CLIMEX and DYMEX simulations of the potential occurrence of rice blast disease in south-eastern Australia.

Rice blast, caused by Magnaporthe grisea does not occur in Australia. The potential for infection and sporulation events by M. grisea under Australian conditions was investigated using two software programs, DYMEX and CLIMEX. The climate of Deniliquin, NSW, representative of the southern Australian rice-growing areas, was projected to the rest of the world and compared, using CLIMEX, with foreign regions where rice blast occurs. Most of the locations whose climates matched that of Deniliquin were within the distribution range of rice blast and the potential for establishment of the disease therefore appears high. A model was also developed and run under DYMEX to predict the potential number of infection and sporulation events of the pathogen. The model was run for the period 1988'1999 with the meteorological data of four representative locations in the Australian ricegrowing region. Out of a possible 11 rice-growing seasons, the number of years favourable for M. grisea ranged from two at Griffith to nine at Yanco. The rice blast model confirmed the CLIMEX results and highlighted the potential threat of rice blast to the Australian rice industry. This paper reports the first disease model developed using DYMEX.