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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    First report of Neofabraea kienholzii causing bull’s eye rot on pear (Pyrus communis) in the Netherlands
    Wenneker, M. ; Pham, K.T.K. ; Boekhoudt, L.C. ; Boer, F.A. de; Leeuwen, P.J. van; Hollinger, T.C. ; Thomma, B.P.H.J. - \ 2017
    Plant Disease 101 (2017)4. - ISSN 0191-2917 - p. 634 - 634.

    Pear (Pyrus communis L.) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014, and ‘Conference’ is the main cultivar. In the Netherlands, pears are kept in controlled atmosphere cold storage up to 11 months after harvest. Symptoms of bull’s eye rot were observed in 2015 on ‘Conference’ pears in storage in the Netherlands. Bull’s eye lesions on apple and pear fruits are generally caused by four Neofabraea species: N. alba Jacks, N. malicorticis Guthrie, N. perennans Kienholz, and N. kienholzii Seifert, Spotts & Lévesque (Gariepy et al. 2005). N. alba is the major pathogen causing bull’s eye rot on pear fruits in the Netherlands. Independent of the species, the symptoms appear as flat or slightly sunken lesions, which are brown, often lighter brown in the center (Spotts et al. 2009). To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). PDA plates were incubated at 20°C in the dark, and single spores were transferred to fresh PDA plates. The isolates produced colonies with white-yellowish to brownish mycelium. Microconidia were produced on feathery fascicles of aerial mycelium, with a white, powdery, or sugary appearance on the surface of the agar colony. Microconidia were 2.5 to 6.5 × 1.5 to 2.5 µm, ellipsoidal, slightly asymmetrical to a curved form. The identity of a representative isolate (PPO 45010) was confirmed by means of multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin) in combination with the Kingfisher method (Waltham, MA). Segments of the internal transcribed spacer region (ITS), 28S ribosomal RNA (28S rRNA) and beta-tubulin (TUB2) loci were amplified, sequenced with primers ITS1/ITS4, LR0R/LR5, and Btub2Fd/Btub4Rd (Chen et al. 2016), and deposited in GenBank under accession nos. KX424942 (ITS), KX424941 (28S rRNA), and KX424940 (TUB2). MegaBLAST analysis revealed that the ITS, 28S rRNA, and TUB2 sequences matched with 99 to 100% identity to N. kienholzii isolates in GenBank (KR859082 and KR859083 [ITS], KR858873 and KR858874 [28S rRNA], KR859288 and KR859289 [TUB2]). Alcohol surface sterilized fruits were inoculated in pathogenicity tests in two ways: (i) with an agar disk (10 mm diameter) with actively growing mycelium of N. kienholzii prepared from a 14-day-old culture grown on PDA; and (ii) with 20 μl of a spore suspension (105 conidia ml-1) prepared from a 21-day-old PDA culture after wounding with a needle. Both experiments were performed on 10 ‘Conference’ pears. Inoculated fruits were sealed in plastic bags and were incubated in darkness at 20°C. Typical symptoms appeared between 7 and 14 days. Mock-inoculated controls with water and PDA-only controls remained symptomless. Fungi isolated from the lesions had morphological characteristics that resembled the original isolates from infected pears. The identity of these isolates was confirmed as N. kienholzii by sequencing, thus completing Koch’s postulates. Bull’s eye rot of apple and pear is an important postharvest disease, occurring in major fruit growing areas of North America, Chile, Australia, and Europe (Henriquez et al. 2004; Spotts et al. 2009). N. kienholzii was reported twice on apple in Europe (Michalecka et al. 2016). To the best of our knowledge, this is the first report of N. kienholzii causing bull’s eye rot of pear in Europe.

    First report of Truncatella Angustata causing postharvest rot on ‘topaz’ apples in the Netherlands
    Wenneker, M. ; Pham, K.T.K. ; Boekhoudt, L.C. ; Boer, F.A. de; Leeuwen, P.J. van; Hollinger, T.C. ; Thomma, B.P.H.J. - \ 2017
    Plant Disease 101 (2017)3. - ISSN 0191-2917 - p. 508 - 508.

