Extreme levels of Nasonovia Ribisnigri aphids create “serious challenge” for British lettuce growers, with an estimated 30 million unharvested heads likely costing growers £10 million over the current four-week period
British leafy salad growers are experiencing record numbers of aphids in 2026 lettuce crops, according to the British Leafy Salad Association (BLSA).
The association reported that extremely high levels of Nasonovia Ribisnigri (Nas) have presented “a serious challenge for growers”, with crisphead, romaine and iceberg lettuces expected to be the worst hit.
Warm and dry weather over the summer has created ideal conditions for aphids in all the major growing UK regions, with other countries such as Germany, France, Italy and Spain also experiencing pest pressure.
Dieter Lloyd, spokesperson for the BLSA, said: “For the current 4 week period, there’s 30 million heads of lettuce being essentially left behind. The cost of that to the growers is £10mn.”
This follows last season, which was also heavily affected by pest activity as a result of prolonged warm, dry weather.
“If you have one aphid on day 1, by day 14 you’ve got 67,000,” Lloyd explained. “Once the aphids bloom once in June, then the population collapses, and then in August and September it blooms again.”
“This year it’s significant,” he continued. “It certainly hasn’t been as bad as this for the last 20 years.”
However, Lloyd emphasised that the pest pressure has been concentrated within the last phase of the British season, with British lettuce having been previously available this season.
“The UK grows over a half a billion heads a season, between May and September, so that puts in context the scale of the loss,” he said. “It’s not good but it’s not the entire year’s crop.”
The BSLA said it has continued to coordinate activity with growers, breeders, researchers and policymakers to accelerate research efforts.
This has included collecting data to track aphid development, optimising current tools and crop protection practices, trialling new control methods and collaborating with plant breeders and policymakers.
“Growers have to date, in collaboration, invested £80,000, significant time, land area and growing resources to industry trials to identify and improve practical evidence-based solutions,” the association stated.
However, with only last season’s pest activity data available, Lloyd cited this as a potential barrier to research and development. “We’ve only got two years’ worth of data, and we’re still working on collating that […] It’s a long, hard process of sitting and counting aphids,” he said.
Developing solutions will be a long-term, collaborative effort, Lloyd added. “It’s not a one shot deal - it’s a combination of working with all the different stakeholders to establish what kind of treatments we are allowed to use and when we are allowed to use them.”
