Interactions between temperature and wheat head wetting duration on fusarium head blight intensity

Abstract

ABSTRACT In experiments conducted in growth chambers with the susceptible wheat cultivar BR 23, interactions between five temperatures (10, 15, 20, 25 and 30°C) and eleven wetting periods were assessed for fusarium head blight (FHB) intensity. Each temperature consisted of one experiment and the wetting hours corresponded to the treatments. The disease occurred even at 10ºC, the minimum tested temperature, and the maximum incidence was at 25oC, both after 50h wetting. Variations in wheat FHB intensity with temperature were explained by the Beta generalized model, and spike wetting duration by the Gompertz model. Disease intensity was modeled according to temperature and wetness duration. The resulting equation represents a description of the response of FHB spikelet incidence to the combined effects of temperature and wetness duration. Since the infection requires a long wetness period, its origin may not be dew but rain, which suggests fungicide application before the occurrence of predicted rain during the wheat predisposition period.