By Lukie Pieterse, Potato News Today

Climate change is not just moving isotherms on a map – it is quietly rewriting where, when, and how hard potato diseases hit. Late blight, virus complexes, bacterial wilts, and nematodes are all responding to new temperature and moisture patterns faster than registration labels, spray programs, and seed-certification rules can adapt. The risk map is being redrawn in real time, while much of the industry is still working from last decade’s playbook.

This feature looks at how disease baselines are shifting, what new surveillance tools can (and cannot) do, how chemistry and resistance are evolving, and where breeding and economics intersect as growers try to stay ahead of a moving target.

Changing baselines – new windows for late blight, blackleg, viruses, and nematodes

For much of the modern potato era, disease management has relied on relatively stable expectations:

• Highlands were “safer” for virus risk.
• Certain regions could assume low pressure from potato cyst nematodes (PCN).
• Late blight risk followed predictable cool, wet windows.

Those assumptions are now under strain.

Late blight windows are stretching and shifting.

Modeling work on potato late blight under different climate scenarios shows that risk is not changing uniformly. In some cooler highland regions, warming temperatures can push conditions closer to the optimum for Phytophthora infestans, increasing the frequency of blight-conducive days. In other, already warm regions, further warming can reduce risk slightly if conditions move beyond the pathogen’s preferred range – but often only if planting dates and cultivars are adjusted accordingly.

In Europe, network data from EuroBlight and associated projects point to continued high late blight pressure in recent seasons, with aggressive genotypes such as EU_43 and others spreading across multiple countries and driving intensive sampling and control efforts.

Virus risk is no longer “locked” to traditional seed areas.

Historically, northern climates like Scotland leveraged cool, aphid-unfriendly weather to keep virus levels low in seed crops. That buffering effect is weakening. Scottish and broader UK work now reports:

• Higher virus levels in seed crops than seen in decades.
• Shrinking availability of effective aphicides due to resistance and regulation.
• Warming seasons that lengthen or intensify aphid flight periods.

At the same time, studies on aphid and virus epidemiology suggest that temperature shifts will not always linearly increase virus pressure. In some cases, extreme heat waves can reduce vector survival or reproduction, even as milder warm periods extend activity earlier in the season. The net result is more variability – and a harder forecasting problem.

Nematodes are marching into new territory.

For PCN, climate models and machine learning ensemble approaches show a clear signal:

• Large portions of the globe are already suitable for one or both major PCN species.
• Warming scenarios to mid-century are expected to expand the suitable range northward and increase the number of generations in some high-latitude regions.

That alters the logic of what is considered a “low risk” rotation system. A region that historically cycled PCN down with long grass or cereal breaks may find that higher soil temperatures compress nematode life cycles, allowing populations to bounce back faster between potato crops.

Blackleg and bacterial wilts are exploiting new niches.

Rainfall extremes – either prolonged wetness or intense events around planting and early growth – favour blackleg complexes and latent infections of bacterial wilt in highland seed zones, which may later blow up when tubers are planted at lower, warmer altitudes. Some East African and Andean work suggests that warming could shift bacterial wilt risk upslope into previously safer seed areas, undermining the basic logic of “clean highland seed feeding lowland ware”.

The net story: the old mental map of “high risk” and “low risk” zones is blurring. Growers and regulators who rely on historic categories – virus-safe, PCN-free, low-blight regions – are increasingly surprised by out-of-place problems.

Diagnostic advances – from hotspot maps to handheld tests

The good news is that surveillance capacity is finally catching up to the complexity. Disease diagnostics for potatoes are in the middle of a quiet revolution.

Smarter, denser monitoring grids.

• European networks like EuroBlight have built continent-scale datasets on late blight genotypes, resistance profiles, and outbreaks, offering an almost real-time view of how the pathogen evolves and moves.
• Aphid monitoring networks in seed regions now combine dozens of suction traps, weekly identification, and rapid data sharing to map virus pressure more precisely in time and space. Companies like Albert Bartlett are partnering with research labs to treat aphid surveillance as a strategic asset, not just a background service.

These systems allow hotspot mapping of virus and blight risk that would have been unimaginable 20 years ago.

Remote sensing and decision support systems.

