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Nerine peach. © INRA, MONET René

Pathogen-related harvest losses: analysis and quantification

Wheat: analysis of pathogenic risks in the future

If account is taken of future changes to the environment and cultivation practices, will wheat be more or less threatened by its pathogens? An international network is analysing the risks of pathogen attack in three main types of agrosystem.

Updated on 09/12/2016
Published on 01/12/2016

Harvesting wheat in the Himalayan hills of Nepal.  The ears are harvested manually by pinching the stems between two wooden sticks and then pulling upwards.. © INRA, BONNEMAIRE Joseph
Harvesting wheat in the Himalayan hills of Nepal. The ears are harvested manually by pinching the stems between two wooden sticks and then pulling upwards. © INRA, BONNEMAIRE Joseph

Wheat under threat from pathogens

Wheat, the cereal crop that covers the largest area of cultivated land in the world, is under major threat from several groups of pathogenic agents.  Since January 2013, members of the RAW (Risk Analysis in Wheat) network have been analysing data on wheat pests and harvest losses, and modelling the future evolution of the risks faced by crop.  An explanation from Serge Savary in the Joint Research Unit for Agroecology, Innovations and Territories (AGIR) in Toulouse, and coordinator of the network: “The first stage in this work consisted in defining the current characteristics of wheat-based agrosystems and the different profiles of the pests concerned.  The analysis of risks to harvests and of factors for change (climate, agricultural practices, varietal resistance, etc.) will then allow us to make projections for the future.”

Wheat yield growth rates in 2010 (tonnes per hectare and per year). © INRA
Wheat yield growth rates in 2010 (tonnes per hectare and per year) © INRA

Perspectives at the 2050 horizon for six groups of pathogens

The study made a distinction between three types of agrosystem:

  • Type 1: small intensive farms in a temperate climate (Western Europe, Eastern USA, North-east China);
  • Type 2: large farms in a continental climate (American Midwest, Canada, Brazil);
  • Type 3: semi-arid or transition climate (Central Asia, India, Middle East, North Africa).

Evolutionary trends at the horizon of 2050 for these three agrosystems were predicted as a function of modifications to farming practices and global changes.  For example, the climate is expected to become less favourable for agrosystem 1. The effects of these same factors were evaluated with respect to the six functional groups of wheat pathogens: wheat rust fungi, fusarium head blight, glume blotch and stripe disease (pathogens of the roots and stem bases) and insect-borne viruses.

 Evolution of risks in the three agrosystems

Based on these scenarios, the long-term risks of epidemics and wheat harvest losses were envisaged for the six groups of pathogens in the three agrosystems.

  • For type 1, the probabilities of occurrence of the different groups of disease do not evolve, but the degree of risk relative to fusarium is higher, while that concerning rusts and glume blotch is lower.
  • By contrast, for type 2, the probabilities increase but the degree is unchanged, except in the case of rusts (for which the probability remains stable but the degree of risk increases).
  • For type 3, the probabilities of fusarium and rusts increase, as does the degree of risk of glume blotch and stripe disease.

Based on the concept of the functional group of pathogens as an elemental unit for foresight, the RAW network has underlined the importance of the links between the agrosystem, site of production and wheat health.  “We need to understand plant health in all its dimensions” concludes Serge Savary.

Scientific contact(s):

Associated Division(s):
Science for Action and Development, Environment and Agronomy
Associated Centre(s):

The RAW network

RAW (Risk Analysis in Wheat) is a prospective analytical network on risks in wheat.  Driven by INRA, it includes partners from Europe, Asia and America.

Partners: Italy: V. Rossi (U. Cattolica del Sacro Cuore, Piacenza); Brazil: E. Del Ponte (U. Federal do Rio Grande do Sul), M. Fernandes (EMBRAPA); Costa Rica: P. D. Esker (U. de C.-R.); Sweden: A. Djurle, J. Yuen (SLU-Uppsala); Norway: A. Ficke (Bioforsk); India: J. Kumar (G.B. Pant University, Pantnagar), USA: L.V. Madden, P. Paul (Ohio State University), N. McRoberts (UC Davis); Mexico: P. Singh, CIMMYT (International Maize and Wheat Improvement Center).