Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Correction to: Unravelling the variability and causes of smallholder maize yield gaps in Ethiopia
    Assefa, Banchayehu Tessema ; Chamberlin, Jordan ; Reidsma, Pytrik ; Silva, João Vasco ; Ittersum, Martin K. van - \ 2020
    Food Security 12 (2020). - ISSN 1876-4517 - p. 489 - 490.

    The original version of this article unfortunately contained the following errors. (1) Title of co-author Pytrik Reidsma should be Associate Professor instead of Assistant Professor. (2) In Fig. 6, the explanations in the legend are switched. The corrected figure is shown here. (Figure presented.).

    Unravelling the variability and causes of smallholder maize yield gaps in Ethiopia
    Assefa, Banchayehu Tessema ; Chamberlin, Jordan ; Reidsma, Pytrik ; Silva, João Vasco ; Ittersum, Martin K. van - \ 2020
    Food Security 12 (2020)1. - ISSN 1876-4517 - p. 83 - 103.
    Production ecology - Smallholder agriculture - Stochastic frontier analysis - Sustainable intensification - Yield response to N - Zea mays L

    Ethiopia has achieved the second highest maize yield in sub-Saharan Africa. Yet, farmers’ maize yields are still much lower than on-farm and on-station trial yields, and only ca. 20% of the estimated water-limited potential yield. This article provides a comprehensive national level analysis of the drivers of maize yields in Ethiopia, by decomposing yield gaps into efficiency, resource and technology components, and accounting for a broad set of detailed input and crop management choices. Stochastic frontier analysis was combined with concepts of production ecology to estimate and explain technically efficient yields, the efficiency yield gap and the resource yield gap. The technology yield gap was estimated based on water-limited potential yields from the Global Yield Gap Atlas. The relative magnitudes of the efficiency, resource and technology yield gaps differed across farming systems; they ranged from 15% (1.6 t/ha) to 21% (1.9 t/ha), 12% (1.3 t/ha) to 25% (2.3 t/ha) and 54% (4.8 t/ha) to 73% (7.8 t/ha), respectively. Factors that reduce the efficiency yield gap include: income from non-farm sources, value of productive assets, education and plot distance from home. The resource yield gap can be explained by sub-optimal input use, from a yield perspective. The technology yield gap comprised the largest share of the total yield gap, partly due to limited use of fertilizer and improved seeds. We conclude that targeted but integrated policy design and implementation is required to narrow the overall maize yield gap and improve food security.

    Assessing farmers'willingness to participate in campaign-based watershed management : Experiences from Boset District, Ethiopia
    Assefa, Samuel ; Kessler, Aad ; Fleskens, Luuk - \ 2018
    Sustainability 10 (2018)12. - ISSN 2071-1050
    Ethiopia - Mass mobilization - Outcomes - Perceptions - Soil and water conservation - Willingness

    This study assessed farmers' perceptions of the outcomes of the Campaign-BasedWatershed Management (CBWM) program in Ethiopia, and how this influences their willingness to participate in the program. Key informant interviews, a household survey, and the Google Earth Engine were used to collect and analyze the relevant data. Results show that farmers' perceived outcomes of the CBWM program hardly motivated them to participate in the program. Particularly, farmers were not motivated by the physical effects of the program, because of the limited direct benefits to individual households, and destruction of previously developed micro-watersheds by frequent runoff and human and animal disturbances. Similarly, farmers were not motivated by the economic effects of the program, because of the limitations/absence of benefit-sharing mechanisms and resultant conflicts among farmers. The only motivating outcome of the program concerned its effect on personal capacities, which was particularly appreciated in localities that were vulnerable to erosion. The results of the study suggest the need to (1) better integrate actions at watershed level to come to effective water runoff control, (2) enhance the participation of all local actors to come to more effective area closure initiatives with transparent benefit-sharing mechanisms, and (3) give much more emphasis to capacity building as a cross-cutting component in the program. Hence, in order to enhance the willingness of farmers to genuinely participate in the CBWM, the program should adopt a more participatory and integrated approach.

