U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Forage Seed and Cereal Research Unit: Corvallis, OR
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Corvallis, Oregon Forage Seed and Cereal Research Unit People





- Find a person
- Find a location
- ARS Organizational Chart
- People

David  Gent

(Dave)    Research Plant Pathologist 3450 SW Campus WayCorvallis, OR 97331(541) 738-4167
 My research project is focused on developing effective, economical, and sustainable pest management strategies for priority diseases of hops that will reduce purchased inputs, increase crop productivity, and enhance economic development of rural communities. Current efforts are focused on the two primary diseases of this crop, powdery mildew (caused by Podosphaera macularis) and downy mildew (caused by Pseudoperonospora humuli), and integration of disease and arthropod pest management tactics within a systems context. Outbreaks of these diseases occur annually in hop production regions in the western U.S., and are conservatively estimated to cost the U.S.hop industry greater than $10 million annually in additional production expenses and crop loss. Research in my lab seeks to understand aspects of the epidemiology, ecology, and population biology of these pathogens and their diseases that will lead to new disease management approaches that can be implemented at the farm level. These objectives are achieved through integration of fundamental and applied research, collaborations with other researchers in the U.S.and abroad, and hands-on technology transfer with stakeholders. David Gent *CV* Field Guide for Integrated Pest Management in Hops - 2nd Ed., 2010 Field Guide for Integrated Pest Management in Hops - Pocket Version, English and Spanish
 ProjectsDevelopment of Superior Hops and Resilient Hop Production SystemsIn-House Appropriated (D)Accession Number:445259Enhancing Supply Chain Sustainability and Global Competitiveness for Pacific Northwest HopsReimbursable Cooperative Agreement (R)Accession Number:441418Integrated Management Strategies for Emerging and Re-emerging Cone Diseases Threatening the US Hop IndustryReimbursable Cooperative Agreement (R)Accession Number:442543  Publications(Clicking on the reprint iconReprint Icon  will take you to the publication reprint.)Characterization of powdery mildew fungi affecting hemp in the Pacific Northwest-(Peer Reviewed Journal)Plant disease warning systems-(Book / Chapter)Identification of quantitative trait loci involved in R1-mediated resistance to powdery mildew and sex determination in hop (Humulus lupulus L.)-(Peer Reviewed Journal) Havill, J.S., Richardson, B.J., Rohwer, C.L., Gent, D.H., Henning, J.A., Muehlbauer, G.J. 2023. Identification of quantitative trait loci involved in R1-mediated resistance to powdery mildew and sex determination in hop (Humulus lupulus L.). Journal of Theoretical and Applied Genetics. 136. Article 154. https://doi.org/10.1007/s00122-023-04399-7.Evolution of the genetic structure of the Didymella tanaceti population during development of succinate dehydrogenase
inhibitor resistance-(Peer Reviewed Journal) Pearce, T., Scott, J., Wilson, C., Gent, D.H. 2023. Evolution of the genetic structure of the Didymella tanaceti population during development of succinate dehydrogenase inhibitor resistance. Phytopathology. 113:1946-1958. https://doi.org/10.1094/PHYTO-10-22-0385-R.Nitrogen and sulfur fertility practices: Influences on hop chemistry, aroma, and nitrate accumulation-(Peer Reviewed Journal) Gent, D.H., Block, M., Massie, S.T., Phillips, C.L., Richardson, B.J., Shellhammer, T.H., Trippe, K.M., Wiseman, M.S. 2023. Nitrogen and sulfur fertility practices: Influences on hop chemistry, aroma, and nitrate accumulation. Journal of the American Society of Brewing Chemists. https://doi.org/10.1080/03610470.2023.2204412.Impact of infection timing and autumnal fungicide applications on perennation of pseudoperonospora humuli and severity of hop downy mildew-(Peer Reviewed Journal) Richardson, B.J., Gent, D.H. 2023. Impact of infection timing and autumnal fungicide applications on perennation of pseudoperonospora humuli and severity of hop downy mildew. Plant Disease. https://doi.org/10.1094/PDIS-02-23-0268-RE.Characterization of podosphaera macularis on the most prevalent hop genotype in the pacific northwest-(Peer Reviewed Journal) Gent, D.H., Block, M., Cooperider, C., Wiseman, M. 2023. Characterization of podosphaera macularis on the most prevalent hop genotype in the pacific northwest. PhytoFrontiers. https://doi.org/10.1094/PHYTOFR-02-23-0020-R.Yard age, cultivar susceptibility, and spring pruning practices as risk factors for overwintering of Podosphaera macularis on hop-(Peer Reviewed Journal) Laurie, R.W., Richardson, B.J., Ross, C.J., Gent, D.H. 2022. Yard age, cultivar susceptibility, and spring pruning practices as risk factors for overwintering of Podosphaera macularis on hop. PhytoFrontiers. https://doi.org/10.1094/PHYTOFR-10-22-0112-R.Genetic characterization of downy mildew resistance from the hop (Humulus lupulus L.) line USDA 64035M-(Peer Reviewed Journal) Olatoye, O.M., Wiseman, M., Gent, D.H., Henning, J.A., Altendorf, K.R. 2022. Genetic characterization of downy mildew resistance from the hop (Humulus lupulus L.) line USDA 64035M. Crop Science. 63(3):1082-1091. https://doi.org/10.1002/csc2.20880.Registration of seven powdery mildew-resistant wild hop germplasm lines-(Peer Reviewed Journal) Havill, J.S., Wiseman, M.S., Henning, J.A., Gent, D.H., Muehlbauer, G.J. 2022. Registration of seven powdery mildew-resistant wild hop germplasm lines. Journal of Plant Registrations. 17(1):171-179. https://doi.org/10.1002/plr2.20255.A quantitative PCR assay for detection and quantification of Fusarium sambucinum-(Peer Reviewed Journal) Thomas, W.J., Borland, T.G., Bergl, D.D., Claassen, B.J., Flodquist, T.A., Montgomery, A.S., Rivedal, H.M., Woodhall, J., Ocamb, C.M., Gent, D.H. 2022. A quantitative PCR assay for detection and quantification of Fusarium sambucinum. Plant Disease. 106:2601-2606. https://doi.org/10.1094/PDIS-02-22-0269-RE.Temperature influences on powdery mildew susceptibility and development in the hop cultivar Cascade-(Peer Reviewed Journal) Gent, D.H., Claassen, B.J., Wiseman, M.S., Wolfenbarger, S.N. 2022. Temperature influences on powdery mildew susceptibility and development in the hop cultivar Cascade. Plant Disease. 