Tied-ridge techniques have not been used to improve seed yield in cowpeas, so experiments were conducted in Burkina Faso in the Sudan savannah zone on an Alfisol at five slope-positions on the toposequence, using two dates of planting for three consecutive years; and in the northern Guinea savannah zone, at a mid-slope position on an Oxisol with one date of planting for two consecutive years. In these trials, the effect of planting cowpeas on tied-ridge seedbeds was compared with planting on the ...

Twenty-three provenances of Gliricidia sepium and eleven isolines of Leucaena leucocephala were examined at a low and at high phosphate levels (20 and 80 mg P kg-1 soil) for growth, phosphate (P) uptake and use efficiency. Large differences in growth at the low P level, and in growth response to the higher P rate occurred among L. leucocephala isolines and G. sepium provenances. Shoot dry weight atlow P varied from 1.30 to 3.01 g plant-1 for L. leucocephala and from 1.44 to 3.07 g plant-1 for G ...

Soil erosion, measured in field runoff plots, was correlated with several rainfall erosivity indices. Erosion was measured on field plots established on a Typic Paleudult in southeastern Nigeria. Several erosivity indices were computed from a daily recording rain gauge sited in vicinity of the runoff plots. Erosivity indices computed included EI30 (WISCHMEIER & SMITH 1978), KE>1 (HUDSON 1971) and AIm (LAL 1976). In addition, several new indices were computed including EkIm and EkI30, where, the ...

The effect of alley cropping with seven combinations of Acioa and Leucaena hedgerows and a control (no hedgerow) treatment on sequentially cropped maize and cowpea was studied in 1985 and 1986. The trial was carried out on an Alfisol in the humid zone of southwestern Nigeria. Hedgerows were established in 1983, using 4 m interhedgerow spacing and pruned to 25 cm height during cropping. Highest dry matter, wood, and nutrient yields of prunings of Acioa and Leucaena hedgerows were obtained with sole ...

The spatial distribution of five lepidopterous pests, Sesamia calamistis Hampson (Noctuidae), Eldana saccharina Walker (Pyralidae), Spodoptera exempta (Walker) (Noctuidae), Mussidia nigrivenella (Ragonot) (Pyralidae), and Cryptophlebia leucotreta (Meyrick) (Tortricidae), on maize in West Africa is described using Taylor's power law and the relationship of proportion of infested plants to the mean density. All five species showed a highly aggregated distribution, with Taylor's indices of aggregation ...

A biotype of the annual grass weed hare barley infesting an alfalfa field with a 24-yr history of the use of the bipyridylium herbicides paraquat and diquat, was investigated for resistance to these herbicides. Rates of up to 800 g ai ha–1 of each herbicide caused no mortality in the hare barley plants from this field. The same species, collected from an adjacent pasture field with no history of bipyridylium herbicide application, exhibited LD50's of 57 and 160 g ai ha–1 for paraquat and diquat, ...

Density-specific sampling plans were developed under African conditions for the exotic spider mite, Mononychellus tanajoa (Bondar), a serious pest of cassava, Manihot esculenta. The within-plant distribution of Mononychellus tanajoa was found to favour new foliage, regardless of time of planting or plant age. Consequently, the first developed leaf near the top of the foliage was selected as the sampling unit and related to whole plant populations of M. tanajoa. The relationship between the mite ...

Clonal trials with the West African hardwood Triplochiton scleroxylon, K. SCHUM. have indicated a positive relationship between stem size (height and diameter) and branching frequency (mean no. of branches per m of mainstem). As part of a programme of vegetative propagation and clonal selection, the present study with young plants examined clonal variation in apical dominance, the process which determines branching frequency. Young potted plants of five clones were decapitated by removing the apex ...

Plantain (Musa spp., AAB group) cultivation is threatened by black sigatoka, an airborne fungal (Mycosphaerella fijiensis Morelet) leaf spot disease. Several traits in plantains and bananas are mainly affected by major genes. The host resistance response to black sigatoka is under the control of at least three different genes, one major recessive gene bs1 and two other independent additive alleles. Diploid and tetraploid plantain hybrids were evaluated for bunch weight, fruit weight, fruit length ...

Life history traits of the mango mealybug, Rastrococcus invadens Williams, were compared between two neighboring mango trees (Mangifera indica L.), one of which was heavily infested and the other slightly infested. On the infested tree, mealybug survival was high because of good feeding conditions and low escape. The pre‐reproductive period of mealybugs on the heavily infested tree was shorter and total offspring production higher than that of mealybugs on the uninfested tree. This significantly ...