Ashish Ghimire, Ashish Ghimire, Hemant Joshi, Alisha Ghimire, Alisha Ghimire, Sushil Regmi, Bidhan Hamal Thakuri, Jhalak Bahadur Mauni, Sushil Chaudhary, Bhawana Kumari Bogati, Tapta Raj Jaishi, Krishna Raj Pandey
Rhizoctonia solani Kühn is a major cause of damping off in vegetable seedlings, a serious problem for vegetable growers in Nepal. This study employed in vitro and in planta assays to evaluate the concentration-dependent efficacy of chemical fungicides and the potential of botanical extracts as eco-friendly alternatives for sustainable management of damping-off disease of crucifers, providing context-specific evidence on disease management under local conditions. Nine chemical fungicides and ten botanical extracts were tested under a completely randomized design using the poisoned food technique, whereas the most effective treatments were further assessed in planta. All fungicides significantly inhibited mycelial growth at 3 days after incubation. Systemic fungicides, particularly the demethylation inhibitors, were statistically superior across all tested concentrations, with hexaconazole performing strongly across all concentrations. Chlorothalonil (500 and 750 ppm) and mancozeb (750 ppm) were the most effective non-systemic fungicides with > 70% inhibition. Among botanical extracts, garlic exhibited the strongest antifungal activity (> 52% inhibition), followed by jimsonweed (10 and 15%) and turmeric (15%). Under the in planta assay, chlorothalonil provided complete control at 500 ppm and 750 ppm, and only around 7% disease incidence at 250 ppm. Propiconazole and hexaconazole (all doses), along with propineb and mancozeb (500 and 750 ppm), also maintained incidence below 30%. Consistent with in vitro results, garlic (10 and 15%) and jimsonweed (15%) extracts reduced disease incidence to below 35%. The findings show that systemic fungicides effectively reduced damping-off disease, while botanicals such as garlic and jimsonweed demonstrated promising antifungal activity. Future research should explore potential synergistic effects between effective botanical extracts and reduced doses of systemic fungicides to support the development of more sustainable disease management strategies.