    Price and Volatility Transmission and Market Power in the German Fresh Pork Supply Chain
    Assefa, Tsion Taye ; Meuwissen, Miranda P.M. ; Gardebroek, Koos ; Oude Lansink, Alfons G.J.M. - \ 2017
    Journal of Agricultural Economics 68 (2017)3. - ISSN 0021-857X - p. 861 - 880.
    Food supply chain - Germany - market power - price transmission - price volatility transmission

    We investigate the relationship between the transmission of price volatility and market power in the German fresh pork supply chain. We use a theoretical model underpinning this relationship followed by an empirical application that uses monthly farm, slaughterhouse and retail pork price data for the period 2000–2011. We examine both the relationships of market power with price level transmission and price volatility transmission in the chain. We use a vector error correction model and least squares regressions to analyse price transmission and price volatility transmissions, respectively. Results show that retail market power limited both types of transmissions. Competition inducing policy measures coupled with measures that support price risk management initiatives of chain actors are suggested.

    Improving on-site water availability by combining in-situ water harvesting techniques in semi-arid Northern Ethiopia
    Grum, Berhane ; Assefa, Dereje ; Hessel, Rudi ; Woldearegay, Kifle ; Ritsema, Coen J. ; Aregawi, Berihun ; Geissen, Violette - \ 2017
    Agricultural Water Management 193 (2017). - ISSN 0378-3774 - p. 153 - 162.
    In-situ water harvesting - Runoff - Soil-moisture content - Straw mulch - Tied ridges

    Crop production in arid and semi-arid environments is strongly affected by temporal variation of water availability during the growth period. In-situ water harvesting techniques such as tied ridges and mulching improve water availability over time and may improve crop yield. A field experiment was conducted in 2013 and 2014 in the Gule sub-watershed, Northern Ethiopia to study the effect of combining in-situ water harvesting techniques on on-site water regime, i.e., runoff and soil-moisture content. Five treatments with tied ridges, straw mulch, tied ridges and straw mulch together, straw mulch plus effective microorganisms and a combination of tied ridges, straw mulch and effective microorganisms and an untreated control were tested. Combined tied ridges and straw mulch with and without effective microorganisms significantly reduced average runoff per event by 78 and 88%, respectively, compared to the control. Tied ridges alone reduced runoff by 56% and straw mulch with and without effective microorganisms reduced runoff by 49 and 53%, respectively. Average soil-moisture content over the two years was significantly higher (22.4%) in combined tied ridges and straw mulch than the control (19.9%). Tied ridges or straw mulch alone significantly reduced runoff and improved soil-moisture content, but the two combined were more efficient. The findings suggest that combining straw mulch and tied ridges enhance water infiltration into the soil and improve water availability during the growing season, thereby protecting crops from dry periods.

    Improving food security by reducing the maize yield gap in Ethiopia
    Admassie, Assefa ; Dijk, M. van; Jongeneel, R.A. ; Morley, Tomas ; Tesfaye, Kindie ; Reidsma, P. ; Loon, M.P. van; Ittersum, M.K. van - \ 2017
    Ethiopian Economics Association (Ethiopian Economic Associations newsletter 01) - 4 p.
    Stakeholders' perceptions of integrated rainwater management approaches in the Blue Nile Basin of the Ethiopian highlands
    Mulema, Annet A. ; Lema, Zelalem ; Assefa, Elias ; Adie, Aberra ; Ogutu, Zadoc ; Duncan, Alan J. - \ 2017
    Natural Resources Forum 41 (2017)4. - ISSN 0165-0203 - p. 244 - 254.
    Ethiopia - Gender - Innovation platforms - Integrated rainwater management - Multi-stakeholders

