Efficacy of botanicals and bioagents against root rot of cowpea incited by Rhizoctonia bataticola

Cowpea [Vigna unguiculata (L.) Walp], an annual legume, is subject to root rot, a major disease incited by the fungus Rhizoctonia bataticola (Macrophomina phaseolina). This infection leads to leaf yellowing, rapid defoliation, wilting, and necrosis, as the pathogen blocks the plant’s vascular bundles and secretes toxins. Infected stems and leaves become dry, brittle, and straw-colored. An experiment to address this disease was conducted at the farm of SKNCOA, Jobner, during Kharif 2023. Cowpea root rot, a major disease, leads to symptoms like leaf yellowing, rapid defoliation, wilting, necrosis, and dry, brittle stems/leaves due to vascular blockage. An experiment conducted in Kharif 2023 at SKNCOA, Jobner to tested the management strategies against this pathogen. Six botanicals were tested at 5, 10, and 15% concentrations by the poisoned food technique, among these garlic (86.43, 93.96 and 97.16%), was found most effective in inhibiting mycelial growth, followed by neem (84.76, 90.40 and 94.93%) leaves extract. Similarly, under field conditions using seed treatment, garlic (28.03%) was the most effective botanical, followed by neem (34.56%). Among four bioagents tested via the dual culture technique, Trichoderma harzianum (79.87%) was the most effective in inhibiting mycelial growth, followed by Trichoderma viride (71.75%). Field application as a seed treatment confirmed these results, with Trichoderma harzianum (26.46%) being the most effective bioagent against the root rot pathogen, followed by Trichoderma viride (33.80%).