scholarly journals NEW WAY OF CONTROLLING Oryctes monoceros (COLEOPTERA, DYNASTIDAE), A COCONUT PEST IN GHANA

CORD ◽  
2004 ◽  
Vol 20 (01) ◽  
pp. 34
Author(s):  
René Philippe ◽  
S.K. Dery
Keyword(s):  
West Africa ◽  
Oil Palm ◽  
Cover Crop ◽  
Chemical Control ◽  
Low Level ◽  
Physical Control ◽  
Frequent Monitoring ◽  
Lambda Cyhalothrin ◽  
Highly Effective

  Oryctes monoceros is one of the most dangerous pests in young coconut and oil palm plantings throughout West Africa. This species is controlled using different methods that can be applied in combination as part of IPM. The first naturally involves eliminating all larva sites, consisting of dead or felled coconut or oil palm stems. Rapidly covering felled stems with a cover crop can keep the populations of this pest down to a very low level. When adults attack, frequent monitoring of young plantings is recommended, as is the removal of adults from their galleries using a metal mini-harpoon. Chemical control with Lambda-Cyhalothrin reduces damage to seedlings, particularly as that product has good repellent properties. It remains effective for around a month. Physical control has been developed, using old fishing nets rolled into balls and inserted in the axils of young fronds. This method is highly effective, cheaper than other types of control, does not pollute and is not toxic for handlers. Adults trapped by the rolled up fishing nets, which eventually die, attract other adults that are trapped in turn, thereby increasing the efficiency of the method.

scholarly journals Low-level stratiform clouds and dynamical features observed within the southern West African monsoon

2019 ◽  
Vol 19 (13) ◽  
pp. 8979-8997 ◽  
Author(s):  
Cheikh Dione ◽  
Fabienne Lohou ◽  
Marie Lothon ◽  
Bianca Adler ◽  
Karmen Babić ◽  
...  
Keyword(s):  
West Africa ◽  
Boreal Summer ◽  
Time Range ◽  
Atmospheric Conditions ◽  
Low Level ◽  
Stratus Clouds ◽  
Stratiform Clouds ◽  
Monsoon Flow ◽  
Low Level Jet ◽  
Core Height

Abstract. During the boreal summer, the monsoon season that takes place in West Africa is accompanied by low stratus clouds over land that stretch from the Guinean coast several hundred kilometers inland. Numerical climate and weather models need finer description and knowledge of cloud macrophysical characteristics and of the dynamical and thermodynamical structures occupying the lowest troposphere, in order to be properly evaluated in this region. The Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) field experiment, which took place in summer 2016, addresses this knowledge gap. Low-level atmospheric dynamics and stratiform low-level cloud macrophysical properties are analyzed using in situ and remote sensing measurements continuously collected from 20 June to 30 July at Savè, Benin, roughly 180 km from the coast. The macrophysical characteristics of the stratus clouds are deduced from a ceilometer, an infrared cloud camera, and cloud radar. Onset times, evolution, dissipation times, base heights, and thickness are evaluated. The data from an ultra-high-frequency (UHF) wind profiler, a microwave radiometer, and an energy balance station are used to quantify the occurrence and characteristics of the monsoon flow, the nocturnal low-level jet, and the cold air mass inflow propagating northward from the coast of the Gulf of Guinea. The results show that these dynamical structures are very regularly observed during the entire 41 d documented period. Monsoon flow is observed every day during our study period. The so-called “maritime inflow” and the nocturnal low-level jet are also systematic features in this area. According to synoptic atmospheric conditions, the maritime inflow reaches Savè around 18:00–19:00 UTC on average. This timing is correlated with the strength of the monsoon flow. This time of arrival is close to the time range of the nocturnal low-level jet settlement. As a result, these phenomena are difficult to distinguish at the Savè site. The low-level jet occurs every night, except during rain events, and is associated 65 % of the time with low stratus clouds. Stratus clouds form between 22:00 and 06:00 UTC at an elevation close to the nocturnal low-level jet core height. The cloud base height, 310±30 m above ground level (a.g.l.), is rather stationary during the night and remains below the jet core height. The cloud top height, at 640±100 m a.g.l., is typically found above the jet core. The nocturnal low-level jet, low-level stratiform clouds, monsoon flow, and maritime inflow reveal significant day-to-day and intra-seasonal variability during the summer given the importance of the different monsoon phases and synoptic atmospheric conditions. Distributions of strength, depth, onset time, breakup time, etc. are quantified here. These results contribute to satisfy the main goals of DACCIWA and allow a conceptual model of the dynamical structures in the lowest troposphere over the southern part of West Africa.