    Previous approaches to improve soil and water management in the Ethiopian highlands have achieved marginal success. An integrated approach to rainwater management (RWM) has been piloted to address interrelated problems of land degradation, livestock feed shortage, and soil erosion, in an effort to improve the resilience of rural livelihoods. However, stakeholders' perceptions about the approach have not been documented. Using data from in-depth interviews, this study assesses stakeholders' knowledge, attitudes, skills and practices in the Diga, Jeldu and Fogera districts of Ethiopia. Our study finds gender differences in knowledge and application of integrated RWM strategies amongst farmers. Stakeholders interviewed appreciate fodder development because it directly addresses land degradation and livestock feed shortage, and provides extra benefits to the households. There are differences in successful RWM practices across the districts. Planners, researchers and policy makers engaged in innovation platforms have an increased understanding of the tools to engage multiple stakeholders in planning for RWM. However, inflexible extension approaches and other contextual issues limit wide-scale use of bottom-up approaches. We conclude that approaches to RWM that are holistic and engage diverse stakeholders foster the uptake of innovations. Awareness creation, collaboration, capacity development, incentives, monitoring, political will and favorable gender norms are vital to the process.

    Price risk perceptions and management strategies in selected European food supply chains : An exploratory approach
    Assefa, Tsion T. ; Meuwissen, Miranda P.M. ; Oude Lansink, Alfons G.J.M. - \ 2017
    NJAS Wageningen Journal of Life Sciences 80 (2017). - ISSN 1573-5214 - p. 15 - 26.
    European union - Exploratory - Food supply chains - Interviews - Management strategies - Perceptions - Price risk

    Agricultural prices in European food markets have become more volatile over the past decade exposing agribusinesses to risk and uncertainty. This study goes beyond the farm stage and explores through interviews the price risk perceptions and management strategies in multiple stages of the food supply chain. Respondents were farmers, wholesalers, processors, and retailers in six European food supply chains. Results show that price risk management strategies in EU food chains are diverse and well beyond traditional instruments such as futures and forward contracts. We further find that deviations of prices by more than 10–15% from expected levels were perceived as price volatility by a majority of the chain actors. This study provides new insights on price risk management, a deeper understanding of price risk perceptions and highlights the interrelation of price risk management decisions with other business decisions.

    Supermarkten romen prijsschommelingen af
    Assefa, Tsion - \ 2017

    BuAls de voedselprijzen dalen op de consumentenmarkt, vertalen de supermarkten die lagere prijzen onmiddellijk door naar de boeren en tuinders. Maar als de varkens- en groenteprijzen in het begin van de voedselketen dalen door overaanbod, vertalen de supermarkten die meevaller maar ten dele door naar de consumenten. Zo gebruiken de retailers hun marktmacht om meer winst te maken, constateert de Wageningse promovendus

    The transmission and management of price volatility in food supply chains
    Assefa, Tsion Taye - \ 2016
    Wageningen University. Promotor(en): Alfons Oude Lansink, co-promotor(en): Miranda Meuwissen. - Wageningen : Wageningen University - ISBN 9789462579835 - 132
    food prices - agricultural prices - volatility - cap - food - supply chain management - price controls - voedselprijzen - landbouwprijzen - vluchtigheid - gemeenschappelijk landbouwbeleid - voedsel - ketenmanagement - prijsbewaking

    The 2006-2011 period has been marked by increased volatility in food an agricultural commodity prices at a global level. In the EU, the continuous liberalization of agricultural markets under the Common Agricultural Policy has led to the exposure of EU agricultural to increasing market price volatility. This thesis has investigated the transmission and management of price volatility in EU food supply chains. The transmission of price volatility in various food supply chains is first investigated through a literature review followed by an empirical analysis of price volatility transmission in the case of the German fresh pork supply chain. The effect of market power was also taken into account in the latter empirical analysis. Next, the management of price volatility was investigated through interviews conducted with actors of selected EU food supply chains. This was followed by the analysis of the effectiveness of selected price volatility management strategies. Lastly, in light of the policy support for agricultural insurance within the Common agricultural policy, premium rates of an agricultural revenue insurance contract were calculated for the Dutch ware potato sector.

