Evaluación de fungicidas curasemillas para el control de Pyrenophora teres f. teres en cebada

Net blotch (NB), caused by Pyrenophora teres f. teres, represents a significant threat to barley production. Chemical seed treatment emerges as a key preventive strategy to limit its introduction and spread in crops. To evaluate the efficacy of five seed treatment fungicides in controlling NB during the initial stages of barley development, a field experiment was conducted using a randomized complete block design with four replicates. The cultivar Explorer, which has high to intermediate susceptibility, was used with an initial fungal load of 5%. The treatments consisted of the following active ingredient formulations for seed treatment: metalaxyl, penflufen, prothioconazole; fluxapiroxad + triticonazole; difenoconazole + fludioxonil + sedaxane + thiamethoxam; carbendazim + iprodione + thiram; azoxystrobin + iprodione + metalaxyl + triticonazole, along with an untreated control. The evaluated variables were percentage of plant emergence and disease incidence at 13 days post-emergence (DPE, growth stage Z1.3), and disease severity at 31 (Z2.2), 50 (Z3.0), and 73 DPE (Z4.3). From these, the area under the disease progress curve (AUDPC) and the percentage of control efficacy (%CE) were calculated. Weather conditions during the trial were highly conducive to MRtr development. No significant differences were observed among treatments for plant emergence or early disease incidence (13 DPE). At Z2.2, disease severity was high—approaching the critical threshold—but no significant differences were detected between treatments. However, significant differences emerged at Z3.0, where the mixtures containing fluxapiroxad + triticonazole and sedaxane + fludioxonil + difenoconazole + thiamethoxam exhibited the lowest severity levels. AUDPC analysis confirmed that these two combinations were the most effective in limiting NB progression, thus providing the best relative control under the specific trial conditions. However, the %CE of these treatments was to low, <50%, highlighting that under conditions of high inoculum pressure and favorable weather, seed treatment alone was insufficient to maintain disease levels below critical thresholds. This underscores the importance of integrating seed treatments with additional disease management strategies, emphasizing continuous monitoring and the responsible use of fungicides within an integrated disease management framework.