    In the Netherlands, about 30% of the organic apple (Malus domestica Borkh.) production consists of apple scab resistant cultivars, such as Topaz and Santana. However, organic ‘Topaz’ apples show a high incidence of fungal rot after storage. Hot-water treatment (HWT) of freshly harvested apple fruit prior to long-term storage is an important strategy for the control of postharvest diseases, especially in the organic production sector (Maxin et al. 2012). The recommended treatment temperatures and times vary according to the cultivar because of the risk of heat damage to the fruit peel. In January 2016, light peel damage caused by HWT was observed on ‘Topaz’ apples from an organic orchard. Also, up to 15% of the ‘Topaz’ apples showed typical rot lesions of an unknown causal agent. The lesions showed brown, irregular necrosis and were slightly sunken. To isolate the causal agent, fruits were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single spore isolates were transferred to fresh PDA plates. The colonies that appeared on PDA were cottony to woolly, dull white to brown in color, with black acervuli mainly in the center of the PDA plates. The isolates produced four-celled conidia, 16 to 19 × 7 to 9 µm, straight to slightly curved, with two brown to dark-brown median cells that had thick walls. More than one hyaline apical appendage, variable in size and branched dichotomically, were observed and a basal appendage was absent. The fungus was morphologically identical to Truncatella angustata (Pers.) S. Hughes (Sutton 1980). The identity of two representative isolates (PPO-45246 and PPO-45321) was confirmed by means of gene sequencing. To this end, DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, MA). Sequences of the ITS region were amplified using primers ITS1/ITS4, sequenced, and deposited in GenBank under accession numbers KX085227 and KX085228. MegaBLAST analysis revealed that both of our ITS sequences matched 99% with T. angustata isolates in GenBank (EU342216, JX390614, and KF646105). Koch’s postulates were fulfilled using 10 ‘Topaz’ apples. Surface sterilized fruits were inoculated with 20 μl of 105 conidiospores ml–1 in water, prepared from a 15-day-old PDA culture of the isolate PPO-45246, after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. Symptoms appeared after 7 days on 100% of the fruits while mock-inoculated controls with water remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the inoculated isolates. The identity of the reisolations was confirmed as T. angustata by sequencing. T. angustata has a worldwide distribution and has also been reported to cause leaf spot on Rosa canina (Eken et al. 2009), canker and twig dieback on blueberry (Vaccinium spp.) (Espinoza et al. 2008), and fruit rot of olive (Olea europaea) (Arzanlou et al. 2012). To the best of our knowledge, this is the first report of T. angustata causing fruit rot of apples. Importantly, we note that the occurrence of this fruit rot may be enhanced by wounding, in this case as a result of hot water treatment.

    First Report of Neonectria candida Causing Postharvest Decay on ‘Conference’ Pears in the Netherlands
    Wenneker, M. ; Pham, K.T.K. ; Lemmers, M.E.C. ; Boer, F.A. De; Lans, A.M. Van Der; Leeuwen, P.J. Van; Hollinger, T.C. ; Thomma, B.P.H.J. - \ 2016
    Plant Disease 100 (2016)8. - ISSN 0191-2917 - p. 1787 - 1787.
    Pear (Pyrus communis) is an important fruit crop in the Netherlands, with a total production of 349,000 tons in 2014, and ‘Conference’ is the main pear cultivar that occupies 75% of the total pear production area. In the Netherlands, pears are kept in controlled atmosphere cold storage up to 11 months after harvest. Occasionally, storage rots are observed when storage crates are contaminated with orchard soil. In a storage trial (2012 to 2013), boxes with ‘Conference’ pears were amended with soil particles from the same orchard from which the pears were harvested (four orchards), and stored for 11 months. Boxes without amended soil were included as controls. In contrast to the control boxes, up to 15% of the pears stored in boxes with soil particles showed typical rot symptoms (lesions) of an unknown causal agent. The lesions showed brown and watery circular necrosis, were slightly sunken, and displayed whitish to yellowish mycelia covering the lesions. To isolate the causal agent, fruit were rinsed with sterile water, lesions were sprayed with 70% ethanol until droplet runoff, the skin was removed aseptically with a scalpel, and tissue under the lesion was isolated and placed onto potato dextrose agar (PDA). The PDA plates were incubated at 20°C in the dark, and single spore isolates were transferred to fresh PDA plates. These isolates produced fast-growing colonies with white-yellowish mycelium. Conidia were hyaline, cylindrical, 1 to 3 septate, and 15.8 to 26.4 × 5.3 to 7.9 µm. The fungus was morphologically identical to Neonectria candida (syn. N. ramulariae; anamorph Cylindrocarpon obtusiusculum) (Lombard et al. 2015). The identity of a representative isolate (VTN10Bs3) was confirmed by means of multilocus gene sequencing. To this end, genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, USA). Sequences of the ITS region, translation elongation factor 1-alpha (TEF1), and actin (ACT2) loci were amplified, sequenced, and deposited in GenBank under accessions KU588183 (ITS), KU588186 (TEF1), and KU588184 (ACT2). MegaBLAST analysis revealed that our ITS, TEF1, and ACT2 sequences matched with >99 to 100% identity to N. candida isolates in GenBank (KM249079 and JF735314 [ITS], JF735791 and HM054091 [TEF1], and KM231146 [ACT2]). Subsequently, Koch’s postulates were performed on 15 ‘Conference’ pears. Surface sterilized fruits were inoculated with 20 µl of a suspension of 105 conidiospores ml–1 water, prepared from a 15-day-old PDA culture, after wounding with a needle. Inoculated fruits were sealed in a plastic bag and incubated in darkness at 20°C. Symptoms appeared after 7 days on 100% of the fruits while mock-inoculated controls with water remained symptomless. Fungal colonies isolated from the lesions and cultured on PDA morphologically resembled the original isolate from the infected pears. Moreover, symptoms observed on artificially inoculated ‘Conference’ pear fruit were identical to the decay observed on ‘Conference’ pears that were obtained from the cold storage experiment. The identity of the reisolations was confirmed as N. candida by sequencing. N. candida (syn. N. ramulariae) is known as a globally distributed soilborne fungus (Domsch et al. 2007), but only few studies have identified the fungus as plant pathogen (Hirooka 2012). This is the first report of N. candida causing storage rot of pears. Importantly, we note that the occurrence of storage rots may be enhanced by contamination of storage crates or fruit with orchard soil.