    One of the gaps identified in the reviewed literature is the lack of attention given to the effects of contextual factors on price volatility transmissions in food supply chains. Contextual factors include market power in the chain and pricing strategies (e.g. contracts) by chain actors. Results of the price volatility transmission analysis conducted in this thesis in the case of the German pork chain show that retail market power limited both the transmission of price levels and price volatility. This thesis shows that price volatility is perceived as risky by all actors in the food supply chain. Deviations of prices by more than 10 to 15 % from expected levels were perceived as price volatility by a majority of the chain actors. Results further show that price volatility management strategies in EU food chains are diverse and well beyond traditional instruments such as futures and forward contracts. Contrary to expectations, price fixing contracts were not found to be desirable by interviewed chain actors. This thesis also found that the effectiveness of contracts in reducing price volatility depended on how the contract price was set.

    Results of this thesis further show that premium rates of a revenue insurance contract for the Dutch ware potato sector across categories of farms. The average premium rates calculated were 32.1%, 22.2%, 33.1% and 24.0% on guaranteed revenue per hectare for the high expected yield, low expected yield, high yield variance to expected yield ratio and low yield variance to expected yield ratio categories of farm, respectively. The difference in premium rates across categories of farms implies that charging the same average premium rate to all Dutch ware potato farms can lead to adverse selection.

