Some lettuce producers saw up to 85% of their crops become unmarketable, figures show
An estimated 30 million British lettuces were left unharvested in September after severe aphid infestations inflicted losses exceeding £10 million on growers, according to updated industry figures.
The British Leafy Salads Association (BLSA) said some businesses had seen as much as 85% of their production become unmarketable, following a second consecutive growing season of exceptionally high pest pressure.
Growers across England's main lettuce-producing regions have been affected, with infestations reaching reported levels of 300,000 to 400,000 aphids per hectare during August and September.
The latest assessment, published on Tuesday 27 October, confirms the scale of losses first forecast by the industry in September and raises fresh concerns about the future of British salad production.
Warm, dry conditions throughout the summer created ideal conditions for populations of the currant-lettuce aphid (Nasonovia ribisnigri) to multiply rapidly.
The pest was particularly troublesome across East Anglia, the Midlands, north-west England, central southern England and the south-east.
According to the BLSA, aphid populations peaked in late June before surging again during August and September, causing widespread problems in wholehead lettuce and baby leaf crops.
The financial consequences have been severe for some individual producers.
One East Anglian grower previously told The Telegraph that he expected to lose three million heads of lettuce, representing approximately £1 million in losses.
He described the infestation as the worst experienced by his business in 25 years.
Dieter Lloyd, spokesperson for the BLSA, previously described the outbreak as potentially the worst in around two decades, although he acknowledged that limited historical data made direct comparisons difficult.
He explained that existing crop protection measures were struggling to cope with the sheer scale of the infestations.
Unlike crops damaged by drought or disease, lettuce affected by aphids may remain largely intact but become commercially unacceptable because of insect contamination.
Even relatively small numbers of aphids can make lettuce unsuitable for sale, particularly when the insects become established deep inside the plant.
According to the Agriculture and Horticulture Development Board (AHDB), currant-lettuce aphids prefer feeding in the centre of lettuce plants, where they become extremely difficult to control once the lettuce has formed a tight heart.
This makes effective treatment challenging, particularly during the final stages of crop development.
Some aphid populations have also overcome resistance previously bred into commercial lettuce varieties, limiting the protection available to growers.
Consequently, farmers can find themselves unable to market crops despite having already invested in cultivation, irrigation, labour and pest control.
Andy Knaggs, head of farming at Agrial Fresh Produce, highlighted the financial consequences in comments published during the outbreak.
He said growers were bearing additional costs through increased monitoring, reduced marketable yields and rejected produce, with some forced to abandon affected fields entirely.
The damage comes after another difficult year in 2025, when growers also experienced unusually high aphid populations.
Although this year's losses were concentrated towards the end of the British growing season, the scale of the outbreak has added to concerns about the resilience of domestic horticulture.
The UK produces more than half a billion heads of lettuce during its main growing season, according to the BLSA, meaning the estimated September losses represent a substantial volume of produce rather than the failure of the entire annual harvest.
The problem has also extended beyond Britain, with high aphid populations reported in major European growing regions including Germany, France, Italy, Spain and the Low Countries.
The severity of the outbreak has prompted greater collaboration between growers, plant breeders, researchers and policymakers in an effort to improve protection against future infestations.
According to the BLSA's latest figures, growers have now invested approximately £200,000 in monitoring, research and field trials across the 2025 and 2026 seasons.
The programme includes studying aphid development, improving existing crop protection practices, testing alternative control methods and working with breeders to develop more resilient lettuce varieties.
The investment represents a substantial increase from the approximately £80,000 in industry-funded trials reported in September.
However, developing effective solutions is proving complicated.
AHDB guidance identifies several challenges, including the insects' tendency to remain concealed inside lettuce plants and the ability of some populations to overcome previously effective varietal resistance.
Growers are therefore examining combinations of crop monitoring, forecasting, resistant varieties, beneficial insects and targeted crop protection measures.
The BLSA is also engaging with regulatory authorities and policymakers to ensure the scale of the problem is recognised and that coordinated support is available.
The outbreak has also raised questions about the availability of domestically grown lettuce during the final weeks of the British season.
British produce normally dominates supermarket shelves during summer and early autumn before retailers increasingly switch to imported supplies as domestic production winds down.
In September, industry representatives warned that severe crop losses could bring forward the seasonal transition towards imported lettuce, including supplies from Spain.
While the precise impact on supermarket sourcing has not yet been established, the outbreak demonstrates how quickly pest pressure can disrupt domestic production.
The financial implications extend beyond the value of the unharvested crops, with affected businesses also facing the costs of additional monitoring, treatment and attempts to protect remaining production.
For producers already operating under pressure from rising costs, losing a substantial proportion of marketable output can have serious consequences for profitability.
With two consecutive seasons of exceptional aphid pressure now behind them, growers face growing uncertainty about the effectiveness of existing control strategies.
Industry representatives are seeking practical solutions that can reduce the risk of further losses before the 2027 growing season.
The challenge will be whether new research, improved crop protection and more resistant varieties can provide sufficient safeguards to prevent millions more British lettuces being abandoned in fields next year.