Abstract: Based on the data of the spike rate of wheat scab, winter wheat phenology, and the daily weather data observed in 13 cities of Jiangsu Province, as well as in Tongzhou District (Nantong City) and Jianhu and Funing counties (Yancheng City), a comprehensive impact index and classification indicators for wheat scab were established by statistical methods, including grey correlation, synthetic analysis, census and percentile analysis. The proposed index and indicators were calibrated and validated using empirical data. Then, they were used to analyze the temporal and spatial patterns of wheat scab in Jiangsu Province. Cumulative rainy days, average relative humidity, and average temperature were key meteorological factors affecting wheat scab. Their weights were 0.348, 0.340, and 0.312, respectively. The proposed comprehensive impact index on the basis of these meteorological variables could indicate the situation of wheat scab occurrence in Jiangsu. The classification indicators according to the comprehensive impact index could retrieve the spatiotemporal variations of wheat scab. In recent 16 years from 2002 to 2017, the occurrence of wheat scab in Jiangsu decreased from south to north. However, areas with the most serious wheat scab shifted. The occurrence probability of serious wheat scab in the eastern coastal areas between the Yangtze and Huaihe rivers (mainly in Yancheng City) was significantly higher than that in other areas. Since 2010, serious wheat scab broke out more frequently in Jiangsu, probably due to climate warming. Our results can be used for the prediction and impact assessment of wheat scab, providing guidance for the effective prevention and control of the disease.

Key words: sugarcane-soybean intercropping, reduced nitrogen rate, nitrogen balance, ammonia volatilization, nitrogen leaching.