Evaluation of efficacy of false yam (Icacina oliviformis) as surface protectant against rot pathogens of white yam (Dioscora rotundata Poir)

Rots in yam tubers are the dominant cause of postharvest losses. Therefore, studies were con­ducted to identify the rot-causing organisms in yam and to evaluate the efficacy of false yam (Icacina oliviformis) plant extracts as surface protectants in the storage of yam. The experiment was laid out in a completely randomized design (CRD) design with five treatments (fruit, root and leaf extract of false yam, Mancozeb and tap water) replicated three times. Two concen­trations (50% and 100%) of each extract were also tested. Species were identified based on the structural features, the characteristics and properties of the spore and mycelium. A spore suspension of yam rot fungi was sprayed on healthy yam tubers that had been pretreated with the extracts. Results showed that fungi isolated from rotted yams were Aspergillus niger, A. fla­vus and Penicillium sclerotigenum. Leaf extracts (both 50% and 100%) had the highest growth inhibitions on all the three fungi isolated in vitro. Tubers treated with root and leaf extracts of false yam had a decreased tuber rot lengths of 1.80 mm2 and 2.17 mm2, respectively. The leaves and roots of false yam can be used as a surface protectant of yam in place of Mancozeb. Keywords: Icacina oliviformis; Dioscora rotundata; Mancozeb; Pathogenicity; Aspergillus spp

Variations in the level of resistance to root-knot nematodes (Meloidogyne spp.) infestation among ten cowpeas (Vigna unguiculata L. Walp.) genotypes

The cultivation of cowpea (Vigna unguiculata L. Walp.) cultivars that are tolerant to root-knot nematode attack is among the environmentally safe approach to managing the root-knot nematode menace in cultivated crops. In this study, the tolerance of 10 cowpea genotypes to root-knot nematodes infestation was evaluated in a pot experiment conducted in a Screenhouse, at the University for Development Studies, Nyankpala Campus. The experiment was laid out in a completely randomized design with three replications. The number of second stage juveniles (J2) per 250 cm3 of soil sample were counted while the severity of root-knot nematode damage (root galls) was assessed. The reproduction index (RI) was used to classify the varieties as resistant or susceptible. There was a significant difference (P < 0.05) in the number of second stage juveniles of root-knot nematode (RKN), galling index and RI among the genotypes tested. The study revealed that cowpea genotypes SARI 1-4-90, Padi tuya, Songotra, IT99K-1122, Sanzi and Apagbaala were moderately resistant whereas cowpea genotypes IT86D-610, Zaayura, SARI 5-5-5 and IT07K-299-6 were slightly resistant. Thus, the six moderately resistant cowpea genotypes were suggested to be used as a source of resistance to RKN in future breeding works