106(6):1681-1689. https://doi.org/10.1094/PDIS-10-21-2133-RE.Hop quality factors and grower fertility practices-(Abstract Only) Gent, D.H. 2021. Hop quality factors and grower fertility practices. Meeting Abstract. In: American Hop Convention and Winter Meeting of the Hop Research Council; 1/18/21-1/22/21; Virtual.Fungicide physical mode of action: Impacts on suppression of hop powdery mildew-(Peer Reviewed Journal) Claassen, B.J., Wolfenbarger, S.N., Gent, D.H. 2022. Fungicide physical mode of action: Impacts on suppression of hop powdery mildew. Plant Disease. 106(6):1244-1252. https://doi.org/10.1094/pdis-10-21-2131-re.A general framework for spatio-temporal modeling of epidemics with multiple epicenters: Application to an aerially dispersed plant pathogen-(Peer Reviewed Journal) Ojwang, A.M., Ruiz, T., Bhattacharyya, S., Chatterjee, S., Ojiambo, P.S., Gent, D.H. 2021. A general framework for spatio-temporal modeling of epidemics with multiple epicenters: Application to an aerially dispersed plant pathogen. Frontiers in Applied Mathematics and Statistics. 7. Article 721352. https://doi.org/10.3389/fams.2021.721352.Nitrogen fertility practices in the field influence the accumulation of nitrate during the production of hop-forward beer-(Peer Reviewed Journal) Shellhammer, T.H., Lafontaine, S.R., Iskra, A.E., Clawson, J., Trippe, K.M., Phillips, C.L., Gent, D.H. 2021. Nitrogen fertility practices in the field influence the accumulation of nitrate during the production of hop-forward beer. BrewingScience. 74:88-91. https://doi.org/10.23763/BrSc21-08shellhammer.Management of hop powdery mildew in the context of recent advances in pathogen ecology and population genetics-(Peer Reviewed Journal) Weldon, W.A., Gent, D.H., Gadoury, D.M. 2021. Management of hop powdery mildew in the context of recent advances in pathogen ecology and population genetics. Plant Health Progress. 22(4):450-458. https://doi.org/10.1094/PHP-03-21-0065-SYN.First report of powdery mildew caused by Podosphaera macularis on hemp in Oregon-(Peer Reviewed Journal) Bates, T.A., Block, M.H., Wiseman, M.S., Garfinkel, A.R., Gent, D.H., Ocamb, C.M. 2021. First report of powdery mildew caused by Podosphaera macularis on hemp in Oregon. Plant Health Progress. 22(4):567-569. https://doi.org/10.1094/PHP-04-21-0071-BR.A comprehensive characterization of ecological and epidemiological factors driving perennation of Podosphaera macularis chasmothecia-(Peer Reviewed Journal) Weldon, W.A., Marks, M.E., Gevens, A.J., D'Arcangelo, K., Quesada-Ocampo, L.M., Parry, S., Gent, D.H., Cadle Davidson, L.E., Gadoury, D.M. 2021. A comprehensive characterization of ecological and epidemiological factors driving perennation of Podosphaera macularis chasmothecia. American Phytopathological Society. https://doi.org/10.1094/PHYTO-11-20-0492-R.Registration of high-yielding aroma hop (Humulus lupulus L.) cultivar, ‘USDA Triumph'-(Peer Reviewed Journal) Henning, J.A., Townsend, M., Gent, D.H., Wiseman, M., Walsh, D., Groenendale, D., Randazzo, A. 2021. Registration of high-yielding aroma hop (Humulus lupulus L.) cultivar, ‘USDA Triumph'. Journal of Plant Registrations. 15(2):244-252. https://doi.org/10.1002/plr2.20138.The hop downy mildew pathogen Pseudoperonospora humuli-(Review Article) Purayannur, S., Gent, D.H., Miles, T.D., Radisek, S., Quesada-Ocampo, L. 2021. The hop downy mildew pathogen Pseudoperonospora humuli. Molecular Plant Pathology. 22(7):755-768. https://doi.org/10.1111/mpp.13063.Characterization of Podosphaera macularis derived from the hop cultivar ‘Strata’ and resistance to powdery mildew-(Peer Reviewed Journal) Block, M., Wiseman, M.S., Gent, D.H. 2021. Characterization of Podosphaera macularis derived from the hop cultivar ‘Strata’ and resistance to powdery mildew. Plant Health Progress. 22(2):154-156. https://doi.org/10.1094/PHP-11-20-0095-BR.A multiplex TaqMan qPCR assay for detection and quantification of clade 1 and clade 2 isolates of Pseudoperonospora cubensis and Pseudoperonospora humuli-(Peer Reviewed Journal) Crandall, S.G., Ramon, M.L., Burkhardt, A.K., Bello, J.C., Adair, N., Gent, D.H., Hausbeck, M.K., Quesada-Ocampo, L.M., Martin, F.N. 2021. A multiplex TaqMan qPCR assay for detection and quantification of clade 1 and clade 2 isolates of Pseudoperonospora cubensis and Pseudoperonospora humuli. Plant Disease. https://doi.org/10.1094/PDIS-11-20-2339-RE.Delayed early season irrigation: impacts on hop yield and quality-(Peer Reviewed Journal) Gent, D.H., Claassen, B.J., Massie, S.T., Phillips, C.L., Shellhammer, T.H., Trippe, K.M., Twomey, M.C. 2021. Delayed early season irrigation: impacts on hop yield and quality. Journal of the American Society of Brewing Chemists. 80:62-65. https://doi.org/10.1080/03610470.2021.1915053.Registration of high-yielding aroma hop (Humulus lupulus L.) cultivar ‘USDA Triumph’-(Germplasm Registration) Henning, J.A., Townsend, M.S., Gent, D.H., Wiseman, M.S., Walsh, D.B., Groenendale, D.P. 2021. Registration of high-yielding aroma hop (Humulus lupulus L.) cultivar ‘USDA Triumph’. Journal of Plant Registrations. 15(2):244-252. https://doi.org/10.1002/plr2.20138.Evaluation of fungicides for hop powdery mildew, study 1, Granger, Washington, 2020-(Abstract Only) Massie, S.T., Classen, B.J., Gent, D.H. 2021. Evaluation of fungicides for hop powdery mildew, study 1, Granger, Washington, 2020. Plant Disease Management Reports. 15:V030. https://doi.org/10.1094/PDMR15.Evaluation of fungicides for hop downy mildew, Hubbard, Oregon, 2020-(Other) Classen, B.J., Adair, N.L., Gent, D.H. 2021. Evaluation of fungicides for hop downy mildew, Hubbard, Oregon, 2020. Plant Disease Management Reports. 15:V031. https://doi.org/10.1094/PDMR15.First report of powdery mildew caused by Golovinomyces ambrosiae on Cannabis sativa in Oregon-(Peer Reviewed Journal) Wiseman, M., Ocamb, C., Bates, T., Garfinkle, A., Gent, D.H. 2021. First report of powdery mildew caused by Golovinomyces ambrosiae on Cannabis sativa in Oregon. Plant Disease. https://doi.org/10.1094/PDIS-11-20-2455-PDN.Evaluation of fungicides for hop powdery mildew, study 2, Granger, Washington, 2020-(Other) Massie, S.T., Claassen, B.J., Gent, D.H. 2021. Evaluation of fungicides for hop powdery mildew, study 2, Granger, Washington, 2020. Plant Disease Management Reports. 15:V074. https://doi.org/10.1094/PDMR15.Predicting damage to hop cones by Tetranychus urticae (Acari: Tetranychidae)-(Peer Reviewed Journal) Woods, J.L., Iskra, A.E., Gent, D.H. 2021. Predicting damage to hop cones by Tetranychus urticae (Acari: Tetranychidae). Environmental Entomology. 