Wopke Van der Werf

Wopke Van der Werf
Wageningen University & Research | WUR · Faculty of Plant Sciences

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815
Publications
158,844
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12,398
Citations
Additional affiliations
January 1984 - December 2014
Wageningen University & Research
Position
  • Professor (Associate)

Publications

Publications (815)
Article
Crop diseases may be affected by landscape composition, but limited quantitative information is available. We studied the effects of landscape factors on the incidence of the psyllid-transmitted bacterium Candidatus Liberibacter solanacearum (CLso) haplotype C in carrots in Finland. Samples were collected from 104 carrot fields in 2013 and 2014. Th...
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Intercropping increases resource capture due to species complementarities, but it is not clear to which extent intercropping also affects the redistribution of carbohydrates and nitrogen (N) within the plant. Here, we examined in two years field experimentation the accumulation and translocation of dry matter and N in maize and peanut in pure stand...
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CONTEXT Sustainable cropping systems need to balance productivity and profitability with resource and environmental conservation. Within a population of cropping system observations, there might be positive deviants that outperform others in terms of sustainability, which could serve as “model systems” for future development. Wheat-maize double cro...
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The EFSA Panel on Plant Health performed a pest categorisation of Dendrolimus superans Butler (Lepidoptera: Lasiocampidae), the larch caterpillar, for the EU territory. D. superans is a major pest of conifer forests in Japan, northeast China and non-European Russia. However, reports of damage are to conifer species not grown in EU forestry. Larix g...
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The EFSA Panel on Plant Health performed a pest categorisation of Pulvinaria psidii (Hemiptera: Coccidae), the green shield scale, for the EU. P. psidii was originally described from Hawaii on Psidium sp. and it is now established in many countries in tropical and subtropical regions of the world. Within the EU, the pest has been reported from main...
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The EFSA Plant Health Panel performed a pest categorisation of Colletotrichum aenigma, C. alienum, C. perseae, C. siamense and C. theobromicola, five clearly defined fungi of the C. gloeosporioides complex causing anthracnose. The pathogens are widely distributed in at least three continents. C. aenigma and C. siamense are reported from Italy and C...
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Apple is one of the most widely cultivated fruit crops worldwide, and apple yield benefits from pollination by insects. The global decline in wild pollinator populations raises concern about the adequacy of pollination services in apple production. Here, we present a global meta‐analysis of pollination in apple. We assembled from the literature a d...
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Organic farming supports higher biodiversity than conventional farming, but at the cost of lower yields. We conducted a meta‐analysis quantifying the trade‐off between biodiversity and yield, comparing conventional and organic farming. We developed a compatibility index to assess whether biodiversity gains from organic farming exceed yield losses,...
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Pollination deficits can compromise fruit yield and quality and have been reported in several fruit crops. It is unknown whether there is a pollination deficit in the production of Korla fragrant pear, Pyrus sinkiangensis, in China, and if so, whether this deficit can be mitigated by the use of managed honeybees (Apis mellifera). We assessed insect...
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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by plants of Prunus domestica grafted on Prunus cerasife...
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Mutation rates are of key importance for understanding evolutionary processes and predicting their outcomes. Empirical mutation rate estimates are available for a number of RNA viruses, but few are available for DNA viruses, which tend to have larger genomes. Whilst some viruses have very high mutation rates, lower mutation rates are expected for v...
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Intercropping maize and soybean is renowned for improving crop production and resource use efficiencies. Interspecific competition and complementarity with respect to root plasticity is essential knowledge for understanding the mechanisms of overyielding and optimizing intercropping species selection. We conducted a three-year field experiment (201...
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The EFSA Panel on Plant Health performed a pest categorisation of Russellaspis pustulans (Hemiptera: Asterolecaniidae), the oleander pit scale, for the EU. R. pustulans occurs widely in tropical and subtropical areas of the world and is restricted to indoor plantings in cooler temperate regions. Within the EU, it has been reported in some literatur...
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The EFSA Panel on Plant Health performed a pest categorisation of Oligonychus perseae (Acari: Prostigmata: Tetranychidae), the persea mite, for the EU. O. perseae is a tropical species that originated in Mesoamerica and has now spread and established in California, Florida, Hawaii, Morocco, southern Europe and Israel. Within the EU, it is establish...
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The EFSA Panel on Plant Health conducted a pest categorisation of Capsicum chlorosis virus (CaCV) for the EU territory. The identity of CaCV, a member of the genus Orthotospovirus (family Tospoviridae), is established and reliable detection and identification methods are available. The pathogen is not included in the EU Commission Implementing Regu...
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Abstract The EFSA Panel on Plant Health performed a pest categorisation of Tetraleurodes perseae (Hemiptera: Aleyrodidae), the red‐banded whitefly, for the territory of the EU. T. perseae is a tropical and subtropical species that originated in the Neotropical region and has now spread and established in the USA (California and Florida), Israel and...