    Morphological dynamics of gully systems in the subhumid Ethiopian Highlands : the Debre Mawi watershed
    Zegeye, Assefa D. ; Langendoen, Eddy J. ; Stoof, C.R. ; Tilahun, Seifu A. ; Dagnew, Dessalegn C. ; Zimale, Fasikaw A. ; Guzman, C.D. ; Yitaferu, B. ; Steenhuis, T.S. - \ 2016
    SOIL 2 (2016). - ISSN 2199-3971 - p. 443 - 458.
    Gully expansion in the Ethiopian Highlands dissects vital agricultural lands with the eroded materials adversely impacting downstream resources, for example as they accumulate in reservoirs. While gully expansion and rehabilitation have been more extensively researched in the semiarid region of Ethiopia, few studies have been conducted in the (sub)humid region. For that reason, we assessed the severity of gully erosion by measuring the expansion of 13 selected permanent gullies in the subhumid Debre Mawi watershed, 30 km south of Lake Tana, Ethiopia. In addition, the rate of expansion of the entire drainage network in the watershed was determined using 0.5 m resolution aerial imagery from flights in 2005 and 2013. About 0.6 Mt (or 127 t ha−1 yr−1) of soil was lost during this period due to actively expanding gullies. The net gully area in the entire watershed increased more than 4-fold from 4.5 ha in 2005 to 20.4 ha in 2013 (> 3 % of the watershed area), indicating the growing severity of gully erosion and hence land degradation in the watershed. Soil losses were caused by upslope migrating gully heads through a combination of gully head collapse and removal of the failed material by runoff. Collapse of gully banks and retreat of headcuts was most severe in locations where elevated groundwater tables saturated gully heads and banks, destabilizing the soils by decreasing the shear strength. Elevated groundwater tables were therefore the most important cause of gully expansion. Additional factors that strongly relate to bank collapse were the height of the gully head and the size of the drainage area. Soil physical properties (e.g., texture and bulk density) only had minor effects. Conservation practices that address factors controlling erosion are the most effective in protecting gully expansion. These consist of lowering water table and regrading the gully head and sidewalls to reduce the occurrence of gravity-induced mass failures. Planting suitable vegetation on the regraded gully slopes will in addition decrease the risk of bank failure by reducing pore-water pressures and reinforcing the soil. Finally, best management practices that decrease runoff from the catchment will reduce the amount of gully-related sediment loss.
    Gender Analysis in CASCAPE Interventions : Gender-based roles and constraints in agricultural production
    Roo, N. de; Assefa, B. ; Ahmed, A. ; Boka, B. ; Tadesse, M. ; Tariku, J. ; Tekie, H. ; Zelleke, B. ; Spanjer, M. - \ 2016
    Centre for Development Innovation - 60 p.
    Spatial Runoff Estimation and Mapping of Potential Water Harvesting Sites: A GIS and Remote Sensing Perspective, Northwest Ethiopia
    Mekonnen, M.M. ; Melesse, A.M. ; Keesstra, S.D. - \ 2016
    In: Spatial Runoff Estimation and Mapping of Potential Water Harvesting Sites: A GIS and Remote Sensing Perspective, Northwest Ethiopia / Melesse, Assefa M., Abtew, Wossenu, Cham : Springer (Springer Geography ) - ISBN 9783319187860 - p. 565 - 584.
    Freshwater resources scarcity is becoming a limiting factor for development and sustenance in most parts of Ethiopia. The Debre Mewi watershed, in northwest Ethiopia, is one of such areas where the need for supplemental water supply through rainwater harvesting is essential. Suitable water harvesting sites were identified through overlay analysis considering both social and technical parameters, such as land use/land cover, slope gradient, soil texture, flow accumulation and stakeholders’ priority. This was performed with the integration of GIS and remote sensing applications. Knowledge of runoff resulting from rainfall is most important for designing any water harvesting structure. Direct field-level measurement of runoff is always good, but it is time consuming, labour intensive and expensive. In conditions where direct measurement of runoff could not be possible, remote sensing technology and GIS combined with runoff models are proven to be effective. In this study, the remotely sensed satellite data (Quickbird2) provided spatial information on land use/land cover. Precipitation was obtained from the nearest meteorological