Research Project: Breeding, Genomics, and Integrated Pest Management to Enhance Sustainability of U.S. Hop Production and Competitiveness in Global Markets

Location: Forage Seed and Cereal Research Unit

Publications (Clicking on the reprint icon will take you to the publication reprint.)

Evaluating the effects of reduced late-season irrigation on fry color of five processing potato cultivars - (Peer Reviewed Journal)
Gonzalez Tapia, F., Pavek, M.J., Knowles, R.N., Holden, Z. 2024. Evaluating the effects of reduced late-season irrigation on fry color of five processing potato cultivars. Potato Research. https://doi.org/10.1007/s12230-024-09948-4.

An affordable and convenient diagnostic marker to identify male and female hop plants - (Peer Reviewed Journal)
Clare, S.J., King, R., Tawril, A., Havill, J.S., Muehlbauer, G.J., Carey, S., Harkess, A., Bassil, N.V., Altendorf, K.R. 2023. An affordable and convenient diagnostic marker to identify male and female hop plants. G3, Genes/Genomes/Genetics. 14(1). Article jkad216. https://doi.org/10.1093/g3journal/jkad216.

Plant disease warning systems - (Book / Chapter)

HopBox: An image analysis pipeline to characterize hop cone morphology - (Peer Reviewed Journal)
Altendorf, K.R., Heineck, G.C., Wakholi, C., Tawril, A., Raja, P., Rippner, D.A. 2023. HopBox: An image analysis pipeline to characterize hop cone morphology. The Plant Phenome Journal. 6(1). Article e20080. https://doi.org/10.1002/ppj2.20080.

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.

Evaluating potato evapotranspiration and crop coefficients in the Columbia basin of Washington state - (Peer Reviewed Journal)
Gonzalez Tapia, F., Pavek, M.J., Holden, Z., Garza, R. 2023. Evaluating potato evapotranspiration and crop coefficients in the Columbia basin of Washington state. Agricultural Water Management. Volume 286. https://doi.org/10.1016/j.agwat.2023.108371.

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.

Nontraditional production additives fail to improve potato yield and economic return - (Peer Reviewed Journal)
Thurgood, C., Gonzalez Tapia, F., Holden, Z., Pavek, M.J. 2022. Nontraditional production additives fail to improve potato yield and economic return. Agronomy Journal. Volume 115, Issue 2, Page 801-816. https://doi.org/10.1002/agj2.21259.

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.

An improved assembly of the “Cascade” hop (Humulus lupulus) genome uncovers signatures of molecular evolution and refines time of divergence estimates for the Cannabaceae family - (Peer Reviewed Journal)
Padgitt-Cobb, L.K., Pitra, N.J., Matthews, P.D., Henning, J.A., Hendrix, D.A. 2022. An improved assembly of the “Cascade” hop (Humulus lupulus) genome uncovers signatures of molecular evolution and refines time of divergence estimates for the Cannabaceae family. Horticulture Research. 10(2). Article uhac281. https://doi.org/10.1093/hr/uhac281.

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.

Genetic architecture of yield-component traits in the new perennial grain crop intermediate wheatgrass - (Peer Reviewed Journal)
Altendorf, K.R., DeHaan, L.R., Anderson, J.A. 2022. Genetic architecture of yield-component traits in the new perennial grain crop intermediate wheatgrass. Crop Science. 62(2):880-892. https://doi.org/10.1002/csc2.20716.

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.

Gene expression of agronomically important secondary metabolites in cv. ‘USDA Cascade’ hop (Humulus lupulus L.) cones during critical developmental stages - (Peer Reviewed Journal)
Eriksen, R.L., Padgitt-Cobb, L.K., Randazzo, A., Hendrix, D., Henning, J.A. 2021. Gene expression of agronomically important secondary metabolites in cv. ‘USDA Cascade’ hop (Humulus lupulus L.) cones during critical developmental stages. Journal of the American Society of Brewing Chemists. https://doi.org/10.1080/03610470.2021.1973328.

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.

The long-read genome assembly of hop (Humulus lupulus) uncovers the pseudoautosomal region and other genomic features - (Peer Reviewed Journal)
Padgitt-Cobb, L.K., Kothen-Hill, S.T., Henning, J.A., Hendrix, D.A. 2021. The long-read genome assembly of hop (Humulus lupulus) uncovers the pseudoautosomal region and other genomic features. Acta Horticulturae. 1328. https://doi.org/10.17660/ActaHortic.2021.1328.1.

QTL for seed shattering and threshability in intermediate wheatgrass align closely with well-studied orthologs from wheat, barley, and rice - (Peer Reviewed Journal)
Altendorf, K.R., DeHaan, L.R., Larson, S.R., Anderson, J.A. 2021. QTL for seed shattering and threshability in intermediate wheatgrass align closely with well-studied orthologs from wheat, barley, and rice. The Plant Genome. 14(3). Article e20145. https://doi.org/10.1002/tpg2.20145.

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.

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.

Gene expression for secondary metabolite biosynthesis in hop (Humulus lupulus L.) leaf lupulin glands exposed to heat and low-water stress - (Peer Reviewed Journal)
Eriksen, R.L., Padgitt-Cobb, L., Townsend, M., Henning, J.A. 2021. Gene expression for secondary metabolite biosynthesis in hop (Humulus lupulus L.) leaf lupulin glands exposed to heat and low-water stress. Scientific Reports. 11. Article 5138. https://doi.org/10.1038/s41598-021-84691-y.

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.

Floret site utilization and reproductive tiller number are primary components of yield in intermediate wheatgrass spaced plants - (Peer Reviewed Journal)
Altendorf, K.R., Dehaan, L.R., Heineck, G.C., Zhang, X., Anderson, J.A. 2020. Floret site utilization and reproductive tiller number are primary components of yield in intermediate wheatgrass spaced plants. Crop Science. 61(2):1073-1088. https://doi.org/10.1002/csc2.20385.

A draft phased assembly of the diploid Cascade hop (Humulus lupulus) genome - (Peer Reviewed Journal)
Padgitt-Cobb, L.K., Kingan, S.B., Wells, J., Elser, J., Kronmiller, B., Moore, D.L., Concepcion, G., Peluso, P., Rank, D., Jaiswal, P., Henning, J.A., Hendrix, D.A. 2021. A draft phased assembly of the diploid Cascade hop (Humulus lupulus) genome. The Plant Genome. 14(1). Article e20072. https://doi.org/10.1002/tpg2.20072.

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.

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.

Photosynthetic activity of six hop (Humulus lupulus L.) cultivars under different temperature treatments - (Peer Reviewed Journal)
Eriksen, R.L., Rutto, L.K., Dombrowski, J.E., Henning, J.A. 2020. Photosynthetic activity of six hop (Humulus lupulus L.) cultivars under different temperature treatments. HortScience. 55(4):403-409. https://doi.org/10.21273/HORTSCI14580-19.

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.

Genomic analysis of powdery mildew resistance in a hop (Humulus lupulus L.) bi-parental population segregating for “R6-locus” - (Peer Reviewed Journal)
Padgitt-Cobb, L., Kingan, S.B., Henning, J.A. 2019. Genomic analysis of powdery mildew resistance in a hop (Humulus lupulus L.) bi-parental population segregating for “R6-locus”. Euphytica. 216:10. https://doi.org/10.1007/s10681-019-2543-x.

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.

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.