50(3):673-684. https://doi.org/10.1093/ee/nvab008.Transcriptome-derived amplicon sequencing (AmpSeq) markers elucidate the U.S. podosphaera macularis population structure across feral and commercial plantings of Humulus lupulus-(Peer Reviewed Journal) Weldon, W.A., Knaus, B.J., Grunwald, N.J., Havill, J.M., Block, M.H., Gent, D.H., Cadle Davidson, L.E., Gadoury, D.M. 2020. Transcriptome-derived amplicon sequencing (AmpSeq) markers elucidate the U.S. podosphaera macularis population structure across feral and commercial plantings of Humulus lupulus. Phytopathology. 111:194-203. https://doi.org/10.1094/PHYTO-07-20-0299-FI.Development of a diagnostic assays for race differentiation of Podophaera macularis-(Peer Reviewed Journal) Block, M., Knaus, B.J., Wiseman, M., Grunwald, N.J., Gent, D.H. 2021. Development of a diagnostic assays for race differentiation of Podophaera macularis. Plant Disease. 105(4):965–971. https://doi.org/10.1094/PDIS-06-20-1289-RE.The effector repertoire of the hop downy mildew pathogen, Pseudoperonospora humuli-(Peer Reviewed Journal) Purauannur, S., Cano, L.M., Bowman, M.J., Childs, K.L., Gent, D.H., Quesada-Ocampo, L.M. 2020. The effector repertoire of the hop downy mildew pathogen, Pseudoperonospora humuli. Frontiers in Genetics. 11. https://doi.org/10.3389/fgene.2020.00910.Hop downy mildew caused by Pseudoperonospora humuli: A diagnostic guide-(Peer Reviewed Journal) Purayannur, S., Miles, T.D., Gent, D.H., Pigg, S., Quesada-Ocampo, L.M. 2020. Hop downy mildew caused by Pseudoperonospora humuli: A diagnostic guide. Plant Health Progress. 21(3):173-179. https://doi.org/10.1094/PHP-10-19-0072-DG.Population diversity and structure of Podosphaera macularis in the Pacific Northwestern U.S. and other populations-(Peer Reviewed Journal) Gent, D.H., Claassen, B.J., Gadoury, D.M., Grunwald, N.J., Knaus, B.J., Radisek, S., Weldon, W., Wiseman, M.S., Wolfenbarger, S.N. 2020. Population diversity and structure of Podosphaera macularis in the Pacific Northwestern U.S. and other populations. Phytopathology. 110(5):1106-1116. https://doi.org/10.1094/PHYTO-12-19-0448-R.Evaluation of fungicides for hop powdery mildew, study 1, Granger, Washington, 2019-(Other) Massie, S.T., Claassen, B.J., Gent, D.H. 2020. Evaluation of fungicides for hop powdery mildew, study 1, Granger, Washington, 2019. Plant Disease Management Reports. 14:V051. https://doi.org/10.1094/PDMR14.Evaluation of fungicides for hop powdery mildew, study 2, Granger, Washington, 2019-(Other) Massie, S.T., Claassen, B.J., Gent, D.H. 2020. Evaluation of fungicides for hop powdery mildew, study 2, Granger, Washington, 2019. Plant Disease Management Reports. 14:V051. https://doi.org/10.1094/PDMR14.High levels of insensitivity to phosphonate fungicides in Pseudoperonospora humuli-(Peer Reviewed Journal) Gent, D.H., Block, M., Claassen, B. 2020. High levels of insensitivity to phosphonate fungicides in Pseudoperonospora humuli. Plant Disease. 104(5):1400-1406. https://doi.org/10.1094/PDIS-10-19-2067-RE.Genotyping-by-sequencing reveals fine-scale population differentiation in populations of Pseudoperonospora humuli-(Peer Reviewed Journal) Gent, D.H., Adair, N.L., Knaus, B.J., Grunwald, N.J. 2019. Genotyping-by-sequencing reveals fine-scale population differentiation in populations of Pseudoperonospora humuli. Phytopathology. https://doi.org/10.1094/PHYTO-12-18-0485-R.Multiple mutations across the succinate dehydrogenase gene complex are associated with boscalid resistance in Didymella tanaceti in pyrethrum-(Peer Reviewed Journal) Pearce, T.L., Scott, J.B., Wilson, C.R., Gent, D.H., Pethybridge, S.J., Hay, F.S. 2019. Multiple mutations across the succinate dehydrogenase gene complex are associated with boscalid resistance in Didymella tanaceti in pyrethrum. PLoS One. 14(6):e0218569. https://doi.org/10.1371/journal.pone.0218569.Cooperation and coordination in plant disease management-(Peer Reviewed Journal) Sherman, J., Burke, J., Gent, D.H. 2019. Cooperation, and coordination in plant disease management. Phytopathology. https://doi.org/10.1094/PHYTO-01-19-0010-R.Stability and resiliency of biological control of the twospotted spider mite (Acari: Tetranychidae) in hop-(Peer Reviewed Journal) Iskra, A.E., Woods, J.L., Gent, D.H. 2019. Stability and resiliency of biological control of the twospotted spider mite (Acari: Tetranychidae) in hop. Environmental Entomology. 48(4):894-902. https://doi.org/10.1093/ee/nvz071.Influence of nitrogen fertility practices on hop cone quality-(Peer Reviewed Journal) Iskra, A., Lafontaine, S., Trippe, K.M., Massie, S., Phillips, C.L., Towney, M., Shellhammer, T., Gent, D.H. 2019. Influence of nitrogen fertility practices on hop cone quality. Journal of American Society of Brewing Chemists. 73(3):199-209. https://doi.org/10.1080/03610470.2019.1616276.Genome sequencing and transcriptome analysis of the hop downy mildew pathogen Pseudoperonospora humuli reveal species-specific genes for  molecular detection-(Peer Reviewed Journal) Rahman, A., Gongora-Castillo, E., Bowman, M., Childs, K., Gent, D.H., Martin, F.N., Quesada-Ocampo, L.M. 2019. Genome sequencing and transcriptome analysis of the hop downy mildew pathogen Pseudoperonospora humuli reveal species-specific genes for molecular detection. Phytopathology. 109(8):1354-1366. https://doi.org/10.1094/PHYTO-11-18-0431-R.Prediction of spread and regional development of hop powdery mildew: A network analysis-(Peer Reviewed Journal) Gent, D.H., Bhattacharyya, S., Ruiz, T. 2019. Prediction of spread and regional development of hop powdery mildew: A network analysis. Phytopathology. 109(8):1392-1403. https://doi.org/10.1094/PHYTO-12-18-0483-R.Evaluation of fungicides for hop powdery mildew, study 1, Toppenish, Washington, 2018-(Other) Massie, S.T., Claassen, B.J., Gent, D.H. 2019. Evaluation of fungicides for hop powdery mildew, study 1, Toppenish, Washington, 2018. Plant Disease Management Reports. 13:V025.Evaluation of fungicides for hop downy mildew and powdery mildew, Prosser, Washington, 2018-(Other) Massie, S.T., Claassen, B.J., Gent, D.H. 2019. Evaluation of fungicides for hop downy mildew and powdery mildew, Prosser, Washington, 2018. Plant Disease Management Reports. 13:V026.Evaluation of fungicides for hop powdery mildew, study 2, Toppenish, Washington, 2018-(Other) Massie, S.T., Claassen, B.J., Gent, D.H. 2019. Evaluation of fungicides for hop powdery mildew, study 2, Toppenish, Washington, 2018. Plant Disease Management Reports. 13:V027.Identification of resistance to powdery mildew in publically-available male hop germplasm-(Peer Reviewed Journal) Gent, D.H., Claassen, B.J., Twomey, M.C., Wolfenbarger, S.N. 2018. Identification of resistance to powdery mildew in publically-available male hop germplasm. Plant Health Progress. 