In-vitro and in-vivo evaluation of different plant-based by-products against Meloidogyne incognita and Sclerotinia sclerotiorum in French bean

Abstract

The present study includes in-vitro evaluation of plant-based products against Meloidogyne incognita and Sclerotinia sclerotiorum under and further integration of the promising treatments with Trichoderma harzianum and fungicide, Carbendazim 50WP, to manage the nematode and fungal disease complex in French bean. During in-vitro studies, for root knot nematode, M. incognita, four doses, i.e., 2.5, 5.0, 10.0 and 15.0% suspension of each plant-based by-products viz., neem cake, mustard cake, garlic extract, and neem leaf extract was tested. In comparison, for S. sclerotiorum three doses, 5.0%, 10.0%, 15.0% suspension of each plant-based by-product was tested. Maximum egg hatch inhibition was observed in neem leaf extract at 15.0% concentration with 83.65% inhibition over the untreated control after 72 hours, followed by mustard cake at 15% after 72 hours (82.52%). Further, maximum juvenile mortality was recorded in mustard cake 15% recording 90.0% mortality, followed by neem cake 15% with 89.67% mortality over control after 72 hours. The LC50 of neem leaf extract for egg hatch inhibition was 743.32 ppm, while for mustard cake it was 854.38 ppm after 72 hours. While for juvenile mortality mustard cake showed LC50 at the concentration of 343.22 ppm after 72 hours. For S. sclerotiorum, maximum percent mycelial inhibition was recorded in neem leaf extract with 70.0% inhibition at 15.0% concentration over control, followed by neem cake with 69.89% inhibition at 15.0%. Among the total 12 treatments tested under in-vivo conditions, the results revealed soil application of mustard cake 2.5 g/kg soil before sowing +foliar spray of carbendazim 50 WP (0.25%) gave maximum reduction in sclerotinia rot disease (58.55%) along with 36.70% reduction in root knot nematode infestation while soil application of MC 2.5 g/kg soil before sowing + T. harzianum 20 g/kg soil 15 DAS recorded minimum root nematode infestation along with 50.97% reduction in sclerotinia rot disease. The results indicate that integration of soil amendments with bio-agent or fungicide can be utilised to develop cost-effective safer alternative to manage root knot nematode and sclerotinia rot disease complex in French bean.