Building Plant Pathogen Surveillance Networks in Sub-Saharan Africa

Trans-boundary pathogens pose an increasing threat to global food security. New strains of old diseases and new diseases colonizing new areas can cause significant crop losses. Pathogens can be highly mobile; spreading by wind, travel or commercial trade. With globalization, the rate of exotic incursions is growing rapidly. Pathogen changes in one region can quickly result in serious impacts in other distant regions. Surveillance and early detection of new emerging crop pathogen threats coupled to effective control is increasingly critical. However, the great challenge is that these efforts must be undertaken in a coordinated manner across large geographic regions. The detection of a new, highly virulent race of wheat stem rust in Uganda in 1998/99 (Ug99) caused alarm bells to ring throughout the global wheat community. Wind-borne stem rust is the most destructive disease of wheat – which provides 20 percent of calories and protein consumed globally – but largely through resistance breeding it had been effectively controlled worldwide for over three decades. With the detection of Ug99 a very large proportion of the world’s wheat crop was once again vulnerable to a killer disease. One response to the threat of Ug99 was the creation of a surveillance and monitoring system unprecedented in scope or scale. Over the last decade an operational surveillance network, including the online “Rust Tracker,” has been developed, covering all the major wheat growing countries in Africa, Middle East and South Asia. Participation of a large number of multi-disciplinary partners under the umbrella of the Borlaug Global Rust Initiative has been critical for gains made against the disease to date. Progress, key components and enabling factors for success of the wheat rust surveillance system are outlined. Increasingly, advanced technologies are being deployed in efforts to fine tune early warning and forecasting. Successful lessons learned with wheat stem rust are now being applied to other important trans-boundary diseases. A similar surveillance system is now being developed for a new and dangerous maize viral disease that is spreading in East Africa. Maize Lethal Necrosis (MLN) was first detected in Kenya in 2001 and has already spread to five neighbouring countries. Given the large-scale vulnerability of the African maize crop, an effective surveillance and early warning system is urgently needed. The existing wheat rust surveillance system will permit fast-tracking of an operational surveillance system for MLN.