Food Production in the Forest Zone of West Africa: Archaeological and Historical Perspectives

2017 ◽  
Author(s):  
Richard T. Chia ◽  
A. Catherine D'Andrea
Keyword(s):  
West Africa ◽  
Oil Palm ◽  
Tree Species ◽  
Food Production ◽  
West African ◽  
Before Present ◽  
The West ◽  
Forest Zone ◽  
Historical Perspectives ◽  
Indigenous Tree Species

Recent narratives on the origin of food production in the West African forest zone have replaced earlier diffusion-based models with viewpoints that emphasize the diversity of sources for plants and animals exploited and domesticated in the region. Management of indigenous tree species, including oil palm and incense tree, managed first by indigenous foragers, have the longest history in the area, dating back to over 8,400 before present (bp). After the 4th millennium bp, domesticates such as pearl millet, cowpea, and domestic caprines were introduced from adjacent Sahel and the savanna regions, and populations began to favor oil palm over incense tree. The mechanisms of these introductions are less clear but likely involved both diffusion and/or movements of peoples who became sedentary to varying degrees. Palaeoenvironment is an important factor to consider in tracking the development of food production in the forest zone; however, some combination of natural and human-mediated changes took place, the nature of which was not uniformly distributed.

scholarly journals Correction to: Allometric equations for estimating oil palm stem biomass in the ecological context of Benin, West Africa

Trees ◽  
2018 ◽  
Vol 33 (1) ◽  
pp. 315-315
Author(s):  
Hervé Nonwègnon Sayimi Aholoukpè ◽  
Bernard Dubos ◽  
Philippe Deleporte ◽  
Albert Flori ◽  
Lucien Guillaume Amadji ◽  
...  
Keyword(s):  
West Africa ◽  
Oil Palm ◽  
Allometric Equations ◽  
Ecological Context ◽  
Stem Biomass

scholarly journals What controls the formation of nocturnal low-level stratus clouds over southern West Africa during the monsoon season?

2019 ◽  
Vol 19 (21) ◽  
pp. 13489-13506 ◽  
Author(s):  
Karmen Babić ◽  
Norbert Kalthoff ◽  
Bianca Adler ◽  
Julian F. Quinting ◽  
Fabienne Lohou ◽  
...  
Keyword(s):  
Boundary Layer ◽  
West Africa ◽  
Climate Models ◽  
Marine Boundary Layer ◽  
Monsoon Season ◽  
Onset Time ◽  
Data Set ◽  
Cold Air ◽  
Low Level ◽  
Stratus Clouds

Abstract. Nocturnal low-level stratus clouds (LLCs) are frequently observed in the atmospheric boundary layer (ABL) over southern West Africa (SWA) during the summer monsoon season. Considering the effect these clouds have on the surface energy and radiation budgets as well as on the diurnal cycle of the ABL, they are undoubtedly important for the regional climate. However, an adequate representation of LLCs in the state-of-the-art weather and climate models is still a challenge, which is largely due to the lack of high-quality observations in this region and gaps in understanding of underlying processes. In several recent studies, a unique and comprehensive data set collected in summer 2016 during the DACCIWA (Dynamics-aerosol-chemistry-cloud interactions in West Africa) ground-based field campaign was used for the first observational analyses of the parameters and physical processes relevant for the LLC formation over SWA. However, occasionally stratus-free nights occur during the monsoon season as well. Using observations and ERA5 reanalysis, we investigate differences in the boundary-layer conditions during 6 stratus-free and 20 stratus nights observed during the DACCIWA campaign. Our results suggest that the interplay between three major mechanisms is crucial for the formation of LLCs during the monsoon season: (i) the onset time and strength of the nocturnal low-level jet (NLLJ), (ii) horizontal cold-air advection, and (iii) background moisture level. Namely, weaker or later onset of NLLJ leads to a reduced contribution from horizontal cold-air advection. This in turn results in weaker cooling, and thus saturation is not reached. Such deviation in the dynamics of the NLLJ is related to the arrival of a cold air mass propagating northwards from the coast, called Gulf of Guinea maritime inflow. Additionally, stratus-free nights occur when the intrusions of dry air masses, originating from, for example, central or south Africa, reduce the background moisture over large parts of SWA. Backward-trajectory analysis suggests that another possible reason for clear nights is descending air, which originated from drier levels above the marine boundary layer.

scholarly journals Genotypic variability in oil palm (Elaeis guineensis Jacq.) towards drought damages in Benin (West Africa)

2019 ◽  
Vol 13 (3) ◽  
pp. 1737
Author(s):  
Louis Wilfried Yehouessi ◽  
Léifi Nodichao ◽  
Hubert Adoukonou-Sagbadja ◽  
Corneille Ahanhanzo
Keyword(s):  
West Africa ◽  
Oil Palm ◽  
Elaeis Guineensis ◽  
Genotypic Variability