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The EFSA Panel on Plant Health performed a pest categorisation of Platypus apicalis (Coleoptera: Curculionidae: Platypodinae), an ambrosia beetle, also known as a pinhole borer, for the EU territory. P. apicalis is a polyphagous pest native to New Zealand. The majority of its life cycle is spent inside tree wood, but it does not directly feed on pl...
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Abstract The EFSA Panel on Plant Health performed the pest categorisation of the ulluco weevil, Amathynetoides nitidiventris (Hustache), for the EU territory. This species is not included in EU Commission Implementing Regulation 2019/2072. However, its only substantiated host, ulluco (Ullucus tuberosus), is included in Annex I of Regulation EU 2018...
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Abstract The EFSA Plant Health Panel performed a pest categorisation of Fusarium pseudograminearum O'Donnell & T. Aoki. F. pseudograminearum is a soil‐borne fungal pathogen, able to cause a disease known as Fusarium crown rot (FCR, also known as foot and root rot) and occasionally Fusarium head blight on small grain cereals, particularly Triticum a...
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Abstract The EFSA Panel on Plant Health performed a pest categorisation of Atalodera andina (Nematoda: Heteroderidae) for the European Union (EU) territory. A. andina belongs to the order Rhabditida, subfamily Ataloderinae. This species has not been reported from the EU. It is not included in the EU Commission Implementing Regulation 2019/2072. It...
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Abstract The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in the Commission Implementing Regulation (EU) 2018/2019 as ‘High‐risk plants, plant products and other objects’. This Scientific Opinion covers plant health risks posed by potted plants (2–3 years old) of Berberi...
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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation EU/2018/2019 as 'High risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by unrooted cuttings of Jasminum polyanthum that are impor...
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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by dormant grafted plants, rootstocks, budwood and scion...
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The EFSA Panel on Plant Health performed a pest categorisation of Aulacaspis tubercularis (Hemiptera: Diaspididae), the white mango scale, for the EU. A. tubercularis is a tropical species that originates from Asia but is now established in several tropical and subtropical regions throughout the world. It also occurs within the EU and is establishe...
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The EFSA Panel on Plant Health conducted a pest categorisation of High Plains wheat mosaic virus (HPWMoV) for the EU territory. The identity of HPWMoV, a member of the genus Emaravirus (family Fimoviridae), is well established and reliable identification methods are available. The pathogen is not included in the EU Commission Implementing Regulatio...
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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by 2-year-old bare rooted plants for planting of Acer pa...
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Plant species have different traits for mobilizing sparingly soluble phosphorus (P) resources, which could potentially lead to overyielding in P uptake by plant species mixtures compared to monocultures due to higher P uptake as a result of resource (P) partitioning and facilitation. However, there is circumstantial evidence at best for overyieldin...
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Cropping system diversification through annual intercropping provides a pathway for agricultural production with reduced inputs of fertilizer and pesticides. While several studies have shown that intercrop performance depends on the genotypes used, the available evidence has not been synthesized in an overarching analysis. Here, we review the effec...
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Intercropping has frequently been reported to provide good weed suppression. Here, we tested the hypothesis that the weed biomass in annual intercropping systems can be adequately forecasted based on the weed biomass obtained in pure stands of the component crop species. The aim of this analysis was to enlarge the understanding on the weed suppress...
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The EFSA Panel on Plant Health performed a pest categorisation of Zaprionus indianus (Diptera: Drosophilidae), the African fig fly for the territory of the EU. This species successfully colonised the Indian subcontinent more than four decades ago, and more recently South and North America. Within the EU, the pest occurs in Cyprus, Malta, Portugal (...
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The EFSA Panel on Plant Health performed a pest categorisation of Toumeyella parvicornis (Cockerell) (Hemiptera: Coccidae) for the EU territory. This species is not included in EU Commission Implementing Regulation 2019/2072. T. parvicornis is a soft-scale insect native to North America and has been introduced to the Caribbean region and the EU. It...
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The EFSA Panel on Plant Health performed a pest categorisation of Pseudococcus cryptus Hempel (Hemiptera: Pseudococcidae), the citriculus mealybug, for the EU. P. cryptus originates from Southeast Asia but is now established in East Africa, the Middle East and South America. The pest is not currently known to occur in the EU (there was a record onc...
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The EFSA Panel on Plant Health performed a pest categorisation of Plicosepalus acaciae (Zuccarini) Wiens & Polhill), the acacia strap flower, a hemiparasitic plant of the family Loranthaceae parasitising woody plants. Host plants include several species of the genera Vachellia, Tamarix and Ziziphus and various fruit crops. P. acaciae is present in...
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Abstract The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. This Scientific Opinion covers plant health risks posed by defoliated and in dormant phase, grafted bar...
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The EFSA Panel on Plant Health performed a pest categorisation of Sirex nitobei (Hymenoptera: Siricidae), the nitobe horntail, for the territory of the EU. S. nitobei is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072 but was identified as a potential regulated pest in a commodity risk assessment of Pinus thunbergii arti...
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Abstract The European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae), commonly known as the forest tent caterpillar, for the territory of the EU. M. disstria is a North American polyphagous leaf‐eating pest primarily feeding on deciduous trees belonging...
