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Journal and Journal Articles: Recent submissions
Now showing items 1901-1920 of 5157
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First report of banana streak badnavirus in plantain landraces in southern Cameroon, Central Africa
(1997)Banana streak badnavirus (BSV) has been reported from Musa spp. in many parts of West Africa, including Benin, Côte d'Ivoire, Ghana, and Nigeria (1). Symptoms of BSV infection in Musa spp. are sometimes similar to and confused with those caused by cucumber mosaic virus (CMV). BSV is prevalent in areas of southern Nigeria bordering Cameroon, and the disease may also be present in other Central African countries. In June 1996, six leaf samples with viruslike yellow/chlorotic streak symptoms were ... -
Decisionmaking by smallholder farmers in an oil plambased economy in southern Benin, West Africa
(1997)Budgets for palm-oil and palm-alcohol production were constructed to show the economic benefit of each activity to smallholder farmers in southern Benin. The selling prices of oil palms to alcohol distillers, who cut the trees, were approximately equal to the annual fruit revenue for that tree. Since trees produce fruit for several decades, this price seems very low. A life-table analysis of the trees was conducted after converting tree height to tree age and substituting revenue for offspring. ... -
Aspergillus flavus infection and aflatoxin contamination of preharvest maize in the Republic of Benin
(1997)Eighty and sixty maize fields were sampled in 1994 and 1995, respectively, to monitor Aspergillus infection and aflatoxin contamination of preharvest maize in Benin. Three Aspergillus species were isolated from different agroecological zones, with A. flavus being the most prevalent. The countrywide mean percentage of kernel infection was about 20% in both years. Aflatoxin was extracted from maize in at least 30% of the fields sampled. Toxin concentrations exhibited a distinct zonal variation, with ... -
Infestation of maize by Prostephanus truncatus initiated by maleproduced pheromone
(1997)Delta traps baited with maize cobs, which were infested each with one male Prostephanus truncatus (Horn) (Col.: Bostrichidae), were distributed in southern Benin and collected after one, two, three and four weeks. The numbers of P. truncatus caught during the different trapping periods were not significantly different. Sixty‐four percent of the trapped P. truncatus were females. Females attracted during the one‐week trapping period produced a mean of 6.9 progeny during the seven days. The sex ratio ... -
First report of Curvularia lunata associated with stem disease of cassava
(1997)During surveys covering 60 cassava (Manihot esculenta Crantz) fields, randomly selected (between latitude 4°55′N and 8°16′N) in south Ghana, and 27 fields in southeast (between 4°50′N and 7°56′N) Nigeria, 8-month-old or older stems of some cassava genotypes were found to be covered by grayish brown lesions, predominantly on lignified portions of stems. Field disease incidence ranged from 0 to 80%, and severity from no disease to highly affected (>15 lesions per stem). To identify the pathogen, ... -
Integrated croplivestock systems in subSaharan Africa: an option or imperative?
(1997)Rapid growth of the human and livestock populations in sub-Saharan Africa is creating unprecedented increases in food and feed demands. These population pressures on a fixed landbase are likely to promote severe competition for resources and drive agriculture progressively towards intensification. Integrated crop-livestock systems, already common in the highlands, are expected to evolve rapidly elsewhere. Research is required to develop technological alternatives which promote better resource use ... -
Oligonucleotide fingerprinting detects genetic variability at different levels in Nigerian Mycosphaerella fijiensis
(1997)DNA fingerprinting with synthetic simple repetitive oligonucleotides such as (CA)8 or (CAA)5 detected polymorphisms between various isolates of the ascomycete Mycosphaerella fijiensis, the causal agent of the black Sigatoka disease of Musa. These microsatellite motifs are present at multiple chromosomal locations and in high copy numbers in the Mycosphaerella genome, generating informative fingerprints with low background. Variability exists on a macro‐ as well as a microgeographical scale: it ... -
The efficiency of natural and artificial pollinators in plantain (Musa spp. AAB group) hybridisation and seed production
(1997)Plantain-derived tetraploid hybrids are routinely crossed In Musa breeding programmes with diploid Musa accessions for the efficient generation of putative triploid hybrid seed. However, natural open pollination of these same tetraploid hybrids also consistently generates viable seed. The mean germination rate of such open pollinated seed was observed to be higher than that of seed generated from artificial pollinations. This may suggest that tetraploid Musa hybrids played a much more important ... -
Determinants of mechanized cassava processing technology adoption in West Africa
(1997)This paper aims to identify the determinants of adoption of mechanized processing technologies in cassava processing. The paper is based on information collected at the farm-level in ten major cassava producing countries of Africa within the context of the Collaborative Study of Cassava in Africa. High labour requirement, especially female labour is a constraint to processing of cassava into certain products. Mechanized machines for performing certain processing tasks have been available for nearly ... -
