A climatic risk analysis of the threat posed by the South American leaf blight (SALB) pathogen Microcyclus ulei to major rubber producing countries

South American leaf blight (SALB) of the Pará rubber tree, Hevea brasiliensis Muell. Arg., caused by the plant pathogenic fungus Microcyclus ulei (Henn.) Arx, is recognized as the most serious threat to the natural-rubber industry worldwide. While the pathogen is currently restricted to South America, the warm humid climatic conditions in Asia and Africa, which contribute to over 97 % of world’s natural rubber production are similar to the South American tropics, indicating a significant threat to global rubber production, should the pathogen be introduced to these regions. The present study aims to assess climate suitability for the occurrence of M. ulei in different parts of the world, based on the available literature for M. ulei pathogen establishment, including temperature, relative humidity and precipitation. The risk analysis study provides a preliminary indication of the likely threat of M. ulei in different rubber growing areas of the world and highlights the need for more information on pathogen biology, diversity and environmental tolerance.