On the canopy side, high-resolution satellite imagery, drone flights, and machine learning models are increasingly used to:

• Detect early blight or late blight signatures before they are easily visible from the ground.
• Feed risk indices into decision support systems (DSSs) that advise on whether the next fungicide spray should be brought forward, delayed, or changed in chemistry. Projects like NEGFRY and other blight DSSs in Europe are testing how much yield and fungicide can be saved by responding to real disease risk rather than calendar dates.

The challenge is not only technical performance, but trust and usability. Growers will only change a spray interval if the system earns its keep over multiple seasons.

Field-level diagnostics.

On the seed and soil side, portable diagnostic tools are moving more decisions from distant labs to the farm gate:

• LAMP and PCR-based kits for viruses and bacterial pathogens offer same-day answers on whether a lot is clean enough to plant or sell as seed.
• PCN testing remains largely lab-based, but automation and improved protocols are shortening turnaround times – crucial as more fields in new regions fall under quarantine rules.

Where these tools are used rigorously, they provide a new kind of “label”: a real-time health label on a seed lot or field, as opposed to a static legal label printed years earlier. The bottleneck is less technology than economics and training – particularly for smallholders and emerging seed systems.

Chemistry and resistance – fewer actives, faster evolution

If climate is pressing from one side, chemistry and regulation are pressing from the other.

Late blight fungicide portfolios are under pressure.

Across Europe and beyond, the combination of:

• Regulatory withdrawal or restriction of multi-site fungicides such as mancozeb,
• Rising concern over resistance to key single-site fungicides in dominant late blight genotypes, and
• Policy moves under the EU Green Deal to reduce overall pesticide use and risk,

has thinned spray program options and raised the stakes on resistance management.

Newer fungicides and biologicals are entering the market, but many have narrower spectra, shorter residual activity, or more complex use conditions. The practical result is more attention to:

• Mixing and alternating modes of action.
• Matching product choice to risk windows highlighted by DSSs.
• Tightening spray intervals under high-pressure conditions.

In high-value seed or processing crops, that can mean higher costs even when total number of applications is stable, simply because the old “cheap backbone” chemistry is gone.

Virus management is squeezed between aphid resistance and product withdrawals.

Aphid-borne viruses such as PVY and PLRV already cost the European sector close to 200 million EUR per year in lost yield and treatment costs.

Modern virus programs must now juggle:

• Aphid populations that have evolved resistance to several insecticide groups.
• Tightened restrictions on neonicotinoids and other systemics.
• Public and regulatory pressure to reduce broad-spectrum chemistries.

That shifts emphasis towards non-chemical levers: tolerant varieties, stricter seed standards, roguing strategies, trap crops, mulches, and landscape-level management of virus reservoirs.

Nematode control is moving away from “big hammer” nematicides.

PCN management has already seen the loss or severe restriction of several fumigant and non-fumigant nematicides. In many regions, tools now revolve around:

• Longer rotations and non-host crops.
• Resistant or tolerant varieties.
• Bio-nematicides and soil health improvements aimed at boosting antagonistic organisms.

Under climate change, those softer, slower tools are being asked to manage faster PCN life cycles and expanding geographic ranges. That is a mismatch unless breeding and rotation discipline keep pace.

Breeding responses – resistant varieties chasing moving targets

If chemistry is about defending this year’s crop, breeding is about changing the baseline risk over the next decade. Here, there is genuine progress – but also lag.

Stacking resistance for late blight and bacterial wilt.

The International Potato Center (CIP) and partners have spent years mining wild potato relatives for genes that combine:

• Resistance to late blight.
• Tolerance or resistance to bacterial wilt.
• Heat or drought tolerance for future climates.

Recently, new varieties such as CIP-Asiryq and related lines have been released or piloted in several regions. These cultivars aim to:

• Offer strong field resistance to aggressive late blight races.
• Maintain yield and quality under more variable weather.
• Fit both fresh and processing markets where possible, to widen adoption.

National programs in China, Europe, Africa, and Latin America are also investing in climate-resilient, disease-resistant potatoes, often combining classical selection with marker-assisted breeding and, in some cases, gene editing.

The adoption gap.

The bottleneck is rarely the existence of interesting material – it is the speed with which:

• Candidates are tested under real farm conditions across diverse environments.
• Processors and retailers accept new varieties into contracts and specifications.
• Seed systems ramp up volumes without compromising health status.

Where certification rules are built around specific named cultivars, disease-resistant newcomers can face a paradox: they are bred to reduce disease risk, but slowed down by systems designed around the older risk profile. Climate change makes that lag more costly.

