Rigorous hygiene practice is critical to prevent the risk of infection from lettuce fusarium wilt, a potentially devastating disease recently detected in UK lettuce crops.

Growers at a recent workshop organised by AHDB Horticulture were told it was essential to carry out risk assessments to identify potential sources of infection. Delegates were also urged to put in place clear hygiene protocols to prevent the disease both getting on to nurseries and spreading between them.

Lettuce fusarium wilt has now been confirmed in the UK on two nurseries in Lancashire since October, 2017 – although earlier outbreaks may have gone undiagnosed. Effective control measures for lettuce the wilt are limited and no varieties resistant to race 4 – the disease strain identified in the UK – are currently available.

Tim O’Neill, associate plant pathologist at ADAS, told growers at the meeting: “All fusarium wilt diseases are difficult to manage, you need to use integrated control rather than individual measures.

“The soil-borne disease can spread easily in the right conditions and growers will need to use efficient cleaning and disinfection methods to reduce their risk of infection. If a glasshouse becomes infected, removal of crop remains and effective soil disinfestation is essential to reduce soil contamination before re-planting lettuce.”

Kim Parker, a crop protection scientist at AHDB, added: “Although the disease is more of an issue under protection in temperate climates like the UK, little is known of the minimum and optimum temperatures required for race 4 to infect, so growers of outdoor as well as protected lettuce crops should be vigilant.”

The University of Warwick is currently conducting a technical review on behalf of AHDB to compile further detailed information on management options, to help minimise the impact on the UK lettuce industry. The full report will be published in early February, 2018.