The efficacy of some botanicals and bio-agents were assessed in vitro as the potential biofungicides against Fusarium verticillioides, the causal organism of stalk rot disease of maize plant. The botanicals used in this study were Morinda lucida (Oruwo) and Tithonia diversifolia (Mexican Sunflower) and the bio-agents used were Trichoderma viride, Trichoderma harzianum, Trichoderma pseudokoningii and Bacillius subtilis. All the plant extracts and antagonistic organisms significantly inhibited the growth of Fusarium verticillioides. However, out of the antagonists, T. viride provided the highest inhibitory effect followed by T. pseudokoningii, T. harzianum, and B. subtilis which was the lowest suppressive antagonist. The extract from T. diversifolia, provided the highest inhibitory effect followed by M. lucida.

Fall armyworm (FAW; Spodoptera frugiperda), an exotic moth which recently invaded Africa, is a highly destructive pest of cereals especially maize a highly valued staple crop in Nigeria. The use of natural enemies such as predators or parasitoids for FAW control is more economically viable and environmentally safer than currently recommended synthetic insecticides. Natural enemies to combat the pest have not yet been reported in Nigeria. An exploration for the pests’ natural enemies was undertaken by collecting FAW eggs and larvae from maize fields. These were reared in the laboratory for emergence, identification and efficacy as natural enemies. This yielded Euplectrus laphygmae (Hymenoptera: Eulophidae); Telenomus remus (Hymenoptera: Platygastridae) and Trombidium sp. (Acari.: Trombidiidae). Cotesia or Apanteles spp. were inferred to occur since Stictopisthus sp. (Hym.: Ichneumonidae), a secondary parasitoid, that attacks cocoons of Microgasterinae (e.g. Cotesia, Apanteles etc.) also emerged. Species of yet-to-be identified predators were also observed in various niches of maize plants. A positive relationship was found between FAW instar and the number of E. laphygmae eggs/instar ranging, on average, from 1.5 on second instar to 5.5 on fourth instars hosts. Parasitism rate of T. remus on FAW eggs was 100%. Parasitic mite infestation resulted in increasing paleness, reduced feeding, growth and movement as well as death of FAW 1st instars. Thus, the occurrence of FAW natural enemies in Nigeria calls for advocacy campaign to incorporate their use into integrated pest management strategies that attract and allow natural enemies to thrive for FAW management.

The study investigated the in-vitro antifungal activities of sodium bicarbonate (NaHCO3) and leaf extracts of Vernonia amydgalina (bitter leaf) and Azadirachta indica (neem) on fungal species isolated from two cowpea cultivars; IFE BROWN and Drum (a local cultivar). Concentrations of 1.95 mg/ml and 1.43 mg/ml were used for A. indica while 1.45 mg/ml and 1.15 mg/ml were used for V. amydgalina. Sodium bicarbonate was evaluated on all the isolates at 2.0 mg/ml and 3.0 mg/ml. The inhibitory effects of these antifungal agents were compared with benlate (a synthetic fungicide) on Potato Dextrose Agar. Benlate totally inhibited all the fungal isolates. Candida species isolated from the two cowpea cultivars were greatly inhibited by the antifungal agents while Trichoderma species isolated from IFE BROWN was the least inhibited. The inhibitory effects of NaHCO3 and A. indica on Candida spp. were not significantly different and values ranged from 74.5% to 84%. The two concentrations of A. indica had better inhibitory effect on Pythium spp. than NaHCO3. Vernonia amydgalina at 1.45 mg/ml inhibited A. niger and Candida spp. by 83.75% and 87.5% respectively while NaHCO3 at 2.0 mg/ml inhibited Rhizopus stolonifer isolated from Drum by 75%. The study concludes that the two plant extracts and sodium bicarbonate had broad spectrum activities on fungal species and are therefore recommended as alternatives to toxic and synthetic fungicides.

A screen house experiment was carried out to determine the effect of organic fertilizer, compost, inorganic fertilizer, and single super phosphate and Arbuscular mycorrhiza on damping-off disease of cowpea. The experimental design used was completely randomized design (CRD). There were fifteen treatments which were replicated three times. 2g of Macrophomina phaseolina (damping off disease) was infested on 10kg of soil sample in each pot with (30 by 75) cm spacing. Arbuscular mycorrhiza, compost (poultry based) and single super phosphate (SSP) were applied at the rate of 2250kg/ha, 1670kg/ha and 676kg/ha respectively. Three seeds of cowpea were sown into each pot, but later thinned into two plants per pot. Data on germination percentage at 7, 14, 21 and 28 days, number of leaves of cowpea at 2, 4, 6 and 8 weeks after planting, weight of pods per plant, incidence and severity at which pathogens affected the cowpea plant per treatment and growth yield of each treatment were collected and analyzed using analysis of variance (ANOVA) and means separated using the Duncan multiple range test. The plants that were treated with 676kg/ha single super phosphate produced higher cumulative weight of harvested fruits per plant followed by Arbuscular mycorrhiza, which did not have any negative effect on environment. The values of phosphorus in the post harvest soil analysis revealed that lower values of phosphorus were recorded in Single Super Phosphate treated pots, while plants treated with Arbuscular mycorrhiza at 500kgha -1 produced higher P value than the preplanting soil analysis indicating the absorption of large amount of the elements. It was therefore recommended that Arbuscular mycorrhiza could be used to optimize seed yield in cowpea.

No abstract