Leveraging of mycogenic copper oxide nanostructures for disease management of Alternaria blight of Brassica juncea

Brassica is one of the crops sensitive to low copper supply, leading to Alternaria blight. The present study reflects the synthesis of myco-derived copper oxide (M-CuO) nanoparticles (NPs) from Trichoderma asperellum and investigates their effect against Alternaria blight of Brassica in two soil types, alluvial and calcareous. Foliar applications of different treatments were used to treat plants: T1 (mancozeb@0.2%), T2 (propiconazole@0.05%), T3 (T. asperellum filtrate), T4 (M-CuO NPs), T5 chemically synthesized (C-CuO NPs), and T6 bulk phase (BP-CuO @25, 50, 100, 150, and 200 ppm) of each in twice such as protectant and curative method under pot experiments. M-CuO NPs in two protective sprays exhibit up to 75% disease suppression in alluvial soil, compared to 68.9% suppression in curative spray at 200 ppm. Maximum seed yield and seed number were obtained, 1.95 g/plant and 850 seeds/plant in alluvial soil, but in calcareous soil, seed yield (1.14 g/plant) and seed number 414 seeds/plant were recorded in plants supplemented with M-CuO NPs as a protectant. In both soils, maximum plant height was increased by protective applications of M-CuO NPs at 200 ppm. Thus, the present study suggested that among foliar sprays of copper nanocompounds, protective activity shows better results as compared to curative activity. Among all the treatments, M-CuO NPs were found to be most effective in suppressing disease and improving productivity and growth-promoting effects of Brassica.