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Look out for lettuce Fusarium wilt

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An outbreak of an aggressive disease has been reported in UK glasshouse lettuce crops for the first time and growers are being urged to look out for symptoms to get diagnosis early.

Lettuce Fusarium wilt has previously been found in mainland Europe, but the identification of this strain of the disease in Lancashire, in October this year, was the first time it has been confirmed in the UK. The pathogen was identified as Race 4, which is a particularly aggressive strain with no known treatments or resistant varieties currently available. In the Netherlands, protected crop growers are having to move production to new, uninfested glasshouses, or to only grow lettuce in the winter in cooler temperatures.

According to AHDB Horticulture, although the disease can affect both outdoor and protected lettuce, the immediate worry in the U.K. is the protected industry since that is what has been most affected in NL. Outdoor lettuce has been affected badly in Italy where temperatures are higher, but it is protected lettuce where the risk is currently higher.

John Jackson, Managing Director at Seven Oaks Nurseries, said: “Glasshouse lettuce growers are extremely concerned about the outbreak and their future as lettuce growers. In 40 years of growing lettuce, I have never had a disease that could not be controlled by chemical application, soil sterilization and environmental control.

“If the disease spreads significantly, we may be in a situation, as in Holland, where lettuce cannot be grown in the soil. This would put many growers in a very difficult situation, looking for alternative crops, most of which would need significant capital expenditure at a time when margins are already tight.”

AHDB Horticulture has contracted the University of Warwick to compile 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, but information will be shared with industry as the review proceeds.

Growers who suspect lettuce Fusarium wilt in their crops should send samples for diagnosis. As part of an AHDB project, Dr John Clarkson, at University of Warwick, will accept samples for free testing. Visit; horticulture.ahdb.org.uk/lettuce-fusarium-wilt-and-root-rot for further information.

Photo credit: AHDB Horticulture

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