp. lactucae race 4 was described. Fusarium's new race poses a severe threat to European growers and breeders, which is why harmonisation was necessary.
ISF has proposed a new differential set to their Disease Resistance Terminology Working Group (DRT WG) to differentiate this new race. Using this harmonised protocol, Enza Zaden has identified a significant part of our Lettuce assortment to be High Resistant to Fol:4.
The interpretation rule is to have 3 levels of resistance: susceptible, intermediate resistance and high resistance.
Interpretation rule and controls for evaluation of resistance lettuce to Fol:4
Reference isolates for Fusarium oxysporum f. sp. Fusarium oxysporum f. sp. lactucae race 4: After testing several isolates by all breeding companies active with lettuce, the isolate collected in the Netherlands and published by Gilardi et al., 2017 (a new race of Fusarium oxysporum f. sp. lactucae of lettuce. Plant Pathol. 66, 677-688. Doi: 10.1111/ppa.12616) was chosen as a reference isolate.
Please get in touch with your local sales representative for more information about our varieties and their resistances.