19(3):258-264. https://doi.org/10.1094/PHP-05-18-0027-RS.Risk factors for bud perennation of Podosphaera macularis on hop-(Peer Reviewed Journal) Gent, D.H., Mahaffee, W.F., Turechek, W., Ocamb, C.M., Twomey, M.C., Woods, J.L., Probst, C. 2018. Risk factors for bud perennation of Podosphaera macularis on hop. Phytopathology. https://doi.org/10.1094/PHYTO-04-18-0127-R.Influence of nitrogen fertilizer rate on hop looper-(Peer Reviewed Journal) Iskra, A.E., Woods, J.L., Gent, D.H. 2018. Influence of nitrogen fertilizer rate on hop looper. Journal of Economic Entomology. 111(5):2499-2502. https://doi.org/10.1093/jee/toy229.Registration of high alpha-acid male hop germplasm 'USDA 21267M'-(Peer Reviewed Journal) Henning, J.A., Gent, D.H., Townsend, M.S., Haunold, A. 2018. Registration of high alpha-acid male hop germplasm 'USDA 21267M'. Journal of Plant Registrations. 12:382-385. https://doi.org/10.3198/jpr2017.09.0068crg.Registration of downy mildew resistant male hop germplasm 'USDA 21087M'-(Peer Reviewed Journal) Henning, J.A., Gent, D.H., Townsend, M.S., Haunold, A. 2018. Registration of downy mildew resistant male hop germplasm 'USDA 21087M'. Journal of Plant Registrations. 12:379-381. https://doi.org/10.3198/jpr2017.09.0067crg.Susceptibility of Hop crown buds to powdery mildew and its relation to perennation of Podosphaera macularis-(Peer Reviewed Journal) Gent, D.H., Claassen, B.J., Twomey, M.C., Wolfenbarger, S.N., Woods, J.L. 2018. Susceptibility of Hop crown buds to powdery mildew and its relation to perennation of Podosphaera macularis. Plant Disease. 102(7):1316-1325.Statistical power in plant pathology research-(Peer Reviewed Journal) Gent, D.H., Esker, P.D., Kriss, A.B. 2018. Statistical power in plant pathology research. Phytopathology. 108(1):15-22.Mycoflora associated with pyrethrum seed and the integration of seed steam treatment into foliar disease management strategies-(Peer Reviewed Journal) Scott, J.B., Gent, D.H., Pearce, T.L., Pethybridge, S.J., Pilkington, S.J., Hay, F.S. 2017. Mycoflora associated with pyrethrum seed and the integration of seed steam treatment into foliar disease management strategies. Plant Disease. 101(11):1874-1884.Focus expansion and stability of the spread parameter estimate of the power law model for dispersal gradients-(Peer Reviewed Journal) Ojiambo, P.S., Gent, D.H., Mehra, L.K., Christie, D., Magarey, R. 2017. Focus expansion and stability of the spread parameter estimate of the power law model for dispersal gradients. PeerJ. doi: 10.7717/peerj.3465.Infestation of hop seed (Humulus lupulus) by chasmothecia of the powdery mildew fungus, Podosphaera macularis-(Peer Reviewed Journal) Claassen, B.J., Wolfenbarger, S.N., Havill, J.S., Orshinsky, A.M., Gent, D.H. 2017. Infestation of hop seed (Humulus lupulus) by chasmothecia of the powdery mildew fungus, Podosphaera macularis. Plant Disease. 101(7):1323.Homothallism in Pseudoperonospora humuli-(Peer Reviewed Journal) Gent, D.H., Cohen, Y., Runge, F. 2017. Homothallism in Pseudoperonospora humuli. Plant Pathology. doi: 10.1111/ppa.12689.Adaptation to partial resistance to powdery mildew in the hop cultivar Cascade by Podosphaera macularis-(Peer Reviewed Journal) Gent, D.H., Massie, S.T., Twomey, M.C., Wolfenbarger, S.N. 2017. Adaptation to partial resistance to powdery mildew in the hop cultivar Cascade by Podosphaera macularis. Plant Disease. 101(6):874-881.Evaluation of fungicides for hop downy mildew, Hubbard, Oregon, 2016-(Other) Gent, D.H. 2017. Evaluation of fungicides for hop downy mildew, Hubbard, Oregon, 2016. Plant Disease Management Reports. 11:V048.Evaluation of fungicides for hop downy mildew, Woodburn, Oregon, 2016-(Other) Gent, D.H. 2017. Evaluation of fungicides for hop downy mildew, Woodburn, Oregon, 2016. Plant Disease Management Reports. 11:V047.Powdery mildew reaction of hop cultivars and USDA germplasm, 2015-(Other) Wolfenbarger, S.N., Twomey, M.C., Gent, D.H. 2017. Powdery mildew reaction of hop cultivars and USDA germplasm, 2015. Plant Disease Management Reports. 11:V049.Climate, weather, and hops-(Other) Morton, L.W., Gent, D.H., Gleason, M. 2017. Climate, weather, and hops. Sociology Technical Report 1045, Department of Sociology, Iowa State University. 24pp.QTL analysis of resistance to powdery mildew in Hop (Humulus lupulus L.)-(Peer Reviewed Journal) Henning, J.A., Gent, D.H., Townsend, M.S., Twomey, M., Hill, S.T., Hendrix, D. 2017. QTL analysis of resistance to powdery mildew in Hop (Humulus lupulus L.). Euphytica. 213:98. doi: 10.1007/s10681-017-1849-9.Using next-generation sequencing to develop molecular diagnostics for Pseudoperonospora cubensis, the cucurbit downy mildew pathogen-(Peer Reviewed Journal) Withers, S., Gongora-Castillo, E., Gent, D.H., Thomas, A., Ojiambo, P., Quesada-Ocampo, L. 2016. Using next-generation sequencing to develop molecular diagnostics for Pseudoperonospora cubensis, the cucurbit downy mildew pathogen. Phytopathology. doi: 10.1094/PHYTO-10-15-0260-FI.Susceptibility of hop cultivars to downy mildew: associations with chemical characteristics and region of origin-(Peer Reviewed Journal) Woods, J., Gent, D.H. 2016. Susceptibility of hop cultivars to downy mildew: associations with chemical characteristics and region of origin. Plant Health Progress. 17:42-48.Identification of extrachromosomal circular DNA in hop via rolling circle amplification-(Peer Reviewed Journal) Diaz-Lara, A., Gent, D.H., Martin, R.R. 2016. Identification of extrachromosomal circular DNA in hop via rolling circle amplification. Cytogenetics and Genome Research. 148(2-3):237-240. doi: 10.1159/000445849.Powdery mildew caused by Podosphaera macularis on hop (Humulus lupulus) in North Carolina-(Peer Reviewed Journal) Wolfenbarger, S.N., Quesada-Ocampo, L.M., Gent, D.H. 2016. Powdery mildew caused by Podosphaera macularis on hop (Humulus lupulus) in North Carolina. Plant Disease. 100(6):1245. doi: 10.1094/PDIS-12-15-1525-PDN.Hop powdery mildew control through alteration of spring pruning practices-(Peer Reviewed Journal) Probst, C., Nelson, M.E., Grove, G.G., Twomey, M.C., Gent, D.H. 2016. Hop powdery mildew control through alteration of spring pruning practices. Plant Disease. 