Climatic mapping to identify high-risk areas for Cylindrocladium quinqueseptatum leaf blight on eucalypts in mainland South East Asia and around the world

Cylindrocladium quinqueseptatum is a pathogen on a wide range of hosts. It affects at least 20 species of eucalypts and is an important causal agent o f leaf blight of Eucalyptus camaldulensis in central and southern Vietnam. Results from previous studies and observations of broadscale infection patt erns in mainland South East Asia were used to derive simple rules (i.e. mea n minimum temperature of coldest month greater than or equal to 16 degrees C and mean annual precipitation greater than or equal to 1400 mm) to identi fy locations which are likely to have a high risk of C. quinqueseptatum lea f blight (CqLB). Climatic mapping programs, which include interpolated clim atic data estimated for numerous locations, were used to map these high ris k areas in Africa, Australia and Latin America as well as in South East Asi a. The predicted high-risk areas included several regions where CqLB has al ready been reported and the maps generated suggested other areas which may be at risk under present climatic conditions given the presence of C. quinq ueseptatum and susceptible hosts. Some simple climate change scenarios were also used to suggest areas in mainland South East Asia which may become vu lnerable to CqLB over the next 50 years. It is concluded that climatic mapp ing programs can assist the broadscale evaluation of risk of CqLB infection s, although it is recognised that more detailed models and survey informati on are also needed. (C) 2000 Elsevier Science Ltd. All rights reserved.