station, and soil data were acquired form laboratory analysis. The GIS tools were used to store, manipulate and estimate runoff depth, surface storage and runoff volume, applying Soil Conservation Service (SCS) Curve Number (CN) formula. The direct runoff volume estimated using SCS-CN model is 146,697 m3 for the month of August, at Debre Mewi watershed, which covers about 508 ha. The result was compared with measured values, and closer relationship was found. This indicates that there is enough runoff water to be harvested for different uses. Remote sensing was found to be a very important tool in providing input parameters. GIS was also found to be a very important tool in mapping and integrating the different variables, in the process of runoff estimation and suitable water harvesting sites selection.
    A review of the effects of contextual factors on price volatility transmission in food supply chains
    Assefa, T.T. ; Meuwissen, M.P.M. ; Oude Lansink, A.G.J.M. - \ 2016
    In: Agricultural Markets Instability / Garrido, Alberto, Brümmer, Bernhard, M'Barek, Robert, Meuwissen, Miranda, Morales-Opazo, Cristian, Routledge - ISBN 9781138937413 - p. 85 - 97.
    Price volatility perceptions, management strategies, and policy options in EU food supply chains
    Assefa, T.T. ; Meuwissen, M.P.M. ; Oude Lansink, A.G.J.M. - \ 2016
    In: Agricultural Markets Instability / Garrido, Alberto, Brümmer, Bernhard, M'Barek, Robert, Meuwissen, Miranda, Morales-Opazo, Cristian, Routledge - ISBN 9781138937413 - p. 179 - 192.
    Price Volatility Transmission in Food Supply Chains: A Literature Review
    Assefa, T.T. ; Meuwissen, M.P.M. ; Oude Lansink, A.G.J.M. - \ 2015
    Agribusiness 31 (2015)1. - ISSN 0742-4477 - p. 3 - 13.
    multivariate garch approach - rational-expectations - market power - sector - framework - spillover - dynamics - crisis - impact
    This paper reviews the literature on price volatility transmission in vertical food markets. The methods and major findings of the literature are discussed and avenues for future research are suggested. The literature review shows that price volatility is analyzed using a class of univariate and multivariate GARCH models. The reviewed studies conclude that price volatility transmits along food supply chains thereby exposing all chain actors to risk and uncertainty. Extension of the limited sample period, country, product, and chain stages coverage of the current literature are suggested as avenues for future research. A largely ignored aspect in the current literature is the identification and empirical testing of the role of contextual factors on the degree of price volatility transmission.
    An empirical analysis of farm price volatility and price risk management strategies
    Assefa, T.T. ; Kuiper, W.E. ; Meuwissen, M.P.M. - \ 2014
    An empirical analysis of farm price volatility and price risk management strategies
    Assefa, Tsion - \ 2014
    Fungal Planet description sheets: 214–280
    Crous, P.W. ; Shivas, R.G. ; Quaedvlieg, W. ; Bank, M. van der; Zhang, Y. ; Summerell, B.A. ; Guarro, J. ; Wingfield, M.J. ; Wood, A.R. ; Alfenas, A.C. ; Braun, U. ; Cano-Lira, J.F. ; Garcia, D. ; Marin-Felix, Y. ; Alvarado, P. ; Andrade, J.P. ; Armengol, J. ; Assefa, A. ; Breeÿen, A. den; Camele, I. ; Cheewangkoon, R. ; Souza, J.T. De; Duong, T.A. ; Esteve-Raventós, F. ; Fournier, J. ; Frisullo, S. ; García-Jiménez, J. ; Gardiennet, A. ; Gené, J. ; Hernández-Restrepo, M. ; Hirooka, Y. ; Hospenthal, D.R. ; King, A. ; Lechat, C. ; Lombard, L. ; Mang, S.M. ; Marbach, P.A.S. ; Marincowitz, S. ; Montaño-Mata, N.J. ; Moreno, G. ; Perez, C.A. ; Pérez Sierra, A.M. ; Robertson, J.L. ; Roux, J. ; Rubio, E. ; Schumacher, R.K. ; Stchigel, A.M. ; Sutton, D.A. ; Tan, Y.P. ; Thompson, E.H. ; Vanderlinde, E. ; Walker, A.K. ; Walker, D.M. ; Wickes, B.L. ; Wong, P.T.W. ; Groenewald, J.Z. - \ 2014
    Persoonia 32 (2014). - ISSN 0031-5850 - p. 184 - 306.
    sp-nov - phylogeny reveals - eucalyptus-microfungi - host-associations - gene phylogeny - sequence data - diaporthales - morphology - gnomoniaceae - conioscypha
