Large-Scale Atmospheric Dispersal Simulations Identify Likely Airborne Incursion Routes of Wheat Stem Rust Into...

Area of Science:

• Plant pathology
• Aerobiology
• Computational modeling

Background:

• Severe wheat stem rust epidemics, caused by Puccinia graminis f. sp. tritici race TKTTF (Digalu race), have impacted Ethiopia.
• The pathogen was first detected in Ethiopia in August 2012, necessitating an investigation into its origin.

Purpose of the Study:

• To determine the likely airborne origins of fungal spores on regional and continental scales using a case study of the TKTTF race incursion.
• To compare forward and backward time simulations of a Lagrangian particle dispersion model (LPDM).
• To assess the long-term risk of exotic P. graminis f. sp. tritici spore transport into Ethiopia under various scenarios.

Main Methods:

• Utilized a Lagrangian particle dispersion model (LPDM) for simulating airborne spore transport.
• Employed both time-forward and time-backward LPDM simulations.
• Analyzed the impact of release altitudes and urediniospore viability on dispersal patterns.

Main Results:

• Results indicate Yemen as the most probable origin of the TKTTF race, with other potential sources identified in the Middle East and the East African Rift Valley.
• Model simulations align with existing field surveys and phylogenetic data of TKTTF isolates.
• Long-term dispersal trends suggest quantifiable risks of exotic stem rust spore introduction into Ethiopia.

Conclusions:

• Airborne dispersal modeling is crucial for understanding the origins and spread of plant pathogens like Puccinia graminis f. sp. tritici.
• Yemen and the Middle East are identified as significant potential sources for wheat stem rust introduction into Ethiopia.
• Proactive risk assessment and monitoring are essential for managing future exotic pathogen incursions in wheat-producing regions.