'Aggressive' fungal disease Fusarium wilt has been reported in UK lettuce crops for the first time, with growers urged to check for symptoms as a matter of urgency.
The soil-borne pathogen has previously been found in lettuce crops in mainland Europe, but when a strain of the disease was identified in Lancashire in October, it was the first time it has been confirmed in the UK.
The ‘Race 4’ strain that was identified is a particularly aggressive type of the disease, with no known treatments or resistant varieties currently available.
In the Netherlands growers have been forced to move production to new uninfested glasshouses, or to only grow lettuce in cooler winter temperatures.
Protected and field-grown lettuce crops are worth £142.7 million to the UK economy each year, according to government statistics.
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 sterilisation and environmental control.”
He added: “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 deliver a technical review 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 the industry as the review proceeds.
Jon Knight, head of crop health and protection at AHDB, said: “Despite the strict rules in the UK regarding quarantine and sourcing of plants from other countries to keep the probability of new threats coming in as low as possible, unfortunately the Fusarium wilt has still found a way through.
“We will be collaborating with experts in countries where the disease is already present to collate all relevant information about how to prevent the disease and what control options are available.We will be communicating this to the UK industry as a matter of urgency.”
According to Kim Parker, a crop protection scientist at AHDB, the disease is particularly difficult to control as spores survive for a long time in soil and crop debris.
There are also no effective plant protection products, no available resistant varieties and soil sterilisation has limited effect.
“We are therefore stressing that avoidance is the best strategy,” she said. “We urge growers to review their hygiene measures on both the nursery and with their plant propagator to avoid the disease getting on to their sites.”
Growers who suspect lettuce Fusarium wilt in their crops have been asked to send samples Dr John Clarkson at University of Warwick for free testing.
An AHDB event on practical measures to reduce the risk and impact of the disease will also be held in Lancashire on 14 December.
