Tracking plant pathogens is a vital part of agro-economic development, says Maurizio Vurro.
As with human and animal diseases, the emergence or re-emergence of plant diseases is often due to man’s activities – a consequence of mass tourism, global trade, or changes to farming practises or the environment.
Although our ability to diagnose and control diseases is greater than in the past, emerging infectious diseases (EIDs) are still able to cause tremendous crop losses. In developing countries in particular, the economic and social impact is often underestimated as I, with colleagues, recently discussed in the journal Food Security.
Cassava Mosaic Virus Disease, for example, is capable of reducing yields by 80-90% and suspends cassava cultivation in many areas of East Africa. Striga hermonthica, a parasitic weed, affects cereal cultivation across at least 5 million hectares in sub-Saharan Africa. And the rust fungus Ug99, which has overcome resistant varieties, has spread from Uganda and threatens most of the wheat-growing countries in the world.
Countries with limited resources are threatened when pandemics occur on important food crops, such as Xanthomonas Banana Wilt, a bacterial disease that affects the food security of 70M people in Uganda. This kind of low crop productivity contributes directly to malnutrition, and indirectly to the spread of human diseases and the collapse of the environment because poor rural areas are abandoned with a concomitant phenomenon of urban overcrowding.
In developing countries there are clear links between food insecurity and institutional fragility. The 2008 food crisis highlighted the acute vulnerability of net food-importing developing countries in the sub-Saharan Africa. In the past two decades, those countries have reduced investment in rural areas, exacerbating migration to cities and increasing the demand for food imports. This vicious circle further undermines the capacity of agriculture to produce the required food and increases dependence on food imports.
Hunger is further worsened by the lack of public interventions, institutional fragility, limited public investments in rural areas, political and administrative chaos, war and local guerrilla action, and climate change. In this context, the effectiveness of humanitarian aid, in the absence of appropriate conditions to start productive activities, is largely frustrated.
Surveillance of EIDs is thus crucial for developing countries’ agricultural self-sufficiency and wider social economy, but these technologies are often expensive and require technical preparation, economic investment and personnel. Given the cost, many developing countries have limited control systems; nor can they acquire and update lists of emerging pathogens within their borders.
The consequence is that many diseases in developing countries simply spread without being recognized and monitored.
In Western countries surveillance systems are easier to deploy because of existing community networks, there are more economic opportunities, and greater availability of the necessary technologies at affordable prices. Furthermore, in developed countries there are social safety nets to support those most affected; food reserves that limit the risk of famine; research systems and technical support services that enable management of those diseases or diversification to alternative crops; and warning systems that allow the prompt application of control measures.
Similar systems must be urgently established in developing countries to avert the socio-economic disasters that can be caused by plant diseases. The development of a large EID-monitoring organization on a territorial basis, with clear roles and accountabilities, is of utmost importance.
About Maurizio Vurro
Maurizio Vurro has been a senior researcher at the Institute of Sciences of Food Production, National Research Council, since 2001. His main scientific interests are the use of microbes and natural metabolites in biological control, in particular against weeds. He recently led the project ‘Enhancement and exploitation of soil-biocontrol agents for bio-constraint management in crops’ within the 6th EU Framework Programme and is the author of more than 70 articles in scientific journals, three books, and seven book chapters.