Programa de cebada, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias-Campo Experimental Valle de , Coatlinchán, Texcoco, Estado de México, Mexico
In Mexico, the production of barley (Hordeum vulgare L.) is affected by various diseases including leaf rust (LR) caused by Puccinia hordei Otth. In the spring-summer/2018 cycle, under rainfed conditions and natural incidence of HR, a factorial test was established under a randomized complete block design, in the municipalities of Texcoco and Temascalapa, State of Mexico and Tlaxco, Tlaxcala, to evaluate the effect of two fungicides (Azoxistrobin 11.1% + Tebuconazole 18.4% and Tebuconazole 25%) on the LR control in six varieties of barley. The variables measured were day to heading and maturity (DE, DM), Plant height (PH), Test weight (TW), grain yield (Yield) and final severity of the disease (FDS). Highly significant differences were found for TW, Yield and FDS for varieties, fungicides and localities (Tukey, p≤ 0.05). The most effective fungicide was Azoxistrobin 11.1% + Tebuconazole 18.4% taking FDS of 2% and yield (REND) of 2,757.2 kg ha-1 compared to the non-fungicide check which had 23% FDS and yield of 2,262.7 kg ha-1. The variety with the greatest resistance was ABI Voyager (10MS) and the most susceptible, Doña Josefa (40S). Disease control influenced performance, there were losses of 31% in Apizaco; 20% in Esmeralda; 19% for Doña Josefa and ABI Voyager; Maravilla with 16% and AC Metcalfe 9%. Resistance levels observed together with the use of fungicides will allow a comprehensive control of the disease.