Epidemiology and Control of Phytophthora Infestans in Agricultural Systems

Phytophthora infestans, the oomycete responsible for potato and tomato late blight, remains one of the most destructive pathogens in global agriculture. Its epidemic outbreaks are driven by a combination of asexual sporangial dispersal, occasional sexual recombination and rapid clonal expansion. Environmental factors such as prolonged leaf wetness, high relative humidity and moderate temperatures create conditions favourable to sporangia production and zoospore release. The genetic diversity of field populations varies regionally, with some areas dominated by a few aggressive clonal lineages while others support high diversity and sexual reproduction. Management strategies have traditionally relied on calendar‐based applications of broad‐spectrum fungicides, but the frequent emergence of resistant strains and concerns over environmental impact have spurred the adoption of integrated pest management. This approach combines host resistance, targeted fungicide use, real‐time disease forecasting and pathogen population monitoring. Advances in molecular diagnostics, high‐throughput screening and data‐driven risk modelling are now helping to refine spray timing, guide fungicide choice and detect novel genotypes before they become widespread. Such integrated strategies are essential to safeguard food security and adapt to changing pathogen populations and climatic conditions.

Research from Nature Portfolio

Large-scale surveys of P. infestans populations in India during severe late blight epidemics have identified the migration and sub-clonal diversification of a European lineage, revealing multiple unique multi-locus genotypes and widespread resistance to metalaxyl. This work highlights the need for stringent phytosanitary measures and continuous genetic surveillance to limit further introductions of aggressive lineages. In parallel, comparative analyses of pathogen sensitivity to the QoI fungicide azoxystrobin across Chinese populations demonstrated uniformly low EC50 values and minimal genetic variability in tolerance. The study attributed the low risk of resistance development to the high fitness costs of resistant mutations and suggested that ambient temperature influences fungicide efficacy, offering insights into optimising application under future warming scenarios.

Epidemiology and Control of Phytophthora Infestans in Agricultural Systems publication trend

The graph below shows the total number of articles in epidemiology and control of phytophthora infestans in agricultural systems across all publications each year (not limited to Nature Index journals).

Technical terms

Sporangium: Asexual reproductive structure that releases zoospores under wet conditions.

Clonal lineage: A genetically uniform population derived from a single ancestor through asexual reproduction.

EC50: Effective concentration of a fungicide required to inhibit 50% of pathogen growth in vitro.

Integrated Pest Management (IPM): A holistic approach combining biological, cultural, genetic and chemical controls to manage disease.

Multi‐locus genotype (MLG): The allelic profile of multiple genetic markers used to characterise pathogen diversity.

Aerobiological risk level (ARL): A threshold concentration of airborne sporangia indicating elevated infection pressure.

References

1. Pathogens which threaten food security: Phytophthora infestans, the potato late blight pathogen. Food Security (2021).
2. Large sub-clonal variation in Phytophthora infestans from recent severe late blight epidemics in India. Scientific Reports (2018).
3. Comparative analyses of fungicide sensitivity and SSR marker variations indicate a low risk of developing azoxystrobin resistance in Phytophthora infestans. Scientific Reports (2016).
4. Genetic structure and population diversity of Phytophthora infestans strains in Pacific western Canada. Applied Microbiology and Biotechnology (2024).
5. Methods for Fungicide Efficacy Screenings: Multiwell Testing Procedures for the Oomycetes Phytophthora infestans and Pythium ultimum. Microorganisms (2023).
6. Predicting Daily Aerobiological Risk Level of Potato Late Blight Using C5.0 and Random Forest Algorithms under Field Conditions. Sensors (2023).