Dwarf Bunt of Wheat in China: Potential Sites from Satellite Studies1

Abstract

AbstractCommon bunts of wheat (Triticumspecies) caused by Tilletia caries(DC.) Tul. and T. foetida(Wall.) Liro are present in China, but dwarf bunt has not been reported. Beginning in 1974, wheat shipments from U.S. Pacific Coast states to the People's Republic of China were stopped because they contained spores of the dwarf bunt fungus (Tilletia controversaKuhn), a pathogen affecting winter wheat. This quarantine against T. controversareflected a major Chinese concern that T. controversahad the potential to cause a widespread dwarf bunt epidemic of wheat in China. Thus, the objective of this study was to determine if agricultural lands in China's winter wheat region possessed an important climatic factor (30‐day persistent snow cover) regularly associated with this disease. Weather satellite based NOAA/NESDIS snow and ice charts were used to locate the snow areas occurring on agricultural lands. The agricultural lands were identified using Landsat multispectral scanner imagery. During the period November 1966 through February 1982, 11 instances of persistent snow cover were identified; these occurred in 7 out of the 16 yrs. One area had snow during only 1 yr, four areas had snow during 2 sequential years, and nine areas had snow cover during more than 1 nonsequential yr. Therefore, in China's major winter wheat region the potential sites for the dwarf bunt disease of wheat were rare in time and space, and it appears exceedingly unlikely that a widespread development of this disease could ever occur in China.