A new aggressive potato blight strain was detected in Wales and eastern Scotland earlier this year.
The strain, identified as EU 46, can withstand certain fungicides, making it harder to control.
It serves as a stark reminder that nearly 175 years after Ireland’s great famine, this destructive pathogen continues to evolve and endanger crops around the world.
Each year, farmers lose an estimated US$6–7 billion (£4.5–5.2 billion) worth of crops due to this disease.
In Europe alone, direct losses and control costs amount to over €1 billion (£800 million) annually. That includes the cost of expensive fungicide sprays that farmers rely on for protection.
In developing countries, the stakes are even higher. Many smallhold farmers lack resources for intensive disease management. In Uganda, potato blight can destroy up to 100% of a farmer’s crop, endangering livelihoods and local food security.
Just as in the Irish famine, dependence on a single crop is risky. When blight strikes these vulnerable communities, the consequences can be devastating.
After decades of research, blight remains hard to defeat, partly due to the pathogen’s remarkable adaptability. Over the years, Phytophthora infestans (late blight) has repeatedly evolved new genetic strains that overcome both chemical fungicides and the resistant potato varieties bred to fend it off.
The newly identified EU 46 strain is just one example of how quickly blight can develop resistance. In this case, tolerating a key fungicide and showing reduced sensitivity to others.
Meanwhile, environmental changes and global trade create opportunities for wind-blown spores to migrate into new regions. All of this means farmers must remain vigilant; what worked against blight last year might not work today.
After the Irish famine of the 1840s, science eventually identified its microscopic culprit and ways to fight it, but innovation didn’t stop there. Today, researchers and farmers are enlisting cutting-edge technology to stay ahead of blight.
One promising tool is real-time spore detection. Devices like the SwisensPoleno, a monitor developed in Switzerland, can constantly scan the air on farms and spot signs of P. infestans spores as they appear.
In Ireland, I’m leading a project testing this technology out on farms. These sensors rely on advanced imaging and AI to tell blight spores apart from other particles, giving farmers an early warning so they can act before the disease spreads.
Equally, new rapid DNA diagnostics can detect blight more quickly than traditional lab tests which take days to identify new strains. Portable testing kits are bringing diagnostics to the field. My colleagues and I have developed a simple in-field test (like COVID-19 lateral flow tests) that detects specific blight strains from a crushed leaf or air samples in under 30 minutes.
Such tests not only confirm the presence of blight but can tell if the strain is one known to resist certain fungicides. This information allows farmers to choose the right treatment immediately, targeting the pathogen’s weaknesses and avoiding wasted effort.
Farmers are also using data and computer modeling to anticipate outbreaks of the disease, allowing them to act before it can take hold. Sophisticated forecasting systems crunch weather data (temperature, humidity, rainfall) and spore counts to predict when and where blight is likely to strike next.
By pinpointing high-risk periods, these models help schedule fungicide applications more strategically—only when needed, rather than on a fixed calendar. This not only cuts costs and environmental damage by reducing unnecessary sprays, but also slows down resistance development in the pathogen.
A global fight
Defeating potato blight demands international efforts. There’s no wonder drug or magic gene that can eliminate this ever-changing pathogen. Like other experts, I advocate for an integrated pest-management approach.
This combines cultural practices (like crop rotation and destroying infected plant debris) alongside biological controls (naturally occurring microbes, like beneficial bacteria, to help suppress the disease and limit its impact on crops). Judicious fungicide use to reduce the chances of blight taking hold is also effective.
Using technology to leverage real-time data enables farmers to act on early warnings and apply treatments in a targeted way, preserving yields while minimizing environmental damage.
Investing in research and farmer education is essential too—from developing resistant potato breeds to training farmers in remote areas on how to use new diagnostic kits.
The fight against potato blight is global by necessity. An airborne spore originating in one country can hop to another on the wind, as Europe’s experience shows. Likewise, breakthroughs in one lab or farm—whether a new sensor, a resistant potato variety, or an effective organic spray—need to be shared and supported across borders.
International initiatives are putting the latest blight-fighting tools into the hands of farmers around the world. Supporting smallhold farmers in developing countries is especially vital, because they often face blight with limited resources and far more is at stake in terms of food security.
In the mid-19th century, Ireland’s potato-dependent society was caught tragically off guard. Today, we have knowledge, technology and hard-earned lessons on our side.
By embracing an integrated, technology-driven strategy and ensuring it reaches farmers everywhere, that blight cycle could be broken. The continued emergence of strains like EU 46 is a warning, but also a call to action. One that we are now better equipped than ever to answer.
Written by David O’Connor, The Conversation.