100(8):1599-1605. doi: 10.1094/PDIS-10-15-1127-RE.Distribution and characterization of Podosphaera macularis virulent on hop cultivars possessing R6-based resistance to powdery mildew-(Peer Reviewed Journal) Wolfenbarger, S.N., Massie, S.T., Ocamb, C., Eck, E.B., Grove, G.G., Nelson, M.E., Probst, C., Twomey, M.C., Gent, D.H. 2016. Distribution and characterization of Podosphaera macularis virulent on hop cultivars possessing R6-based resistance to powdery mildew. Plant Disease. 100(6):1212-1221. doi: 10.1094/PDIS-12-15-1449-RE.Interaction of basal foliage removal and late season fungicide applications in management of Hop powdery mildew-(Peer Reviewed Journal) Gent, D.H., Probst, C., Nelson, M.E., Grove, G.G., Massie, S.T., Twomey, M.C. 2016. Interaction of basal foliage removal and late season fungicide applications in management of Hop powdery mildew. Plant Disease. 100:1153-1160.Black wilt of hop (Humulus lupulus) caused by Diplodia seriata in New York State-(Peer Reviewed Journal) Twomey, M.C., Stone, J.K., Gent, D.H. 2016. Black wilt of hop (Humulus lupulus) caused by Diplodia seriata in New York State. Plant Disease. 100(4):861. doi: 10.1094/PDIS-10-15-1140-PDN.Genotyping-by-sequencing of a bi-parental mapping population segregating for downy mildew resistance in hop (Humulus lupulus L.)-(Peer Reviewed Journal) Henning, J.A., Gent, D.H., Twomey, M.C., Townsend, M.S., Pitra, N.J., Matthews, P.D. 2015. Genotyping-by-sequencing of a bi-parental mapping population segregating for downy mildew resistance in hop (Humulus lupulus L.). Euphytica. 208(3):545-559. doi: 10.1007/s10681-015-1600-3.Identification of genetic variation between obligate plant pathogens Psuedoperonospora cubensis and P. humuli using RNA sequencing and genotyping-by-sequencing-(Peer Reviewed Journal) Summers, C., Gulliford, C., Lillis, J.A., Carlson, M., Cadle Davidson, L.E., Gent, D.H., Smart, C. 2015. Identification of genetic variation between obligate plant pathogens Psuedoperonospora cubensis and P. humuli using RNA sequencing and genotyping-by-sequencing. PLoS One. doi: 10.1371/journal.pone.0143665.Estimation of pyrethrum flower number using digital imagery-(Peer Reviewed Journal) Scott, J.B., Gent, D.H., Hay, F.S., Pethybridge, S.J. 2015. Estimation of pyrethrum flower number using digital imagery. HortTechnology. 25(5):617-624.Pseudoperonospora cubensis and P. humuli detection using species-specific probes and high definition melt curve analysis-(Peer Reviewed Journal) Summers, C.F., Adair, N.L., Gent, D.H., Mcgrath, M.T., Smart, C.D. 2015. Pseudoperonospora cubensis and P. humuli detection using species-specific probes and high definition melt curve analysis. Canadian Journal of Plant Pathology. 37(3):315-330.Epidemiology and population biology of pseudoperonospora cubensis: a model system for management of downy mildews-(Peer Reviewed Journal) Ojiambo, P.S., Gent, D.H., Quesada-Ocampo, L.M., Hausbeck, M.K., Holmes, G.J. 2015. Epidemiology and population biology of pseudoperonospora cubensis: a model system for management of downy mildews. Annual Review of Phytopathology. 53:223-246.Carpogenic germination of sclerotia of Sclerotinia minor and ascosporic infection of pyrethrum flowers-(Peer Reviewed Journal) O'Malley, T.B., Hay, F.S., Scott, J.B., Gent, D.H., Shivas, R.G., Pethybridge, S.J. 2015. Carpogenic germination of sclerotia of Sclerotinia minor and ascosporic infection of pyrethrum flowers. Canadian Journal of Plant Pathology. 37:179-187.Risk and maximum residue limits: a study of hops production-(Peer Reviewed Journal) Zhang, R., Marsh, T., Gent, D.H. 2015. Risk and maximum residue limits: a study of hops production. Journal of Agricultural Science. 7(5):85-93.A polymerase chain reaction assay for ascosporic inoculum of Sclerotinia species-(Peer Reviewed Journal) Jones, S.J., Pilkington, S., Gent, D.H., Hay, F.S., Pethybridge, S.J. 2015. A polymerase chain reaction assay for ascosporic inoculum of Sclerotinia species. New Zealand Journal of Crop and Horticultural Science. 43(3):233-240.Development of partial ontogenic resistance to powdery mildew in Hop cones and its management implications-(Peer Reviewed Journal) Twomey, M.C., Wolfenbarger, S.N., Woods, J.L., Gent, D.H. 2015. Development of partial ontogenic resistance to powdery mildew in Hop cones and its management implications. PLoS One. 10(3):e0120987.Changes in distribution and frequency of fungi associated with a foliar disease complex of pyrethrum in Australia-(Peer Reviewed Journal) Hay, F., Gent, D.H., Pilkington, S., Pearce, T., Scott, J.B., Pethybridge, S.J. 2015. Changes in distribution and frequency of fungi associated with a foliar disease complex of pyrethrum in Australia. Plant Disease. 99:1227-1235.Precision QTL mapping of downy mildew resistance in Hop (Humulus lupulus L.)-(Peer Reviewed Journal) Henning, J.A., Gent, D.H., Twomey, M., Townsend, M.S., Pitra, N., Matthews, P. 2015. Precision QTL mapping of downy mildew resistance in Hop (Humulus lupulus L.). Euphytica. 202(3):487-498.Pre- and post-infection activity of fungicides in control of hop downy mildew-(Peer Reviewed Journal) Gent, D.H., Twomey, M.C., Wolfenbarger, S.N., Woods, J.L. 2015. Pre- and post-infection activity of fungicides in control of hop downy mildew. Plant Disease. 99:858-865.Identification and distribution of the mating-type idiomorphs in populations of Podosphaera macularis and development of chasmothecia of the fungus-(Peer Reviewed Journal) Wolfenbarger, S.N., Twomey, M.C., Gadoury, D., Knaus, B.J., Grunwald, N.J., Gent, D.H. 2015. Identification and distribution of the mating-type idiomorphs in populations of Podosphaera macularis and development of chasmothecia of the fungus. Plant Pathology. 64:1094-1102.Thrips tabaci (Thysanoptera: Thripidae) and Iris yellow spot virus associated with onion transplants, onion volunteers, and weeds in Colorado-(Peer Reviewed Journal) Schwartz, H.F., Gent, D.H., Fichtner, S.M., Otto, K., Boateng, C., Szostek, S., Cranshaw, W., Mahaffey, L. 2014. Thrips tabaci (Thysanoptera: Thripidae) and Iris yellow spot virus associated with onion transplants, onion volunteers, and weeds in Colorado. Southwestern Entomologist. 39(4):691-704.Meta-analysis reveals a critical period for management of powdery mildew on Hop cones-(Peer Reviewed Journal) Nelson, M.E., Gent, D.H., Grove, G.G. 2015. Meta-analysis reveals a critical period for management of powdery mildew on Hop cones. Plant Disease. 99:632-640.Concepts of sustainability, motivations for pest management approaches, and implications for communicating change-(Peer Reviewed Journal) Sherman, J., Gent, D.H. 2014. Concepts of sustainability, motivations for pest management approaches, and implications for communicating change. Plant Disease. 