Preventive and curative control of sclerotium rot disease of cocoyam cormel (Colocasia esculenta [L., Scott]) using plant extracts and Trichoderma koningii

Abstract

Aqueous leaf extracts from air-dried samples of Carica papaya, Chromolaena odorata, and Azadirachta indica were screened for antifungal properties against Sclerotium rolfsii at 50, 70, and 100% concentrations and Trichoderma koningii (4.9 × 10 6 spores/ml) in vivo. Dithane M45 at 2% concentration was used as positive control for better comparison. The aqueous extracts and T. koningii were applied as preventive and curative methods by spraying fresh and healthy cormels with S. rolfsii (3.75 × 10 5 spores/ml). The results showed that Mancozeb and T. koningii had significant effect (preventive and curative) on disease severity and percentage weight loss. Furthermore, preventive and curative application of T. koningii significantly reduced disease severity. C. papaya at 50% concentration (preventive method) had the highest disease severity (3.8%), as to the control (4.0%). The extracts and dithane M45 were more effective as curative, while T. koningii was better as preventive method. The result on percentage weight loss showed that C. odorata (70% concentration) had the highest (49.61%), followed by C. papaya (50%) with 47.85%, and the least was A. indica (23.77%) at 70%. C. odorata and A. indica 50% and 100% concentrations, respectively, significantly reduced weight loss, while C. odorata (100% concentration) and the control gave the highest percentage weight loss in the curative method. Conclusively, plant extracts and T. koningii were more effective in controlling the disease and reduction in weight loss than mancozeb.

Biocidal potential of Three Plant Extracts on Rhizopus stolonifer, Causal Organism of Irish Potato (Solanum tuberosum L.) Tuber Rot

“…This result indicates that the extracts of the test plants could effectively reduce rot development in Irish potato tubers at test concentrations. The ability of plant extracts to reduce rot in tuber crops have been reported by earlier researchers (Nwachukwu and Osuji, 2008;Strivastava andKshma, 2014: Boungab et al 2015;Nwauzoma et. al., 2017).…”

“…Similar results on the reduction of weight loss using ashes from the bark of kola nut tree, neem tree, and inflorescence of oil palm have been reported (Eze, 1991). In a related study, Nwauzoma et al (2017) reported that leaf extracts of Carica papaya, Chromolaena odorata and Azadirachta indica significantly reduced rot in Sclerotium rolfsii inoculated tubers after 14 days in storage.…”

“…This was carried out according to the methods of Nwauzoma et al, (2017). About three 5mm mycelia disk of the pathogen (R. stolonifer) from a 4 days old pure culture was grown for 14days in a PDA broth containing 1g of PDA mixed in 200 ml sterile distilled water.…”