2019 ASHS Annual Conference

Fusarium wilt of lettuce caused by the fungal pathogen Fusarium oxysporum f. sp. lactucae (Fol) was first reported in the U.S. in 1990, and is now widespread in California and Arizona. The disease was confirmed on symptomatic plants in Florida displaying wilting and vascular discoloration of the taproot for the first time in 2017. Capable of being seed-borne, it is suspected that the pathogen arrived on infected seed. The major lettuce growing region of Florida, the Everglades Agricultural Area (EAA), has supported the survival of numerous Fusarium pathogens on a variety of crops over the years and there exists the potential for this lettuce wilt pathogen to thrive there. In response to this new threat, University of Florida research and extension personnel began working with local scouts and area lettuce producers to examine prospects for host-plant resistance in Florida adapted varieties, fungicidal control, sanitation procedures, and cultural management options to slow the spread of Fol. Pathogen isolates were collected for pathotyping and the geographical distribution throughout the EAA was recorded. An initial grower workshop was held in the spring of 2018 to educate members of the Florida lettuce industry regarding Fol biology, symptoms, impact elsewhere, and potential mitigation tactics. A post-reflective survey conducted at the conclusion of the grower meeting indicated significant knowledge gain by the attendees. In the fall of 2018, select lettuce growers and crop consultants representing 90% of the 15,000 acres of lettuce farmed in the EAA completed a follow-up survey to determine which, if any, behavior changes were implemented as a result of the previous educational workshop on the Lettuce Wilt pathogen. Adoption of UF/IFAS recommended management strategies designed to limit the spread of Fusarium wilt of lettuce were acknowledged by 63% of the respondents. Among the new practices employed by these lettuce producers are dedicated tools and equipment for fields where Fol is known to be active and sanitization of tools and equipment after use in such fields. These and other management efforts being utilize to slow the spread of Fol by local growers are being evaluated as the 2019 growing season progresses.