Resistance is not a permanent shield.

Even well-designed resistance can be eroded if used in a narrow genetic base, across large areas, without rotation of resistance genes or stacking strategies. Late blight has repeatedly shown its ability to overcome single resistance genes; PCN populations can shift species dominance or virulence profiles; viruses evolve into new strains that partially escape host resistance.

Breeding programs are responding with:

• Multi-gene (pyramided) resistance.
• Diversified portfolios rather than single “mega-varieties”.
• Closer integration with epidemiological monitoring, so resistance breakdown is spotted early.

The core reality remains: by the time a new variety is widely planted, the climate and pathogen populations it was designed for may already have shifted.

Economic stakes – spray costs, rejected loads, and trade friction

Behind the biology sits the ledger. Disease shifts driven by climate change are already turning up in farm accounts and trade statistics.

Late blight alone carries a multi-billion-euro price tag.

Estimates for late blight suggest:

• Roughly 900–1000 million EUR per year in costs (control plus losses) in the EU alone.
• Global annual costs running into several billion dollars when control costs and yield losses are combined.

Those figures pre-date full climate-change impacts. As pressure increases in some regions and control options narrow, the cost curve steepens.

Virus downgrades hit the seed premium – and everything downstream.

Virus issues are increasingly visible as:

• Seed crops downgraded from higher to lower categories (or rejected outright) following post-harvest tests.
• Ware crops underperforming because tolerated virus levels quietly climb over time.

In practical terms, a single season with unexpectedly high virus incidence can:

• Erode the reputation of a seed region.
• Trigger tighter import requirements from trading partners.
• Force processors and retailers to scramble for alternative supply when quality slips.

PCN and quarantine rules can strand land value.

Once PCN is detected above threshold, fields can face:

• Lengthy restrictions on planting host crops.
• Mandatory control or soil sampling measures.
• Reduced rental or sale value because of lost flexibility.

Climate-driven expansion of PCN-suitable zones effectively extends this “hidden liability” to more farms, particularly at higher latitudes.

The compounding effect of climate volatility.

Overlay disease with more volatile yields – driven by droughts, heat waves, or floods – and the economic sensitivity increases:

• In tight margin years, an extra two fungicide sprays or a 5 % yield hit from disease can be the difference between profit and loss.
• For processors, unreliable supply magnifies factory downtime and contractual penalties.
• For exporters, a single high-profile disease interception at the border can trigger new phytosanitary requirements across an entire origin country.

In other words, disease risk is not a side issue in the climate story – it is central to whether potato systems stay bankable.

What a climate-smart disease strategy looks like in 2025

So what does “keeping up with diseases that move faster than labels” actually mean in practice? A few themes are emerging across leading production regions.

1. Treat risk maps as dynamic, not fixed.

• Regularly update late blight, virus, and PCN risk assessments using the latest climate and surveillance data – not just historic averages.
• Revisit assumptions about “virus-safe” or “low-risk” areas every few years, particularly for seed production zones.
• Integrate DSS outputs and hotspot maps into seed region policy and certification strategies, not only into individual farm decisions.

2. Align labels, regulations, and real conditions.

Plant protection product labels, MRLs, and certification rules are inherently conservative and slow to change. That is appropriate from a safety standpoint, but dangerous if climate-driven disease risk outruns them. Pressure is building for:

• Faster but science-based updates to application windows, dose ranges, and resistance management guidance as new genotypes emerge.
• Regulatory frameworks that support rapid approval of genuinely safer, more targeted products (including biologicals) when older actives are withdrawn.
• Seed certification standards that reward genuine reductions in disease risk – for example, virus incidence thresholds aligned with current epidemiology, not legacy numbers.

3. Invest in surveillance as infrastructure.

Robust disease and vector monitoring should be treated like rural broadband or roads – shared infrastructure, not an optional extra. That means:

• Public-private partnerships to fund trap networks, lab capacity, and data platforms.
• Standardised protocols for typing late blight, PCN, and virus variants so trends are comparable over time.
• Making interpreted risk information accessible to growers, not just researchers.

