Temporal and spatial dynamics of wheat powdery mildew in Sichuan Province, China

• A logistic curve best summarized the development of powdery mildew (PM) over a 5-year period.
• Models were developed that can be used to predict PM with an accuracy of 85%.
• PM spread as far as 534 cm from the disease center in one infection cycle.
• The exponential and quadratic functions best described PM dispersal.
• Meteorological factors in March and April were closely correlated with disease development.

Wheat powdery mildew, which is caused by Blumeria graminis f. sp. tritici, is an important and destructive wheat disease that can cause a considerable reduction in grain yield. The temporal dynamics of wheat powdery mildew examined over a five-year period (2007–2012) indicated that disease incidence and index fitted an “S”-shaped curve. The initial stage of wheat powdery mildew occurred mainly in late November, and the logistic stage in 2010–2011 was the longest in all experiments. The 2010 and 2011 experiments exhibited the highest disease index across the five years. The logistic curve best fit disease development during the five years and provided a good prediction of powdery mildew with an accuracy of 85%. Meteorological factors in March and April were highly correlated with disease index. To better understand powdery mildew epidemics, effective dispersal of the fungus was studied in 2011 and 2012. The results showed that the pathogen can spread more than 500 cm in one infection cycle. The rate of disease spread was relatively fast between late March and mid-April in 2012 and reached 175 cm/d. Curve fitting of the disease spread distance in eight directions identified the exponential and quadratic functions as the best fitting curves. Information on the temporal dynamics and effective spread distance of wheat powdery mildew and the relationship between disease epidemics and weather conditions provides the insight needed for future disease forecasting and management.