P-541 - Fol Race Characterization from Salinas Valley “The Salad Bowl of the World” & Identifying Source of Resistance against Fol Race 1 and Fol Variant

Fusarium wilt of lettuce is a soil-borne disease caused by the fungus Fusarium oxysporum fsp. lactucae (Fol) that affect the growth and development of lettuce. There are currently four known races of Fol worldwide, and only Race 1 is present in the US. In recent years, several lettuce fields in Salinas Valley “The salad bowl of the world” have been affected by Fol resulting in a severe monetary loss for growers. Thus, growers wanted to know which Fol Race is present in their fields and if there are any lettuce cultivars resistant to Fol races collected from Salinas Valley. Out of the 24 Fol isolates collected from eight different commercial fields from Salinas Valley, 18 were Race 1, and three were Fol Variant type. Out of 30 lettuce lines screened for Fol race 1 (PAS-213) and variants (Fol-2441 & Fol-0916), 13, 16 & 17 were resistant to PAS-213, Fol-2441, & Fol-0916, respectively. Two lettuce cultivars showed resistance to all three Fol isolates. Lettuce breeders will use this information to develop lettuce cultivars to help Salinas Valley lettuce growers fight against Fol Race 1 and Fol variant.