    Novel species of microfungi described in the present study include the following from South Africa: Cercosporella dolichandrae from Dolichandra unguiscati, Seiridium podocarpi from Podocarpus latifolius, Pseudocercospora parapseudarthriae from Pseudarthria hookeri, Neodevriesia coryneliae from Corynelia uberata on leaves of Afrocarpus falcatus, Ramichloridium eucleae from Euclea undulata and Stachybotrys aloeticola from Aloe sp. (South Africa), as novel member of the Stachybotriaceae fam. nov. Several species were also described from Zambia, and these include Chaetomella zambiensis on unknown Fabaceae, Schizoparme pseudogranati from Terminalia stuhlmannii, Diaporthe isoberliniae from Isoberlinia angolensis, Peyronellaea combreti from Combretum mossambiciensis, Zasmidium rothmanniae and Phaeococcomyces rothmanniae from Rothmannia engleriana, Diaporthe vangueriae from Vangueria infausta and Diaporthe parapterocarpi from Pterocarpus brenanii. Novel species from the Netherlands include: Stagonospora trichophoricola, Keissleriella trichophoricola and Dinemasporium trichophoricola from Trichophorum cespitosum, Phaeosphaeria poae, Keissleriella poagena, Phaeosphaeria poagena, Parastagonospora poagena and Pyrenochaetopsis poae from Poa sp., Septoriella oudemansii from Phragmites australis and Dendryphion europaeum from Hedera helix (Germany) and Heracleum sphondylium (the Netherlands). Novel species from Australia include: Anungitea eucalyptorum from Eucalyptus leaf litter, Beltraniopsis neolitseae and Acrodontium neolitseae from Neolitsea australiensis, Beltraniella endiandrae from Endiandra introrsa, Phaeophleospora parsoniae from Parsonia straminea, Penicillifer martinii from Cynodon dactylon, Ochroconis macrozamiae from Macrozamia leaf litter, Triposporium cycadicola, Circinotrichum cycadis, Cladosporium cycadicola and Acrocalymma cycadis from Cycas spp. Furthermore, Vermiculariopsiella dichapetali is described from Dichapetalum rhodesicum (Botswana), Marasmius vladimirii from leaf litter (India), Ophiognomonia acadiensis from Picea rubens (Canada), Setophoma vernoniae from Vernonia polyanthes and Penicillium restingae from soil (Brazil), Pseudolachnella guaviyunis from Myrcianthes pungens (Uruguay) and Pseudocercospora neriicola from Nerium oleander (Italy). Novelties from Spain include: Dendryphiella eucalyptorum from Eucalyptus globulus, Conioscypha minutispora from dead wood, Diplogelasinospora moalensis and Pseudoneurospora canariensis from soil and Inocybe lanatopurpurea from reforested woodland of Pinus spp. Novelties from France include: Kellermania triseptata from Agave angustifolia, Zetiasplozna acaciae from Acacia melanoxylon, Pyrenochaeta pinicola from Pinus sp. and Pseudonectria rusci from Ruscus aculeatus. New species from China include: Dematiocladium celtidicola from Celtis bungeana, Beltrania pseudorhombica, Chaetopsina beijingensis and Toxicocladosporium pini from Pinus spp. and Setophaeosphaeria badalingensis from Hemerocallis fulva. Novel genera of Ascomycetes include Alfaria from Cyperus esculentus (Spain), Rinaldiella from a contaminated human lesion (Georgia), Hyalocladosporiella from Tectona grandis (Brazil), Pseudoacremonium from Saccharum spontaneum and Melnikomyces from leaf litter (Vietnam), Annellosympodiella from Juniperus procera (Ethiopia), Neoceratosperma from Eucalyptus leaves (Thailand), Ramopenidiella from Cycas calcicola (Australia), Cephalotrichiella from air in the Netherlands, Neocamarosporium from Mesembryanthemum sp. and Acervuloseptoria from Ziziphus mucronata (South Africa) and Setophaeosphaeria from Hemerocallis fulva (China). Several novel combinations are also introduced, namely for Phaeosphaeria setosa as Setophaeosphaeria setosa, Phoma heteroderae as Peyronellaea heteroderae and Phyllosticta maydis as Peyronellaea maydis. Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.
    The effect of Farmer Market Power on the Degree of Farm-Retail Price Transmission: A simulation Model with an Application to the Dutch Ware Potato Supply Chain
    Assefa, T.T. ; Kuiper, W.E. ; Meuwissen, M.P.M. - \ 2014
    Agribusiness 30 (2014)4. - ISSN 0742-4477 - p. 424 - 437.
    sector - lamb - beef
    Aclassic oligopoly/oligopsony model is developed to assess the degree of price transmission in a two-stage farmer–retailer supply chain. A simulation experiment based on data of the Dutch ware potato sector illustrates how price transmission may become imperfect and asymmetric as a consequence of retailer oligopsony power in the sense that farmprice decreases are only partially passed on to consumers whereas farm price increases are more than fully transmitted. Oligopoly power by farmers to level their bargaining power vis-`a-vis the retailers may even make the degree of price transmission worse
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