98(8):1024-1035.Red crown rot of Hop in Oregon caused by Phomopsis tuberivora-(Peer Reviewed Journal) Gent, D.H., Mueller Warrant, G.W., Woods, J.L., Putnam, M., Twomey, M. 2014. Red crown rot of Hop in Oregon caused by Phomopsis tuberivora. Plant Health Progress. doi: 10.1094/PHP-2014-0624-01-BR.Development of biological control of Tetranychus urticae (Acari:Tetranychidae) and Phorodon humuli (Hemiptera: Aphididae) in Oregon Hop yards-(Peer Reviewed Journal) Woods, J.L., Dreves, A.J., James, D.G., Lee, J.C., Walsh, D.B., Gent, D.H. 2014. Development of biological control of Tetranychus urticae (Acari:Tetranychidae) and Phorodon humuli (Hemiptera: Aphididae) in Oregon Hop yards. Journal of Economic Entomology. 107(2):570-581.Characterization of resistance to powdery mildew in the Hop cultivars Newport and Comet-(Peer Reviewed Journal) Wolfenbarger, S.N., Eck, E.B., Gent, D.H. 2014. Characterization of resistance to powdery mildew in the Hop cultivars Newport and Comet. Plant Health Progress. DOI:10.1094/PHP-BR-13-0129.Suppression of Hop Looper (Lepidoptera: Noctuidae) by the fungicide Pyraclostrobin-(Peer Reviewed Journal) Woods, J.L., Gent, D.H. 2014. Suppression of Hop Looper (Lepidoptera: Noctuidae) by the fungicide Pyraclostrobin. Journal of Economic Entomology. 107(2):875-879.Powdery mildew outbreaks caused by Podosphaera macularis on Hop cultivars possessing the resistance gene R6 in the Pacific Northwestern United States-(Peer Reviewed Journal) Wolfenbarger, S.N., Eck, E.B., Ocamb, C.M., Probst, C., Nelson, M.E., Grove, G.G., Gent, D.H. 2014. Powdery mildew outbreaks caused by Podosphaera macularis on Hop cultivars possessing the resistance gene R6 in the Pacific Northwestern United States. Plant Disease. 98(6):852-853.Crop damage caused by Powdery Mildew on Hop and its relationship to late season management-(Peer Reviewed Journal) Gent, D.H., Grove, G.G., Nelson, M.E., Wolfenbarger, S.N., Farnsworth, J.L. 2014. Crop damage caused by Powdery Mildew on Hop and its relationship to late season management. Plant Pathology. 63:625-639.Minimizing crop damage through understanding relationships between pyrethrum phenology and ray blight disease severity-(Peer Reviewed Journal) Pethybridge, S.J., Gent, D.H., Groom, T., Hay, F. 2013. Minimizing crop damage through understanding relationships between pyrethrum phenology and ray blight disease severity. Plant Disease. 97(11):1431-1437.Quantifying the effects of uniconazole on growth and yield of pyrethrum in Australia-(Peer Reviewed Journal) Pethybridge, S.J., Gent, D.H., Hingston, L., Frost, P. 2014. Quantifying the effects of uniconazole on growth and yield of pyrethrum in Australia. New Zealand Journal of Crop and Horticultural Science. 42(1):50-59.Spatiotemporal characterization of Sclerotinia crown rot epidemics in pyrethrum-(Peer Reviewed Journal) Scott, J.B., Gent, D.H., Pethybridge, S.J., Hay, F.S. 2014. Spatiotemporal characterization of Sclerotinia crown rot epidemics in pyrethrum. Plant Disease. (98):267-274.Crop damage from Sclerotinia crown rot and risk factors in pyrethrum-(Peer Reviewed Journal) Scott, J.B., Gent, D.H., Pethybridge, S.J., Groom, T., Hay, F. 2014. Crop damage from Sclerotinia crown rot and risk factors in pyrethrum. Plant Disease. 98:103-111.The use and role of predictive systems in disease management-(Peer Reviewed Journal) Gent, D.H., Mahaffee, W.F., Mcroberts, N., Pfender, W.F. 2013. The use and role of predictive systems in disease management. Annual Review of Phytopathology. 51:267-89.Association of spring pruning practices with severity of powdery mildew and downy mildew on hop-(Peer Reviewed Journal) Gent, D.H., Nelson, M., Grove, G., Mahaffee, W.F., Turechek, W., Woods, J. 2012. Association of spring pruning practices with severity of powdery mildew and downy mildew on hop. Plant Disease. 96:1343-1351.New outbreaks of verticillium wilt on Hop in Oregon caused by nonlethal verticillium albo-atrum-(Peer Reviewed Journal)Population density and phenology of Tetranychus urticae Koch (Acari: Tetranychidae) is linked to sulfur-induced outbreaks of this pest-(Peer Reviewed Journal) Woods, J.L., Dreves, A.M., Fisher, G.C., James, D.G., Wright, L.C., Gent, D.H. 2012. Population density and phenology of Tetranychus urticae Koch (Acari: Tetranychidae) is linked to sulfur-induced outbreaks of this pest. Environmental Entomology. 41:621-635.Sclerotinia wilt of Hop (Humulus lupulus) caused by Sclerotinia sclerotiorum in the Pacific Northwest U.S.-(Peer Reviewed Journal) Kropf, S.M., Twomey, M.C., Woods, J.L., Gent, D.H., Putnam, M.L., Serdani, M. 2012. Sclerotinia wilt of Hop (Humulus lupulus) caused by Sclerotinia sclerotiorum in the Pacific Northwest U.S. Plant Disease. 96: 583.Sensitivity of disease management decision aids to temperature input errors associated with out-of-canopy and reduced time-resolution measurements-(Peer Reviewed Journal) Pfender, W.F., Gent, D.H., Mahaffee, W.F. 2012. Sensitivity of disease management decision aids to temperature input errors associated with out-of-canopy and reduced time-resolution measurements. Plant Disease. 96:726-736.Evaluation of airborne methyl salicylate for improved conservation biological control of two-spotted spider mites and hop aphid in Oregon hop yards-(Peer Reviewed Journal) Woods, J., James, D., Lee, J.C., Gent, D.H. 2011. Evaluation of airborne methyl salicylate for improved conservation biological control of two-spotted spider mites and hop aphid in Oregon hop yards. Experimental and Applied Acarology. 55:401-416.Site-specific risk factors of white mould epidemics in bean (Phaseolus vulgaris) in Tasmania-(Peer Reviewed Journal)Evaluation of airborne methyl salicylate for improved conservation biological control of two-spotted spider mite and hop aphid in Oregon hop yards-(Peer Reviewed Journal) Woods, J.L., James, D.G., Lee, J.C., Gent, D.H. 2011. Evaluation of airborne methyl salicylate for improved conservation biological control of two-spotted spider mite and hop aphid in Oregon hop yards. Experimental and Applied Acarology. 55(4):401-416.Comments Regarding the Binary Power Law for Heterogeneity of Disease Incidence-(Peer Reviewed Journal) Turechek, W., Madden, L.V., Gent, D.H., Xu, X.M. 2011. Comments Regarding the Binary Power Law for Heterogeneity of Disease Incidence. Phytopathology. 101:1396-1407.Epidemics of ray blight on pyrethrum are linked to seed contamination and overwintering inoculum of Phoma ligulicola var. inoxydabilis-(Peer Reviewed Journal) Pethybridge, S.J., Gent, D.H., Hay, F.S. 2011. Epidemics of ray blight on pyrethrum are linked to seed contamination and overwintering inoculum of Phoma ligulicola var. inoxydabilis. Phytopathology. 