Influence of cassava mosaic virus on cassava leaf vegetable quality
(1989)People of Zaire prefer cassava mosaic virus-infected cassava leaves to the healthy leaves for vegetable use. The diseased leaves are believed to be sweeter and more tender. To investigate this claim, leaves from three cassava clones, TMS 50395, TMS 30572 and Isunikankiyan, with disease ratings of one to five, were analysed for total cyanide (free and bound), protein (N x 6.25), total soluble sugars and crude fibre. Total cyanide concentration decreased significantly in the three clones with ... -
Effect of seed size and phosphorus fertilization on growth of selected legumes
(1997)A screenhouse experiment was conducted to assess the effects of seed size and phosphorus (P) fertilization on growth of 12 herbaceous and shrub legumes [Arachis hypogaea, Cajanus cajan, Centrosema pascuorum, Centrosema brasilianum, Crotolaria ochroleuca, Glycine max, Lablab purpureus, Mucuna cochinchinensis, Mucuna pruriens var. utilis (black seed), Mucunapruriens (white seed), Pueraria phaseoloidesand Vigna unguiculata] grown on a P‐deficient Plinthustalf. Species with large seed size showed ... -
In vitro plant regeneration via organogenesis of cowpea [ Vigna unguiculata (l.) Walp]
(1997)Shoot regeneration via organogenesis was achieved from axenic cowpea [Vigna unguiculata subsp. unguiculata L. (Walp.) Verde.] hypocotyls and cotyledons of advanced breeding lines and varieties. Cotyledons and embryos were excised from green immature pods. The apical parts of the embryos were removed and the hypocotyls were transferred to regeneration media. Cotyledons and hypocotyls were tested on media with gradients of several hormonal and putrescine combinations. Cowpea cotyledons and hypocotyls ... -
Survey on cowpea virus incidence and distribution in Nigeria
(1997)Enzyme-linked immunosorbent assay (ELISA) was used to detectviruses in649 cowpea leafsamples collectedfrom115 fields during a 3-year survey carried out from 1991 to 1993 throughout all agroecological zones in Nigeria. Six viruses, cowpea aphid-borne mosaic potyvirus (CAMV), blackeye cowpea mosaic potyvirus (BICMV), southern bean mosaic sobemovirus (SBMV), cowpea mottle carmovirus (CMoV), cowpea (yellow) mosaic comovirus (CpMV) and the cowpea strain of cucumbermosaic cucumovirus (CMV-CS)were ... -
Cowpea embryo rescue: influence of culture media composition on plant recovery from isolated immature embryos
(1997)Factors responsible for successful rescue of immature embryos of cowpea [Vigna unguiculata (L.) Walp.] and V. vexillata (L.) and for in vitro embryo development were studied. A new basal medium for embryo development in vitro was formulated on the basis of the mineral composition of embryos. Sucrose, fructose and glucose were compared as carbohydrate sources. The highest frequency of embryos developing into plants was obtained with sucrose. Adding casein hydrolysate to the medium increased plant ... -
Movement of Cicadulina storeyi [Homoptera:Cicadellidae] in maize fields and its behavior in relation to maize growth stage
(1997)The movement of Cicadulina storeyi China (Homoptera: Cicadellidae), vector of maize streak geminivirus, within maize (Zea mays L.) fields was studied using mark, release and recapture experiments. Cicadulina storeyi, marked with fluorescent dye, were released at dusk and monitored for 14 days using yellow sticky traps placed at different distances (5–160 m) and directions from the release point. The suitability of maize growth stage for settling by C. storeyi was also investigated. Catches decreased ... -
Economic analysis of soil erosion effects in alley cropping, notill and bush fallow systems in southwestern Nigeria
(1990)Most upland soils in humid and sub-humid tropical Africa are characterized by low inherent fertility and are also susceptible to soil erosion and compaction with cultivation. Based on simulation model, this study uses a capital budgeting approach to determine the profitability of alternative land use systems, taking into account the short and long-run impact of soil erosion on agricultural productivity in southwestern Nigeria. The fallow systems include: (1) two continuous cultivation alley cropping ... -
Use of Metarhizium flavoviride for control of Zonocerus variegatus: a model, relating mortality in caged field samples with disease development in the field
(1997)A field trial was conducted using an oil formulation of the entomopathogenic fungus, Metarhizium flavoviride Gams & Rozyspal (Deuteromycotina: Hyphomycetes), to control the variegated grasshopper, Zonocerus variegatus L. (Orthoptera: Pyrgomorphidae). The influence of dispersal and secondary pick‐up from the spray residue on mortality was assessed by sampling insects from the treated plots at intervals and monitoring disease levels during subsequent incubation in the laboratory. The cumulative ... -
The effect of pathogen dosage on the pathogenicity of Neozygites floridana (Zygomycetes:Entomophthorales) to Mononychellus tanajoa (Acari: Tetranychidae)
(1997)How the pathogen inoculum size affects the pathogenicity of Neozygites floridanatoMononychellus tanajoawas studied at 28°C, 12L:12D photoperiod and 90–100% RH. All inoculum sizes tested (one, two, four, six, and eight capilliconidia per mite) were lethal. Dead mites started to appear 48 hr after exposure to the conidia. Inoculum size significantly affected time to mortality. All mites exposed to six or eight capilliconidia died of mycosis 57.1 and 62.9 hr, respectively, after infection. At smaller ...
