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The economic return for peanut (Arachis hypogaea L.) in Ghana is often low due to limitations in the availability of inputs or their adoption, which are needed to optimize yield. Six experiments were conducted in Ghana in 2020 and 2021 to determine the impact of planting date, cultivar, fertilization, pest management practices, and harvest date on peanut yield, financial return, and pest reaction. A wide range of interactions among these treatment factors were often observed for infestations of aphids (Aphis gossypii Glover); groundnut rosette disease (Umbravirus: Tombusviridaee); millipedes (Peridontopyge spp.); white grubs (Schyzonicha spp.); wireworms (Conoderus spp.); termites (Microtermes and Odontotermes spp.); canopy defoliation as a result of early leaf spot disease caused by Passalora arachidicola (Hori) and late leaf spot caused by Nothopassalora personata (Berk. and M. A. Curtis); and the scarification and boring of pods caused by arthropod feeding. Pod yield and economic return increased for the cultivar Chitaochi and Sarinut 2 when fertilizer was applied and when fertilizer was applied at early, mid-, and late planting dates. Pod yield and economic return increased when a combination of locally derived potassium soaps was used for aphid suppression and one additional hand weeding was used in the improved pest management practice compared with the traditional practice without these inputs. Pearson correlations for yield and economic return were negatively correlated for all pests and damage caused by pests. The results from these experiments can be used by farmers and their advisors to develop production packages for peanut production in Ghana. [ABSTRACT FROM AUTHOR]

Invasive alien species (IAS) continue to shape the global landscape through their effects on biological diversity and agricultural productivity. The effects are particularly pronounced in Sub-Saharan Africa, which has seen the arrival of many IAS in recent years. This has been attributed to porous borders, weak cross border biosecurity, and inadequate capacity to limit or stop invasions. Prediction and early detection of IAS, as well as mechanisms of containment and eradication, are needed in the fight against this global threat. Horizon scanning is an approach that enables gathering of information on risk and impact that can support IAS management. A study was conducted in Ghana to establish two ranked lists of potential invasive alien plant pest species that could be harmful to agriculture, forestry, and the environment, and to rank them according to their potential threat. The ultimate objective was to enable prioritization of actions including pest risk analysis, prevention, surveillance and contingency plans. Prioritisation was carried out using an adapted version of horizon scanning and consensus methods developed for ranking IAS worldwide. Following a horizon scan of invasive alien species not yet officially present in Ghana, a total of 110 arthropod and 64 pathogenic species were assessed through a simplified pest risk assessment. Sixteen species, of which 14 were arthropods and two pathogens, had not been recorded on the African continent at the time of assessment. The species recorded in Africa included 19 arthropod and 46 pathogenic species which were already recorded in the neighbouring countries of Burkina Faso, Côte d'Ivoire, and Togo. The majority of arthropod species were likely to arrive as contaminants on commodities, followed by a sizable number which were likely to arrive as stowaways, while some species were capable of long distance dispersal unaided. The main actions suggested for species that scored highly included full pest risk analyses and, for species recorded in neighbouring countries, surveys to determine their presence in Ghana were recommended. [ABSTRACT FROM AUTHOR]

In the late 1970s, Benckert and Wachter (Technical University Stuttgart) tested labyrinth seals using air as the test media and measured direct and cross-coupled stiffness coefficients. They reported the following results: (1) fluid preswirl in the direction of shaft rotation creates destabilizing cross-coupled stiffness coefficients and (2) effective swirl brakes at the inlet to the seal can markedly reduce the cross-coupled stiffness coefficients, in many cases reducing them to zero. In recent years, "negative-swirl" swirl brakes have been employed, which attempt to reverse the circumferential direction of inlet flow, changing the sign of the cross-coupled stiffness coefficients and creating stabilizing stiffness forces. This study presents test results for a 16-tooth labyrinth seal with positive inlet preswirl (in the direction of shaft rotation) for the following inlet conditions: (1) no swirl brakes, (2) straight, conventional swirl brakes, and (3) negative-swirl swirl brakes. The negative-swirl swirl-brake designs were developed based on computational fluid dynamics (CFD) predictions. Tests were conducted at 10.2, 15.35, and 20.2 krpm with 70 bar of inlet pressure for pressure ratios of 0.3, 0.4, and 0.5. Test results include leakage and rotordynamic coefficients. In terms of leakage, the negative-swirl brake configuration leaked the least, followed by the conventional brake, followed by the no-brake design. Normalized to the negative-swirl brake configuration, the conventional-brake and no-brake configurations mass flow rate was greater, respectively, by factors of 1.04 and 1.09. The direct-stiffness coefficients are negative but small, consistent with past experience. The conventional swirl brake drops the destabilizing cross-coupled stiffness coefficients k by a factor of about 0.8 as compared to the no-brake results. The negative-swirl brake produces a change in sign of k with an appreciable magnitude; hence, the stability of forward precessing modes would be enhanced. In descending order, the direct-damping coefficients C are: no-swirl, negative-swirl, and conventional-swirl. Normalized in terms of the no-swirl case, C for the negative and conventional brake designs is, respectively, 0.7 and 0.6 smaller. The effective damping Ceff combines the effect of k and C. Ceff is large and positive for the negative-swirl configuration and near zero for the no-brake and conventional-brake designs. The present results for a negative-brake design are very encouraging for both eye-packing seals (where conventional swirl brakes have been previously employed) and division-wall and balance-piston seals, where negative shunt injection has been employed. [ABSTRACT FROM AUTHOR]