4. Bring breeding, management, and markets into the same room.

Climate-driven disease risk cannot be solved by breeders, chemists, or growers alone. Regions that are getting ahead tend to:

• Involve processors and retailers early in discussions about adopting new resistant varieties, so contracts and specifications do not lag behind breeding progress.
• Tie disease-risk metrics into sustainability and climate narratives in a way that resonates with consumers and regulators (for example, “low-spray, late blight-resilient” chips).
• Co-design IPM packages where fungicide choice, planting date, irrigation, and variety are planned as a system rather than tweaked one at a time.

5. Accept that uncertainty is now part of the job – and plan accordingly.

The most realistic forecast is not that disease pressure will simply go “up” or “down”, but that it will become more variable, with more surprises: new strains, odd-year outbreaks, unusual timing.

Growers and supply chains that stay resilient tend to:

• Build financial buffers for bad disease years.
• Diversify rotations, market outlets, and, where possible, growing regions.
• Use multi-year data from DSSs and monitoring programs to refine strategies, rather than judging them on a single season.

Conclusion

Climate change is, at its core, a moving target problem, and in potatoes that moving target shows up first and most brutally in disease patterns. The real test for the industry now is whether it can move from fixed recipes to adaptive systems – where fungicide labels, spray programs, seed standards, variety lists, and even regional risk maps are reviewed, updated, and stress-tested as routinely as financial plans.

This demands closer links between growers, researchers, regulators, and the supply chain, with surveillance data and on-farm experience feeding back into policy and practice every season, not once a decade.

If the sector can build that culture of continuous adjustment, then late blight, viruses, blackleg, and nematodes remain tough but manageable adversaries. If it cannot, the biology will simply outrun the rulebook, and the cost will be paid in lost yield, stranded land, and eroded trust in the potato’s reliability as a crop.

Selected sources for further reading

1. Sparks, A. H. et al. Climate change may have limited effect on global risk of potato late blight. RTBMaps / CIAT. https://gisweb.ciat.cgiar.org/RTBMaps/docs/PotatoLateBlight.pdf
2. EuroBlight network and monitoring updates. Aarhus University. https://agro.au.dk/forskning/internationale-platforme/euroblight
3. Copa-Cogeca et al. EU potato sector confronts late blight threat – action plan and economic impact. Potato News Today / EU Action Plan documents. https://potatoeswithoutborders.com/2024/06/04/eu-potato-sector-confronts-late-blight-threat-copa-cogeca-unveils-comprehensive-action-plan/
4. Meno, L. et al. Opportunity of the NEGFRY Decision Support System for late blight control. Agriculture (2024). https://soildiveragro.eu/wp-content/uploads/2024/04/agriculture-14-00652.pdf
5. SEFARI. Save our tatties! New approaches for virus control in Scottish potato crops. https://sefari.scot/research/save-our-tatties-new-approaches-virus-control-scottish-potato-crops
6. Dupuis, B. et al. Economic impact of potato virus Y (PVY) in Europe. Potato Research (2024). https://link.springer.com/article/10.1007/s11540-023-09623-x
7. He, Y. et al. Predicting potential global distribution and risk regions for potato cyst nematodes. Scientific Reports (2022) and follow-up machine-learning work (2024). https://www.nature.com/articles/s41598-022-26443-0
8. Dutta, T. K. et al. The pervasive impact of global climate change on plant–nematode interactions. Frontiers in Plant Science (2023). https://www.frontiersin.org/articles/10.3389/fpls.2023.1143889/full
9. CIP. Scientists use the potato’s wild relatives to produce climate-resilient varieties. (2018). https://cipotato.org/pressreleases/scientists-use-potatos-wild-relatives-produce-climate-resilient-varieties/
10. CIP / partners. Recent news on blight-resistant varieties such as CIP-Asiryq. PotatoPro and related coverage. https://www.potatopro.com/news/2025/cip-asiryq-new-blight-resistant-potato-boosts-farmer-resilience
11. Naim, Y. B. et al. Replacing mancozeb with alternative fungicides for the management of potato late blight. Plants (2023). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10672005/
12. Tsai, W. A. et al. Perspectives on plant virus diseases in a climate change scenario. Virus Research (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10442010/
13. Zhang, S. et al. Climate change impacts on potato storage. Foods (2024). https://www.mdpi.com/2304-8158/13/7/1119
14. Reuters. China scientists rush to climate-proof potatoes. (2024). https://www.reuters.com/world/china/china-scientists-rush-climate-proof-potatoes-2024-11-27/

Author: Lukie Pieterse, Potato News Today