Risk Assessment Models for Wheat Fusarium Head Blight Epidemics
Based on Within-Season Weather Data
E. D. De Wolf, L. V. Madden, and P. E. Lipps
First author: Department of Plant Pathology, The Pennsylvania State University, Buckhout Laboratory, University Park 16802; and second
and third authors: Department of Plant Pathology, The Ohio State University/OARDC, 1680 Madison Ave., Wooster 44691.
Accepted for publication 12 November 2002.
De Wolf, E. D., Madden, L. V., and Lipps, P. E. 2003. Risk assessment
models for wheat Fusarium head blight epidemics based on within-
season weather data. Phytopathology 93:428-435.
Logistic regression models for wheat Fusarium head blight were de-
veloped using information collected at 50 location-years, including four
states, representing three different U.S. wheat-production regions. Non-
parametric correlation analysis and stepwise logistic regression analysis
identified combinations of temperature, relative humidity, and rainfall or
durations of specified weather conditions, for 7 days prior to anthesis,
and 10 days beginning at crop anthesis, as potential predictor variables.
Prediction accuracy of developed logistic regression models ranged from
62 to 85%. Models suitable for application as a disease warning system
were identified based on model prediction accuracy, sensitivity, specifi-
city, and availability of weather variables at crop anthesis. Four of the
identified models correctly classified 84% of the 50 location-years. A
fifth model that used only pre-anthesis weather conditions correctly
classified 70% of the location-years. The most useful predictor variables
were the duration (h) of precipitation 7 days prior to anthesis, duration
(h) that temperature was between 15 and 30°C 7 days prior to anthesis,
and the duration (h) that temperature was between 15 and 30°C and
relative humidity was greater than or equal to 90%. When model per-
formance was evaluated with an independent validation set (
prediction accuracy was only 6% lower than the accuracy for the original
data sets. These results indicate that narrow time periods around crop
anthesis can be used to predict Fusarium head blight epidemics.
: disease forecasting,
, head scab.
Epidemics of Fusarium head blight (FHB), caused by
Schwabe), have had a deleterious impact on wheat (
L. em. Thell) production in many regions of North
America. Accounts of severe epidemics of FHB, or scab, were
recorded by pioneering plant pathologists, such as J. C. Arthur (4),
A. D. Selby (26), and others (1,5,25) during the late 1800s and
early 1900s. In recent years, epidemics of FHB have occurred in
many wheat-producing states of the United States, including
North Dakota, Minnesota, South Dakota, Ohio, Indiana, Michi-
gan, Missouri, Kansas, and Arkansas (16). Epidemics of FHB