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United States Department of Agriculture

Agricultural Research Service

Title: Incorporation of Distance-of-Spread Calculations into a Weather-Based Model Describing Disease Distribution after Severe Weather Events

Authors
item Irey, Michael
item Gottwald, Timothy

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2006
Publication Date: July 1, 2006
Citation: Irey, M.S., Gottwald, T.R. 2006. Incorporation of distance-of-spread calculations into a weather-based model describing disease distribution after severe weather events. Phytopathology. 96(6): (Supplement) S152.

Interpretive Summary: In Florida, Asiatic citrus canker (Xanthomonas axonopodis pv. citri, XAC) has a long history of multiple introductions followed by eradication campaigns. The latest eradication campaign began in 1995 and continued through 2005 until regulatory agencies concluded that citrus canker had spread to the point that mandatory eradication efforts were no longer viable due to a dramatic increase in disease incidence after several hurricanes crossed the state. Although many mechanisms, including natural events and those involving human actions are involved in the spread of XAC, those involving severe weather were thought to be the major factors that led to the great increase in incidence and geographic range of XAC observed in Florida during 2004 and 2005. Previous research led to the development of weather-based models to predict the direction of spread of XAC; however these models were directional only and did not have a distance component associated with the predictions. A new model has been developed that not only accounts for direction but also predicts the potential distance that XAC can be spread. This new model will be useful for future XAC control efforts.

Technical Abstract: In Florida, Asiatic citrus canker (Xanthomonas axonopodis pv. citri, XAC) has a long history of multiple introductions followed by eradication campaigns. The latest eradication campaign began in 1995 and continued through 2005 until regulatory agencies concluded that citrus canker had spread to the point that mandatory eradication efforts were no longer viable due to a dramatic increase in disease incidence after several hurricanes crossed the state. Although many mechanisms, including natural events and those involving human actions are involved in the spread of XAC, those involving severe weather were thought to be the major factors that led to the great increase in incidence and geographic range of XAC observed in Florida during 2004 and 2005. Previous research led to the development of weather-based models using “wind-rain indexes” to predict the direction of spread of XAC; however these models were directional only and did not have a distance component associated with the predictions. Subsequent analyses have shown that accumulated wind-rain indexes for a given compass direction are strongly correlated with the distance of spread of XAC from a focal point of infection. These calculations have been incorporated into the weather-based predictive model to provide both directional and distance-of -spread predictions for use in future XAC control efforts.

Last Modified: 11/27/2014
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