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF OIL PALM (ELAEIS GUINEENSIS): A REVIEW

2011 ◽  
Vol 47 (4) ◽  
pp. 629-652 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
West Africa ◽  
Soil Water ◽  
Water Use ◽  
Water Relations ◽  
Oil Palm ◽  
Water Productivity ◽  
Background Information ◽  
Flower Initiation ◽  
Irrigation Interval ◽  
Best Estimates

SUMMARYThe results of research on the water relations and irrigation need of oil palm are collated and summarized in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information is given on the centres of origin (West Africa) and of production of oil palm (Malaysia and Indonesia), but the crop is now moving into drier regions. The effects of water stress on the development processes of the crop are summarized followed by reviews of its water relations, water use and water productivity. The majority of the recent research published in the international literature has been conducted in Malaysia and in Francophone West Africa. The unique vegetative structure of the palm (stem and leaves) together with the long interval between flower initiation and the harvesting of the mature fruit (ca. three years) means that causal links between environmental factors (especially water) and yield are difficult to establish. The majority of roots are found in the 0–0.6 m soil horizons, but roots can reach depths greater than 5 m and spread laterally up to 25 m from the trunk. The stomata are a sensitive indicator of plant water status and play an important role in controlling water loss. Stomatal conductance and photosynthesis are negatively correlated with the saturation deficit of the air. It is not easy to measure the actual water use of oil palm, the best estimates for mature palms suggesting crop evapotranspiration (ETc) rates of 4–5 mm d−1 in the monsoon months (equivalent to 280–350 l palm−1 d−1). For well-watered mature palms, crop coefficient (Kc) values are in the range 0.8–1.0. Although the susceptibility of oil palm to drought is well recognized, there is a limited amount of reliable data on actual yield responses to irrigation. The best estimates are 20–25 kg fresh fruit bunches ha−1 mm−1 (or a yield loss of about 10% for every 100 mm increase in the soil water deficit). These increases are only realized in the third and subsequent years after the introduction of irrigation and follow an increase in the number of fruit bunches as a result of an improvement in the sex ratio (female/total inflorescence production) and a reduction in the abortion of immature inflorescences. There is no agreement on the allowable depletion of the available soil water, or on the associated optimum irrigation interval. Drip irrigation has been used successfully on oil palm.

scholarly journals The observed diurnal cycle of nocturnal low-level stratus clouds over southern West Africa: a case study

2018 ◽  
Author(s):  
Karmen Babić ◽  
Bianca Adler ◽  
Norbert Kalthoff ◽  
Hendrik Andersen ◽  
Cheikh Dione ◽  
...  
Keyword(s):  
Relative Humidity ◽  
West Africa ◽  
Diurnal Cycle ◽  
Heat Budget ◽  
Cloud Base ◽  
Radiative Cooling ◽  
Continuous Increase ◽  
Low Level ◽  
Budget Analysis ◽  
Wide Range

Abstract. This study presents the first detailed observational analysis of the complete diurnal cycle of stratiform low-level clouds (LLC) and involved atmospheric processes over southern West Africa. The data used here were collected during the comprehensive DACCIWA (Dynamics-Aerosol-Chemistry-Cloud-Interactions in West Africa) ground-based campaign, which aimed at monitoring LLC characteristics and capturing the wide range of atmospheric conditions related to the West African monsoon flow. In this study, in-situ and remote sensing measurements from the supersite near Savè (Benin) collected during a typical day, which is characterized by the onset of a nocturnal low-level jet (NLLJ) and the formation of LLC, are analyzed. The associated dynamic and thermodynamic conditions allow the identification of five different phases of the LLC diurnal cycle: the Stable, Jet, Stratus I, Stratus II and Convective phase. The analysis of relative humidity tendency shows that cooling is a dominant process for LLC formation, which leads to a continuous increase of relative humidity at a maximum rate of 6 % per hour, until finally saturation is reached and LLC form with a cloud-base height near the height of NLLJ maximum. Results of heat budget analysis illustrate that horizontal cold air advection, related to the maritime inflow, which brings the cool maritime air mass and a prominent NLLJ wind profile, has the dominant role on the observed strong cooling of −1.2 K per hour during the Jet phase. The contribution from horizontal cold advection is quantified to be up to 72 %, while radiative cooling and sensible heat flux divergence contribute with 16 and 12 %, respectively, to the observed heat budget below the NLLJ maximum. After the LLC form (Stratus phase I and II), turbulent mixing is an important factor leading to the cooling below the cloud base, while strong radiative cooling at the cloud top helps to maintain thick stratus.

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