Efficacy of fungicides to control lentil blight disease caused by Stemphyilium beticola and Alternaria alternata in Iran through multi-locational field trials, in-vitro and glasshouse studies

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Lentil is the second most important pulse crop in Iran’s rainfed and dryland areas. In 2015, a severe blight disease was observed on the crop in the main lentil-producing regions of the country, leading to complete defoliation and a yield loss of over 80%. Studies using morphological and molecular approaches identified the disease agents as Stemphylium beticola and Alternaria alternata. To determine appropriate fungicides, a research study was conducted from 2018 to 2021 in the field conditions of Moghan and Gachsaran provinces located in the hot spots of the North-West and South-West of the country, respectively. Five fungicides were tested in two concentrations each, including Iprodione + Carbendazim 52.5% WP at 0.75 and 1.0 kg/ha, Propiconazole 25% EC at 0.75 and 1.0 L/ha, Signum 33.4% WG at 0.75 and 1.0 g/ha, Mancozeb 80% WP at 1.0 and 1.5 kg/ha and Chlorothalonil 75% WP at 1.5 and 2.0 kg/ha. The experiment was also repeated in the glasshouse with the same concentrations and in vitro using agar-dilution method with 0, 10, 20, 40, and 60 ppm of fungicidal concentrations. Results showed that Signum® was the most effective chemical compound for disease control. However, based on economic analysis, Mancozeb and Chlorothalonil at a concentration of 1.5 kg/ha are recommended for disease control in the hot spots, respectively.