Unprecedented Aphid Outbreak Puts UK Lettuce Supplies Under Pressure

UK lettuce growers are battling exceptionally high levels of currant-lettuce aphid, with the pest threatening commercially significant crop losses during an already challenging growing season.

The British Leafy Salads Association (BLSA) says crisphead, romaine, and iceberg varieties are among those experiencing the greatest impact, with green-leaved lettuces appearing to be particularly vulnerable compared with purple varieties.

The scale of the losses is already substantial, and could total almost one third of the UK’s lettuce crop, reports GB News.

Growers across several major production regions have described the worst infestation in a quarter of a century infestation as “biblical”.

One producer in East Anglia estimates that around three million heads of lettuce could be lost this season, worth approximately £1 million.

“It’s the worst aphid infestation we’ve had in 25 years,” the grower said.

Heat And Drought Fuel Pest Pressure

The outbreak has developed during a prolonged period of hot and dry weather conditions that have provided favourable circumstances for currant-lettuce aphid populations.

The pest has been reported across the UK’s major lettuce-producing areas, including the Midlands, East Anglia, the South East, and North West.

“There have been extremely high levels of the currant-lettuce aphid, presenting a serious challenge for growers and affecting commercially significant volumes of lettuce crop,” noted a BLSA spokesman.

“The pattern of the aphids’ growth is a peak in late June and again in August and September.”

Aphids feed on plant tissue and sap, which deprives crops of vital nutrients, and can result in affected lettuce becoming unsuitable for commercial sale.

Considering that production continues into mid-autumn, growers are concerned that further pest pressure could lead to further losses.

Shrinking Toolbox

The outbreak also highlights the increasingly limited range of pest control options available to growers.

Previously, neonicotinoid insecticides were used to control aphids in lettuce crops but they have become largely unavailable following European Union (EU) restrictions due to the chemical’s impact on honey bees.

That reduction in available insecticides has increased the importance of alternative control strategies, including varietal resistance.

The BLSA says research is underway to develop lettuce varieties that are better able to withstand aphid attack. 

However, the biology of aphids presents a significant breeding challenge.

Their ability to reproduce asexually, combined with rapid population development and adaptation, can make it difficult for growers and breeders to maintain effective resistance over time.

Trade Implications

Regulatory developments could add another layer of complexity for the UK lettuce sector. 

Closer UK alignment with EU regulations could affect the export of gene-modified crops to continental European markets, although Brussels is expected to revise its regulatory framework by 2028.

The UK lettuce market is already heavily dependent on imported supply. 

Annual consumption is estimated at approximately 200,000 tonnes, of which imports account for around half of total demand.

Aphid pressure is not confined to Britain either. Lettuce production elsewhere in Europe has been affected this year too.

Wider Crop Impacts

The lettuce crisis also comes amid broader weather-related disruption across UK agriculture.

This summer’s drought has affected crops including potatoes and pumpkins, whose yields are set to be significantly below normal levels in some areas.

For lettuce growers, the focus now is on protecting their remaining crops and managing aphid pressure through the remainder of the season.

All the while the longer-term search continues for varieties and production systems that are capable of delivering more resilient crops.