Progression of wheat Tan spot under different bioclimatic stages and agricultural practices

Tan spot, caused by Pyrenophora tritici-repentis, is a severe worldwide wheat foliar disease and has become common in Tunisia. Two hundred wheat field surveys were conducted in northern Tunisia during the 2017-2019 seasons to determine disease intensity and the correlation of the tan spot with agricultural practices and environmental factors. The disease infested 67% of the visited regions. The highest prevalence (87.5%), incidence (> 30%), and severity (> 10%) were observed in sub-humid regions, contrary to the middle semi-arid regions. Logistic regression was used to analyse the correlation of incidence and severity with various factors as independent variables. In a multiple variable model, the bioclimatic stages, variety, previous crop, humidity, and rainfall were significantly associated with tan spot incidence and severity. High incidence and severity were significantly correlated to the sub-humid regions, varieties Maâli, Razzak, Karim, and Carioca, rainfall, high level of humidity, and monoculture. The correlation between the tan spot and several environmental factors must be considered to ensure successful and sustainable disease management strategies.