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There is increasing demand for farmers to reduce their use of anthropogenic inputs such as fertilizers and pesticides. It is often suggested that nature offers alternative ways to suppress pests, but what might these be? One prominent difference between most natural and agricultural systems is the diversity of plants and associated biota such as ar...
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The EFSA Panel on Plant Health performed a pest categorisation of Thecodiplosis japonensis (Diptera: Cecidomyiidae) for the EU territory. This species is not included in the EU Commission Implementing Regulation 2019/2072. T. japonensis Uchida & Inouye is a well-defined species, native to a large part of Japan, which was introduced to the Republic...
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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver a scientific opinion on the risk posed by bonsai plants from China consisting of Pinus parviflora grafted on Pinus thunbergii taking into account the available scientific information, including the technical information provided by China. All pests associated wi...
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The EFSA Panel on Plant Health performed a pest categorisation of Bagrada hilaris (Hemiptera: Pentatomidae) for the EU territory. B. hilaris, known as the bagrada bug or painted bug, is a polyphagous pest feeding on at least 25 plant families including several economically important brassica crops such as broccoli, cabbage and cauliflower. Other ec...
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The EFSA Plant Health Panel performed a pest categorisation of Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), an ascomycete fungus causing Fusarium wilt (Panama disease) on Musa spp. Foc TR4 is pathogenic to the commercial banana varieties including those of the 'Cavendish' group and is considered as the most destructive among Foc hap...
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Following a request from the EU Commission, the EFSA Panel on Plant Health conducted a pest categorisation of Apium virus Y (ApVY) for the EU territory. The identity of the ApVY, a member of the genus Potyvirus (family Potyviridae), is well established and reliable detection methods are available. The pathogen is not included in EU Commission Imple...
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Insecticide use and landscape context are major drivers for the abundance of beneficial arthropods, such as predators, parasitoids and pollinators. However, the relative importance of local and landscape‐wide insecticide use is not well understood, and it is unclear to what extent impacts of insecticides on beneficial arthropod populations are mode...
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The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in the Commission Implementing Regulation (EU) 2018/2019 as 'High-risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by potted plants (2-4 years old) of specified Lonice...
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The EFSA Panel on Plant Health performed a pest categorisation of Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), the pink hibiscus mealybug, for the EU. M. hirsutus is native to Southern Asia and has established in many countries in tropical and subtropical regions throughout the world. Within the EU, the pest has been reported from Cyprus a...
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The EFSA Panel on Plant Health performed a pest categorisation of the Japanese grape leafhopper, Arboridia kakogawana (Matsumura, 1932) (Hemiptera: Cicadellidae), for the EU territory. This species is not included in the EU Commission Implementing Regulation 2019/2072. Adults of A. kakogawana overwinter in broad-leaved and mixed forests and move to...
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p>Intercropping has been advocated as an environmentally benign method to suppress weeds in agriculture. However, it is not evident from the literature what size of weed suppressive effect is achieved on average by intercropping, and how species choice and crop management affect this effect. We conducted a global meta-analysis of published data to...
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Abstract Following a request from the EU Commission, the EFSA Panel on Plant Health conducted a pest categorisation of carrot thin leaf virus (CTLV) for the EU territory. The identity of CTLV, a member of the genus Potyvirus (family Potyviridae), is well established and reliable detection methods are available. The pathogen is not included in the E...
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Abstract The EFSA Plant Health Panel performed a pest categorisation of Xanthomonas citri pv. viticola (Nayudu) Dye, a Gram‐negative bacterium belonging to the Xanthomonadaceae family. The pathogen is a well‐defined taxonomic unit and is the causal agent of the leaf spot and bacterial canker of Vitis vinifera. This bacterium is present in India and...
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Abstract The EFSA Panel on Plant Health performed a pest categorisation of Xylotrechus chinensis (Coleoptera: Cerambycidae) for the EU territory. This species is not included in the EU Commission Implementing Regulation 2019/2072. X. chinensis is native to China, Japan, the Korean peninsula and Taiwan. It has recently been reported from Spain (Cata...
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Plant pest invasions cost billions of Euros each year in Europe. Prediction of likely places of pest introduction could greatly help focus efforts on prevention and control and thus reduce societal costs of pest invasions. Here, we test whether generic data-driven risk maps of pest introduction, valid for multiple species and produced by machine le...
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Abstract The EFSA Panel on Plant Health performed a pest categorisation of the black vine thrips, Retithrips syriacus (Thysanoptera: Thripidae), for the EU territory. This species is not included in EU Commission Implementing Regulation 2019/2072. This polyphagous species feeds, among others, on apple, avocado, banana, cotton, grapevine, persimmon,...
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Abstract The EFSA Panel on Plant Health performed a pest categorisation of the snout moth Leucinodes pseudorbonalis Mally, Korycinska, Agassiz, Hall, Hodgetts & Nuss (Lepidoptera: Crambidae), for the territory of the EU. This species is not included in the EU Commission Implementing Regulation 2019/2072. This oligophagous species, which feeds on fr...