101:1112-1121.Genetic and pathogenic relatedness of Pseudoperonospora cubensis and P. humuli-(Peer Reviewed Journal) Mitchell, M.N., Ocamb, C.M., Grunwald, N.J., Mancino, L.E., Gent, D.H. 2011. Genetic and pathogenic relatedness of Pseudoperonospora cubensis and P. humuli. Phytopathology. 101:805-818.Spatial characteristics of white mould epidemics and the development of sequential sampling plans in Australian bean fields-(Peer Reviewed Journal) Jones, S.J., Gent, D.H., Pethybridge, S.J., Hay, F.S. 2011. Spatial characteristics of white mould epidemics and the development of sequential sampling plans in Australian bean fields. Plant Pathology. DOI:10.1111/j.1365-3059.2011-02466.x.Sensitivity of Australian Sclerotinia sclerotiorum isolates from bean fields to boscalid-(Peer Reviewed Journal) Jones, S.J., Pethybridge, S.J., Gent, D.H., Hay, F.S. 2011. Sensitivity of Australian Sclerotinia sclerotiorum isolates from bean fields to boscalid. New Zealand Journal of Crop and Horticultural Science. 1:1-5.Spatial analysis and incidence-density relationships for downy mildew on hop-(Peer Reviewed Journal) Gent, D.H., Farnsworth, J.L., Johnson, D.A. 2011. Spatial analysis and incidence-density relationships for downy mildew on hop. Plant Pathology. DOI:10.1111/j.1365-3059.2011.02491.x.Decision Aids for Multiple-Decision Disease Management as Affected by Weather Input Errors-(Peer Reviewed Journal) Pfender, W.F., Gent, D.H., Mahaffee, W.F., Coop, L.B., Fox, A. 2011. Decision Aids for Multiple-Decision Disease Management as Affected by Weather Input Errors. Phytopathology. 101:644-653.Spatial and temporal distribution of iris yellow spot virus and thrips in Colorado onion fields-(Peer Reviewed Journal) Schwartz, H.F., Gent, D.H., Fichtner, S.M., Khosla, R., Mahaffey, L.A., Camper, M.A., Cranshaw, W.S. 2010. Spatial and temporal distribution of iris yellow spot virus and thrips in Colorado onion fields. Plant Health Progress. doi:10.1094/PHP-2010-0820-01-RS.Perceptions of risk, risk aversion, and barriers to adoption of decision support systems and integrated pest management: An introduction-(Peer Reviewed Journal) Gent, D.H., De Wolf, E., Pethybridge, S.J. 2011. Perceptions of risk, risk aversion, and barriers to adoption of decision support systems and integrated pest management: An introduction. Phytopathology. 101:640-643.Characterization of the spatiotemporal attributes of Sclerotinia flower blight epidemics in a perennial pyrethrum pathosystem-(Peer Reviewed Journal) Pethybridge, S.J., Hay, F.S., Gent, D.H. 2010. Characterization of the spatiotemporal attributes of Sclerotinia flower blight epidemics in a perennial pyrethrum pathosystem. Plant Disease. 94:1305-1313.Characterization of the spatiotemporal attributes of Sclerotinia flower blight epidemics in a perennial pyrethrum pathosystem-(Peer Reviewed Journal)QTL Mapping of Powdery Mildew Susceptibility in Hop (Humulus lupulus L)-(Peer Reviewed Journal) Henning, J.A., Townsend, M.S., Gent, D.H., Bassil, N.V., Matthews, P., Buck, E., Beaston, R. 2011. QTL Mapping of Powdery Mildew Susceptibility in Hop (Humulus lupulus L). Euphytica. 180:411-420.Forecasting and management of hop downy mildew-(Peer Reviewed Journal) Gent, D.H., Ocamb, C.M., Farnsworth, J.L. 2010. Forecasting and management of hop downy mildew. Plant Disease. 94:425-431.Forecasting and management of hop downy mildew-(Peer Reviewed Journal) Gent, D.H., Ocamb, C.M., Farnsworth, J.L. 2010. Forecasting and management of hop downy mildew. Plant Disease. 94:425-431.Prediction of infection risk of hop by Pseudoperonspora humuli-(Peer Reviewed Journal) Gent, D.H., Ocamb, C.M. 2009. Prediction of infection risk of hop by Pseudoperonspora humuli. Phytopathology. 99:1190-1198.SYSTEMS APPROACHES TO MANGEMENT OF HOP DOWNY MILDEW-(Proceedings) Gent, D.H., Nelson, M.E., Farnsworth, J.L., Ocamb, C.M., Grove, G.G.  SYSTEMS APPROACHES TO MANGEMENT OF HOP DOWNY MILDEW. Proceedings of the International Hop Growers Scientific Commission. 2009. p. 80-83.PCR detection of Pseudoperonospora humuli in air samples from hop yards-(Peer Reviewed Journal) Gent, D.H., Nelson, M.E., Farnsworth, J.L., Grove, G.G. 2009. PCR detection of Pseudoperonospora humuli in air samples from hop yards. Plant Pathology. p. 1365-1369.Forecast and virtual weather driven plant disease risk modeling system-(Abstract Only) Coop, L., Fox, A., Mahaffee, W.F., Gent, D.H., Pfender, W.F., Thomas, C. 2009. Forecast and virtual weather driven plant disease risk modeling system. American Phytopathological Society Abstracts. p. 873.Site-specific risk factors for ray blight in Tasmanian pyrethrum fields-(Peer Reviewed Journal) Pethybridge, S., Gent, D.H., Esker, P., Turechek, W., Hay, F., Nutter, F. 2009. Site-specific risk factors for ray blight in Tasmanian pyrethrum fields. Plant Disease. 93:299-308.Straw Mulch and Reduced-Risk Pesticide Impacts upon Thrips and Iris yellow spot virus on Western-Grown Onions-(Peer Reviewed Journal) Schwartz, H.F., Gent, D.H., Fichtner, S.M., Hammon, R., Cranshaw, W.S., Mahaffey, L., Camper, M., Otto, K., Mcmillan, M. 2009. Straw Mulch and Reduced-Risk Pesticide Impacts upon Thrips and Iris yellow spot virus on Western-Grown Onions. Southwestern Entomologist. 34(1):13-29.Effect of Temperature on the Sporulation and Infectivity of Podosphaera macularis on Humulus lupulus-(Peer Reviewed Journal) Peetz, A., Mahaffee, W.F., Gent, D.H. 2009. Effect of temperature on the sporulation and infectivity of Podosphaera macularis on Humulus lupulus. Plant Disease. 93:281-286.Effects of Powdery Mildew Fungicide Programs on Twospotted Spider Mite (Acari: Tetranychidae), Hop Aphid (Homoptera: Aphididae), and Their Natural Enemies in Hop Yards-(Peer Reviewed Journal) Gent, D.H., James, D.G., Wright, L.C., Brooks, D.J., Barbour, J.D., Dreves, A.J., Fisher, G.C., Walton, V.M. 2009. Effects of Powdery Mildew Fungicide Programs on Twospotted Spider Mite (Acari: Tetranychidae), Hop Aphid (Homoptera: Aphididae), and Their Natural Enemies in Hop Yards. Journal of Economic Entomology. 102(1):274-286.Downy Mildew-(Book / Chapter) Johnson, D.A., Engelhard, B., Gent, D.H. 2009. Downy Mildew. In: Mahaffee, W.F., Pethybridge, S.J., Gent, D.H., editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press.  