An international perspective on wheat blast
E. DUVEILLER (1), D. Hodson (2), K. Sonder (1), A. von Tiedemann (3)
(1) CIMMYT, Mexico D.F., MEXICO; (2) Food and Agriculture Organization, Rome, ITALY; (3) Georg-August-University of Göttingen, Göttingen, GERMANY
Phytopathology 101:S220

Wheat blast caused by Magnaporthe grisea has been recorded in Brazil since the mid 1980s and occurs in parts of Bolivia, Paraguay and Argentina. It can account for 10 to 100% crop losses. Control of the disease is limited by lack of effective fungicide spray schemes and resistant varieties. A climate similarity approach was used to estimate the risk of wheat blast in other continents. Climatic similarity was derived from the Worldclim database considering the coolest quarter in which wheat is grown in warmer wheat areas, while similarity comparisons with the areas of cultivation in the northern hemisphere were drawn from the warmest quarter of the year. The preliminary analysis revealed areas of risk in parts of Central India, Bangladesh and Ethiopia. Similarity was also identified with areas in the northern hemisphere, Eurasia and North America. However a study using the Homologue software package showed that northern Eurasia and America did not match a year-round climate comparison with areas in South America where wheat blast occurs. Yet a few areas at the border of wheat growing regions in the Indian sub-continent and parts of Africa show a 40–60% similarity with affected areas in South America underlining that risk of wheat blast pathogen survival exists. From the limited knowledge available the survival of wheat blast pathogen in the cool or cold season is unlikely, diminishing the current risk of wheat blast in the northern hemispheric wheat production zones.

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