    Baseflow prediction in a data-scarce catchment with Inselberg topography, Central Mozambique
    Weemstra, H. ; Oord, A.L. ; Boer, F.S. de; Beekman, P.W. - \ 2014
    Physics and Chemistry of the Earth 76-78 (2014). - ISSN 1474-7065 - p. 16 - 27.
    Baseflow - Differential gauging - Rainfall-runoff model - Smallholder irrigation - Ungauged drainage basin - Water balance

    This study aimed to improve the understanding of hydrological processes in a humid (sub)tropical area in Africa with Inselberg topography. Additionally, the study intended to develop an approach for selective discharge data acquisition to determine water availability for smallholder irrigation in similar data-scarce catchments. During the December 2012-August 2013 field campaign meteorological and river stage data were collected at the Messica catchment in Central Mozambique. The 220km2 catchment has an estimated 1000ha of irrigated land, developed by smallholder farmers. Baseflow in the perennial tributary streams on the slopes of a meta-sedimentary Inselberg is the source of irrigation water. The baseflow recession curve of one of these tributaries is analysed and the water balance of an average year was determined. Precipitation, potential evapotranspiration, actual evapotranspiration and discharge were estimated to be 1224, 1462, 949 and 266mm/year respectively. Differential gauging showed that the perennial tributaries gain water; the groundwater contribution increased with approximately 50% over two and a half month relative to the downstream discharge from March to May. In the downstream parts the groundwater contribution per metre stream length is between 30% and 100% higher compared to the upstream parts for two of the tributaries. Nevertheless, due to natural streambed infiltration and irrigation canals, discharge varies over the length of these tributaries. A rainfall-runoff model (HBV) was calibrated using the field data to examine the relation between precipitation characteristics and discharge at the start of the dry season. For precipitation scenarios with low and high intensity precipitation, discharges from June onwards were approximately similar in size according to the calibrated model. This suggest that discharge at the start of the dry season is mainly determined by total precipitation and the timing of precipitation (i.e. early or late in the wet season), not by individual rainfall events or rainfall intensity. It is concluded that the use of selective discharge measurements and low frequency precipitation measurements can effectively be used for water availability assessments in Inselberg catchments. Further research should be conducted to verify the validity of the used techniques in other humid sub-tropical Inselberg areas.

    Integrated Food and Nutrition Security Programming to Address Undernutrition : The Plan Approach
    Boer, F.A. de; Verdonk, I. - \ 2012
    Wageningen : Wageningen UR Centre for Development Innovation (Report / Wageningen UR Centre for Development Innovation CDI-12-014) - 34
    voedselzekerheid - slechte voeding - honger - ondervoeding - food security - malnutrition - hunger - undernutrition
    From a technical point of view, it is widely recognised that an integrated approach to food and nutrition security is an effective way to promote child nutritional well-being. In this desk review, based on project documents of the countries which took part in the PLAN NL supported Food and Nutrition Security Support Programme (FNSSP), what kind of interventions were undertaken and their strengths and weaknesses are compared with the lessons learned from the World Bank. Report number CDI-12-014.
