Meteorological-Based Predictions of Wheat Head Blight Epidemic in the Southern Argentinean Pampas Region

Abstract

In Argentina, head blight is a highly risky disease (caused by Fusarium graminearum), although its occurrence is sporadic depending on prevalent environmental variables. These traits stimulated the development of predictive models of head blight occurrence which would help growers in the selection of control strategies. Empirical equations for predicting head blight incidence were developed at Pergamino (33° 56′ S, 60° 30′ W) associating temperature and moisture variables with mean disease data. Recently a new fundamental-empirical approach for estimating Fusarium index (incidence% x severity%/100) was developed using data of Pergamino and Marcos Juarez (32° 41′ S, 62°07′ W). In this study our objective was to validate both approaches at three more southern locations: La Dulce (38° 10′ S, 58° 00′ W), Miramar (38° 00′ S, 57° 33′ W) and Balcarce (37° 45′ S, 58° 18W), for the 2001 crop season. Examining partial and mean deviation values between observed and predicted incidence data, an underestimation especially at La Dulce was assessed. A clear improvement of incidence goodness of fit estimations was obtained decreasing the heat accumulation defining the length of the wheat critical period for infection. Employing this last critical period length for the fundamental-empirical approach led to satisfactory Fusarium index predictions. This study showed that both approaches developed at northern locations of the Pampas region can be portable and useful for predicting disease intensity at more southern locations, making only a few changes.