PREDICTION OF POTENTIAL EPIDEMIOLOGICAL AREAS IN CHINA PRONE TO KARNAL BUNT OF WHEAT
Z. Wei-chuan, Z. Gui-ming
Tilletia indica Mitra, the cause of Karnal bunt of wheat, is an important quarantine disease around the world. The Humid Thermal Index (HTI) model, and the bioclimate zoning map of wheat in China are based on critical values of key climatic factors during the susceptible period (heading and anthesis of wheat). We have calculated improvements to the HTI value for both early and late sown wheat varieties, with 21 days as a cycle (heading and anthesis period) and 1 day as a slip statistical unit. A GeoPhytopathology Model (GPMTI) for T. indica was built using a Microsoft Access Database, Map- Info MapX and Visual Basic, and was used to predict the potential geographic distribution areas of T. indica using climate data collected in the past 30 years from 670 meteorological stations. The results showed that the pathogen could establish itself in 60% of sites in China (nearly 4,580,000 km2), and this region can be divided into four areas: safe areas (HTI value for all periods unsuitable for disease development), low risk areas (HTI value for less than one-third of the periods suitable for disease development), risk areas (HTI value for between one-third and two-thirds of the periods suitable for disease development) and high risk areas (HTI value for more than two-thirds of the periods suitable for disease development). The risk areas and high risk areas were about 3,210,000 km2.