    Vegetable Chains and Consumption in the Nairobi Metropolis: Report on a stakeholder workshop November 21, 2011
    Lans, C.J.M. van der; Boer, F.A. de; Elings, A. - \ 2012
    Bleiswij : Wageningen UR Greenhouse Horticulture (Rapporten WUR GTB 1129) - 32
    Vegetable chains in Kenya: Production and consumption of vegetables in the Nairobi metropolis
    Lans, C.J.M. van der; Snoek, H.M. ; Boer, F.A. de; Elings, A. - \ 2012
    Bleiswijk : Wageningen UR Greenhouse Horticulture (Rapporten WUR GTB 1130) - 86
    voedselconsumptie - consumptiepatronen - groenten - analyse - internationale samenwerking - stedelijke bevolking - afrika - kenya - food consumption - consumption patterns - vegetables - analysis - international cooperation - urban population - africa
    Vegetable consumption in African countries such as Kenya is low, which has a negative impact on the nutritional condition of the population, and on the production by smallholders. The goals of the project were to determine the potentials for consumption and cultivation in the Nairobi metropolitan region, to analyse the reasons for low consumption and to define strategies to stimulate consumption and production. Vegetable consumption can be increased, especially during the dry season when availability is low, and for low-income groups. Production can be increased through technical interventions and improvement of skills. Important is to improve the leverage of producers in the value chain and the efficiency of the value chain. Key elements are: stimulate urban farming; reduce the cost price throughout the value chain and make the value chain more transparent, accountable, shorter with less transaction costs; reduce post-harvest losses, develop a revenue system that better rewards farmers; improve cold storage and logistics, improve irrigation in the dry season; offer dry-season solutions through food processing; and pay attention to a number of life-style issues. The Netherlands can contribute in the fields of re-structuring the value chain, brokering between parties, food processing, consumer behaviour, production and product quality (irrigation, quality seeds, crop management), and R&D.
    Report of the workshop on MSP and Transitions CDI & WLR : 7-9 February 2011, De Bosrand, Ede
    Vugt, S.M. van; Boer, F.A. de; Bos, A.P. - \ 2011
    Wageningen : Wageningen UR Centre for Development Innovation - 44
    WLR and CDI organised in 2011 a training on MSP and Transitions in order to deepen each other’s knowledge and share the ideas underlying the change processes they work in. The training was divided in two parts with the focus on MSP framework, Process model, Power and Conflict and Transitions in the first part. The second part was more devoted to the Theories of Change, the actual stakeholder management and the M&E of these change processes.
    Plan's CCCD approach - Country study PLAN-Kenya
    Boer, F.A. de - \ 2009
    Wageningen : Wageningen UR Centre for Development Innovation - 38
    The field study for Kenya, a part of the strategic formative evaluation on CCCD, was carried out August 16-23, 2009. This country study aimed at studying CCCD as an approach for development and how it was applied by Plan Kenya. The executive summary covers the main findings and recommendations of the field study in Kenya. Detailed findings and recommendations concerning Plan Kenya are described in this report. Findings and recommendations when relevant are incorporated in the synthesis report: Strategic Evaluation Study on CCCD for Plan NLNO. After the introduction the report starts with an overview on the country context and Plan Kenya. The third chapter presents how Plan staff and partners view CCCD, fourth chapter is on how CCCD works in practice, chapter 5 looks in more detail on partnerships. The report ends with a summary of the findings and recommendations. CCCD was introduced in Kenya in 2004. Programmes undertaken by Plan Kenya do take child centredness and community development as their main point of departure.
    Strategic evaluation study on child-centred community development - Synthesis report
    Brouwer, J.H. ; Boer, F.A. de; Uffelen, G.J. van; Wigboldus, S.A. - \ 2009
    Wageningen : Wageningen UR Centre for Development Innovation - 75
    This strategic formative evaluation was carried out by Wageningen International Capacity Development & Institutional Change (CD&IC) programme from May to September 2009. The evaluation aims to obtain insight into the understanding of CCCD within Plan, and to learn more about the factors that favour or obstruct the implementation of Child Centred Community Development (CCCD) in practice. Suggestions on improving CCCD as an approach to development are provided, as well as an analysis of capacity development needs for CCCD implementation. This evaluation report is a product of Phase I of the complete anticipated evaluation trajectory. Phase II will most likely include an international workshop around the findings of Phase I. The findings of Phase I will contribute to the track record for the MFS II application to the Dutch Ministry of Foreign Affairs which Plan Netherlands is currently preparing. The study comprised a desk research stage, which reviewed relevant Plan documentation as well as consultations with key stakeholders within Plan worldwide. During this stage face to face interviews were conducted in Plan IH office in Woking, and at NLNO in Amsterdam. Other interviews with stakeholders in ROs and NOs were done using Skype. Furthermore two field studies were conducted in Kenya and Bangladesh. Given the fact that the topic of the study is broad, it is limited to analysis of the wider issues pertaining to CCCD rather than in-depth detailed analysis of these issues.
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