In vitro evaluation of organic and biological products for the control of foliar pathogens associated with barley (Hordeum vulgare)

Background/Objective. Brown spot, net blotch, and Fusarium head blight are significant emerging diseases in barley (Hordeum vulgare), and extracts derived from plants and biological organisms offer alternatives for their control. The aim of this study was to evaluate, in vitro, the effectiveness of commercial organic and biological products for the control of three fungi associated with diseases in barley. Experimental development. The experiment was established in 2023 at the INIFAPCEVAMEX phytopathology laboratory, using a completely randomized experimental design with four replicates. The experimental unit consisted of a Petri dish containing PDA medium amended with the product under evaluation, along with a control for each fungus. Isolates of Bipolaris sorokiniana, Drechslera teres, and Fusarium graminearum were used to evaluate eight commercial organic products and three biological products, employing the poisoned-medium technique. The diameter (mm) of mycelial growth (MG) was measured, and the percentage of inhibition of the mycelial growth (PIMG) was calculated. Data were subjected to analysis of variance and mean comparisons (Tukey’s test, p≤0.05). Results. The products (active ingredient) with a mycelial growth (GM) of less than 5 mm were for B. sorokiniana: Bacillus amyloliquefaciens, cinnamon extract, a mixture of argemone + berberine + ricin + α-terthienyl, and gobernadora (Larrea tridentata) extract; B. amyloliquefaciens for D. teres; and cinnamon extract, B. amyloliquefaciens, and corn vegetable oil for F. graminearum. The largest GM values were observed with neem oil extract for B. sorokiniana (63.75 mm) and D. teres (85 mm), and with garlic extract for F. graminearum (82.25 mm). In terms of the percentage of inhibition of mycelial growth (PIMG), the organic products showed outstanding results: B. amyloliquefaciens (100, 100, 95.5%) and cinnamon extract (100, 80.75, 97%) for B. sorokiniana, D. teres, and F. graminearum, respectively. Conclusion. The products that demonstrated outstanding efficacy based on the PIMG method were B. amyloliquefaciens (100%) and cinnamon extract (100%) against B. sorokiniana; B. amyloliquefaciens (100%) and Trichoderma Sub (83.50%) against D. teres; and, for F. graminearum, cinnamon extract (97%) and B. amyloliquefaciens (95.50%). Field trials are necessary to determine their in vivo effectiveness.