p. 18-22.Hop Shoot Proliferation-(Book / Chapter) Solarska, E., Grudzinska, M., Kaminska, M., Sliwa, H., Gent, D.H. 2009. Hop Shoot Proliferation. In: Mahaffee, W.F., Pethybridge, S.J., Gent, D.H., editors. Compendium on Hop Diseases and Pests. St. Paul, MN: APS Press. p.  57.Hop Cultivars and Breeding-(Book / Chapter) Henning, J.A., Pethybridge, S.J., Gent, D.H. 2009. Hop Cultivars and Breeding. In: Mahaffee, W.F., Pethybridge, S.J., Gent, D.H., editors. Compendium on Hop Diseases and Pests. St. Paul, MN: APS Press. p. 11-13.Crown Gall-(Book / Chapter) Gent, D.H., Bull, C.T. 2009. Crown Gall. In: Mahaffee, W.F., Pethybridge, S.J., Gent, D.H., editors. Compendium of  Hop Diseases and Pests. St. Paul, MN: APS Press. P. 55.Crinkle Disease-(Book / Chapter) Gent, D.H., Bull, C.T. 2009. Crinkle Disease. In: Mahaffee, W.F., Pethybridge, S.J., Gent, D.H., editors.  Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p 54.Bacterial Diseases of Minor Importance-(Book / Chapter) Gent, D.H., Bull, C.T. 2009. Bacterial Diseases of Minor Importance. In: Mahaffee, W.F., Pethybridge, S.J., Gent, D.H., editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press.  p. 56.Spatial and Temporal Stability of the Estimated Parameters of the Binary Power Law-(Peer Reviewed Journal) Gent, D.H., Turechek, W., Mahaffee, W.F. 2008. Spatial and Temporal Stability of the Estimated Parameters of the Binary Power Law. Phytopathology. 98:1107-1117.Powdery Mildew Resistant Hop Germplasm Release: 'Kazak 2000'-(Abstract Only) Hummer, K.E., Gent, D.H., Henning, J.A., Mahaffee, W.F., Ocamb, C. 2008. Powdery Mildew Resistant Hop Germplasm Release: 'Kazak 2000' [abstract]. Acta Horticulturae. p.59Injuries Caused by Environmental Factors-(Book / Chapter) Mahaffee, W.F., Pethybridge, S., Gent, D.H. 2009. Injuries caused by environmental factors. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H.  editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p.77-78.Chemical Injury-(Book / Chapter) Gent, D.H., Pethybridge, S., Mahaffee, W.F. 2009. Chemical injury. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H.  editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p. 78-80.Compendium of Hop Diseases and Pests-(Book / Chapter) Mahaffee, W.F., Pethybridge, S.J.,Gent, D.H. editors. 2009.  Compendium of hop diseases and pests. St. Paul, MN: APS Press. 93 p.Nutrient Imbalances-(Book / Chapter) Mahaffee, W.F., Pethybridge, S., Gent, D.H. 2009. Nutrient imbalances. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H.  editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p. 75-77.Powdery Mildew-(Book / Chapter) Mahaffee, W.F., Englhard, B., Gent, D.H. 2009. Powdery mildew. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H.  editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p. 25-31.A Decade of Hop Powdery Mildew in the Pacific Northwest-(Peer Reviewed Journal) Gent, D. H., Nelson, M. E., George, A. E., Grove, G. G., Mahaffee, W. F., Ocamb, C. M., Barbour, J. D., Peetz, A., and Turechek, W. W. 2008. A decade of hop powdery mildew in the pacific northwest. Online. Plant Health Progress doi:10.1094/PHP-2008-0314-01-RV.Persistence of Phenylamide Insensitivity in Pseudoperonospora humuli-(Peer Reviewed Journal) Gent, D.H., Nelson, M.E., Grove, G.G. 2008. Persistence of Phenylamide Insensitivity in Pseudoperonospora humuli. Plant Disease.92(3):463-468.Relationship between Rust Mites, Calepitrimerus vitis (Acari:  Eriophyidae), Bud Mites Colomeris vitis (Acari: Eriophyidae) and Short Shoot Syndrome in Oregon Vineyards-(Peer Reviewed Journal) Walton, V.M., Dreves, A., Gent, D.H., James, D.G., Martin, R.R., Chambers, U., Skinkis, P.A. 2007. Relationship between rust mites, Calepitrimerus vitis (Acari:  Eriophyidae), bud mites Colomeris vitis (Acari: Eriophyidae) and short shoot syndrome in Oregon vineyards. International Journal of Acarology. 33:307-318.Registration of 'Teamaker' Hop-(Peer Reviewed Journal) Henning, J.A., Haunold, A., Townsend, M.S., Gent, D.H., Parker, T. 2008. Registration of 'Teamaker' Hop. Journal of Plant Registrations.2(1):13-14.Sequential sampling for estimation and classification of the incidence of hop powdery mildew II:  Cone sampling-(Peer Reviewed Journal) Gent, D.H., Turechek, W., Mahaffee, W.F. 2007. Sequential sampling for estimation and classification of the incidence of hop powdery mildew II:  Cone sampling. Plant Disease. 91:1013-1020.Sequential sampling for estimation and classification of the incidence of hop powdery mildew I: Leaf sampling-(Peer Reviewed Journal) Gent, D.H., Turechek, W., Mahaffee, W.F. 2007. Sequential sampling for estimation and classification of the incidence of hop powdery mildew I: Leaf sampling. Plant Disease. 91:1002-1012.First Report of Iris yellow spot virus on Onion and Leek in Western Oregon-(Peer Reviewed Journal) Gent, D.H., Martin, R.R., Ocamb, C.M. 2007. First Report of Iris yellow spot virus on Onion and Leek in Western Oregon. Plant Disease. V91: P 468.Iris yellow spot virus: An emerging threat to onion bulb and seed production-(Peer Reviewed Journal) Gent, D.H., Du Toit, L.J., Fichtner, S.F., Mohan, S.K., Pappu, H.R., Schwartz, H.F. 2006. Iris yellow spot virus: An emerging threat to onion bulb and seed production. Plant Disease.Spatial Heterogeneity of the Incidence of Powdery Mildew on Hop Cones-(Peer Reviewed Journal) Gent, D.H., Mahaffee, W.F., Turechek, W. 2006. Spatial Heterogeneity of the Incidence of Powdery Mildew on Hop Cones. Plant Disease.AN UPDATE ON XANTHOMONAS LEAF BLIGHT-(Trade Journal) Schwartz, H.F., Gent, D.H. 2005. An update on xanthomonas leaf blight. Onion World.p. 26-28.MORE ON IRIS YELLOW SPOT-(Trade Journal) Schwartz, H.F., Gent, D.H., Fichtner, S. 2005. More on iris yellow spot. Onion World. p. 6-9.XANTHOMONAS LEAF BLIGHT OF ONION-(Experiment Station) Schwartz, H.F., Gent, D.H. 2005. Xanthomonas leaf blight of onion. Extension Publications. Diseases. No. 2.951.EFFECT OF NITROGEN FERTILIZATION AND SEED CONTAMINATION ON EPIPHYTIC POPULATIONS OF XANTHOMONAS AXONOPODIS PV. ALLII AND DEVELOPMENT OF XANTHOMONAS LEAF BLIGHT OF ONION-(Peer Reviewed Journal)MANAGEMENT OF XANTHOMONAS LEAF BLIGHT OF ONION WITH A PLANT ACTIVATOR, BIOLOGICAL CONTROL AGENTS, AND COPPER BACTERICIDES-(Peer Reviewed Journal)HIGH PLAINS INTEGRATED PEST MANAGEMENT GUIDE-(Other) Schwartz, H.F., Gent, D.H. 2004. Bacterial leaf spot. Online Guide: High Plains Integrated Pest Management Guide. Available at: www.highplainsIPM.org.EPIPHYTIC SURVIVAL OF XANTHOMONAS AXONOPODIS PV. ALLII AND X. AXONOPODIS PV. PHASEOLI ON LEGUMINOUS HOSTS AND ONION-(Peer Reviewed Journal)  ARS News ArticlesNo news articles listed for this employee.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov