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                    U.S. DEPARTMENT OF AGRICULTURE
 Horticultural Crops Disease and Pest Management Research Unit: Corvallis, OR
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Walter F Mahaffee

(Walt)    Research Plant Pathologist /ARSUserFiles/3536/walt 1.jpg 3420 NW Orchard Ave Corvallis, OR 97330 (541) 738-4036
 Research focuses on understanding the ecology of microorganisms on plant surfaces, and applying that knowledge to reduce disease development in agronomic settings while enhancing the economic and sustainable production of horticultural crops. Current projects include; (1) characterize the biology of foliar and fruit pathogens, particularly powdery mildews and *Botrytis cinerea*; (2) developing methods to detect and monitor airborne inoculum and use of these data as a decision aid for disease management; (3) model turbulent airflow and spore dispersion to better predict the spatial and temporal spread of a pathogen; (4) assessment and mitigation of fungicide resistance.
 ProjectsKnowledge Based Tools for Exotic and Emerging Diseases of Small Fruit and Nursery CropsIn-House Appropriated (D)Accession Number:442138Developing a Spray-Induced Gene Silencing (SIGS) Method for the Control of Grape Powdery Mildew (Erysiphe necator)Grant (G)Accession Number:437078Fungal Microbiome Associated with Grapevine Trunk Diseases in Oregon VineyardsGrant (G)Accession Number:439677Evaluation of Novel Cold Hardy Grape Rootstocks for Use in the Pacific NorthwestGrant (G)Accession Number:442748Biological Fungicides Tank Mixed with Sulfur for Management of Grape Powdery MildewGrant (G)Accession Number:444960A Systems Approach for Managing Bacterial Blight of CarrotReimbursable Cooperative Agreement (R)Accession Number:439438TomSPOT - an Integrated Toolbox for Managing Tomato Bacterial Diseases in North AmericaReimbursable Cooperative Agreement (R)Accession Number:442346Development of Hazelnuts for Resistance to Eastern Filbert BlightNon-Assistance Cooperative Agreement (S)Accession Number:437013Whole Genome Sequencing for Epidemiology, Population Structure, and Fungicide Resistance of Botrytis spp. in the Pacific NorthwestNon-Assistance Cooperative Agreement (S)Accession Number:445131Model Based Evaluation of Grape Vineyard Exposure to Wildfire SmokeNon-Assistance Cooperative Agreement (S)Accession Number:445758  Publications(Clicking on the reprint iconReprint Icon  will take you to the publication reprint.)Identification of a receptor for the sex pheromone of the vine mealybug, Planococcus ficus-(Peer Reviewed Journal) Corcoran, J., Mahaffee, W.F. 2024. Identification of a receptor for the sex pheromone of the vine mealybug, Planococcus ficus. Current Research in Insect Science. https://doi.org/10.1016/j.cris.2024.100072.Adding stability classes and new interpolation schemes to improve modeling wind over complex topography-(Abstract Only) Bozorgmehr, B., Margairaz, F., Stoll, R., Mahaffee, W.F., Lee, J., Liu, H. 2023. Adding stability classes and new interpolation schemes to improve modeling wind over complex topography [abstract]. American Geophysical Union.A rapid glove-based inoculum sampling technique to monitor Erysiphe necator in commercial vineyards-(Peer Reviewed Journal) Lowder, S.R., Neill, T.M., Peetz, A., Miles, T.M., Moyer, M.M., Oliver, C., Stergiopoulos, I., Ding, S., Mahaffee, W.F. 2023. A rapid glove-based inoculum sampling technique to monitor Erysiphe necator in commercial vineyards. Plant Disease. https://doi.org/10.1094/PDIS-02-23-0216-RE.A chromosome-scale genome assembly of the grape powdery mildew pathogen Erysiphe necator reveals its genomic architecture and previously unknown features of its biology-(Peer Reviewed Journal) Zaccaron, A.Z., Neill, T.M., Corcoran, J., Mahaffee, W.F., Stergiopoulos, I. 2023. A chromosome-scale genome assembly of the grape powdery mildew pathogen Erysiphe necator reveals its genomic architecture and previously unknown features of its biology. mBio. Article e00645-23. https://doi.org/10.1128/mbio.00645-23.Development of a PNA-LNA-LAMP assay to detect a SNP associated with QoI resistance in Erysiphe necator-(Peer Reviewed Journal)Improving accuracy of a microscale fast-response wind modeling platform (QES-Winds) by downscaling wind data from a mesoscale numerical weather prediction model (HRRR)-(Abstract Only)A fast-response, wind angle-sensitive model for predicting mean winds in row-organized canopies-(Peer Reviewed Journal) Ulmer, L., Margairaz, F., Bailey, B., Mahaffee, W.F., Pardyjak, E., Stoll, R. 2022. A fast-response, wind angle-sensitive model for predicting mean winds in row-organized canopies. Agricultural and Forest Meteorology. 329. Article 109273. https://doi.org/10.1016/j.agrformet.2022.109273.Catching spores: Linking epidemiology, pathogen biology, and physics to ground-based airborne inoculum monitoring-(Peer Reviewed Journal) Mahaffee, W.F., Margairaz, F., Ulmer, L., Bailey, B.N., Stoll, R. 2023. Catching spores: Linking epidemiology, pathogen biology, and physics to ground-based airborne inoculum monitoring. Plant Disease. 107(1):13-33. https://doi.org/10.1094/PDIS-11-21-2570-FE.Quantifying turbulence heterogeneity in a vineyard using eddy-covariance and scintillometer measurements-(Peer Reviewed Journal) Perelet, A.O., Ward, H.C., Stoll, R., Mahaffee, W.F., Pardyjak, E. 2022. Quantifying turbulence heterogeneity in a vineyard using eddy-covariance and scintillometer measurements. Boundary Layer Meteorology. 184:479-504. https://doi.org/10.1007/s10546-022-00714-9.Identification of putative SDHI target site mutations in the SDHB, SDHC, and SDHD subunits of the grape powdery mildew pathogen Erysiphe necator-(Peer Reviewed Journal) Stergiopoulos, I., Aoun, N., Huynh, Q., Neill, T.M., Lowder, S., Newbold, C., Cooper, M.L., Ding, S., Moyer, M., Miles, T.D., Oliver, C.L., Urbez-Torres, J., Mahaffee, W.F. 2022. Identification of putative SDHI target site mutations in the SDHB, SDHC, and SDHD subunits of the grape powdery mildew pathogen Erysiphe necator. Molecular Plant Pathology. 106(9):2310-2320. https://doi.org/10.1094/PDIS-09-21-1993-RE.Esca and young vine decline-(Book / Chapter) Baumgartner, K., Mahaffee, W.F. 2022. Esca and young vine decline. In: Moyer, M.M., O'Neal, S.D., editors. Field Guide for Integrated Pest Management in Pacific Northwest Vineyards. 2nd edition. Pacific Northwest Extension Publication #PNW644. Pullman, WA: Washington State University Press. p. 89-91.Adaption and validation of a voxel based energy transport model for conifer species-(Peer Reviewed Journal) Moody, M.J., Bailey, B.N., Pardyjak, E., Mahaffee, W.F., Stoll, R. 2021. Adaption and validation of a voxel based energy transport model for conifer species. Urban Climate. 39. Article 100967. https://doi.org/10.1016/j.uclim.2021.100967.Assessing the United States grape industry’s understanding of fungicide resistance mitigation practices-(Peer Reviewed Journal) Oliver, C.L., Cooper, M., Lewis-Ivey, M.L., Brannen, P., Miles, T., Mahaffee, W.F., Moyer, M.M. 2021. Assessing the wine grape industry’s understanding of fungicide resistance mitigation practices for grapevine powdery mildew (erysiphe necator) in the United States. American Journal of Enology and Viticulture. 72(2):181-193. https://doi.org/10.5344/ajev.2021.20062.Allele-specific detection methods for QoI fungicide resistant Erysiphe necator in vineyards-(Peer Reviewed Journal) Miles, T.D., Neill, T.M., Colle, M., Warneke, B., Robinson, G., Stergiopoulos, I., Mahaffee, W.F. 2020. Allele-specific detection methods for QoI fungicide resistant Erysiphe necator in vineyards. Plant Disease. https://doi.org/10.1094/PDIS-11-19-2395-RE.Effect of fungicide mobility and application timing on the management of grape powdery mildew-(Peer Reviewed Journal) Warneke, B., Thiessen, L., Mahaffee, W.F. 2020. Effect of fungicide mobility and application timing on the management of grape powdery mildew. Plant Disease. 104(3):1167-1174. https://doi.org/10.1094/PDIS-06-19-1285-RE.Formation of Erysiphe necator Chasmothecia in the Pacific Northwest United States-(Peer Reviewed Journal) Thiessen, L.D., Neill, T.M., Mahaffee, W.F. 2019. Formation of Erysiphe necator Chasmothecia in the Pacific Northwest United States. Plant Disease. 103(5):890-896. https://doi.org/10.1094/PDIS-06-18-1012-RE.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.Drosophila suzukii flight performance reduced by starvation but not affected by humidity-(Peer Reviewed Journal) Wong, J., Cave, A., Lightle, D., Mahaffee, W.F., Naranjo, S.E., Wiman, N., Woltz, M., Lee, J.C. 2018. Drosophila suzukii flight performance reduced by starvation but not affected by humidity. Journal of Pest Science. 91(4):1269-1278. https://doi.org/10.1007/s10340-018-1013-x.Interruption and reduction of Erysiphe necator cleistothecia development utilizing fungicidal oil-(Peer Reviewed Journal) Thiessen, L., Neill, T.M., Mahaffee, W.F. 2018. Interruption and reduction of Erysiphe necator cleistothecia development utilizing fungicidal oil. Plant Health Progress. 19:153-155. https://doi.org/10.1094/php-11-17-0070-rs.Heavy particle transport in a trellised agricultural canopy during non-row-aligned winds-(Peer Reviewed Journal) Miller, N., Stoll, R., Mahaffee, W.F., Neill, T.M. 2018. Heavy particle transport in a trellised agricultural canopy during non-row-aligned winds. Agricultural and Forest Meteorology. 256-257:125-136. https://doi.org/10.1016/j.agrformet.2018.02.032.Assessment of Erysiphe necator ascospore release models for use in the Mediterranean climate of western Oregon-(Peer Reviewed Journal) Thiessen, L., Neill, T.M., Mahaffee, W.F. 2018. Assessment of Erysiphe necator ascospore release models for use in the Mediterranean climate of western Oregon. Plant Disease. 102(8):1500-1508. https://doi.org/10.1094/PDIS-10-17-1686-RE.Development of a quantitative loop-mediated isothermal amplification assay for the field detection of Erysiphe necator-(Peer Reviewed Journal) Thiessen, L.D., Neill, T.M., Mahaffee, W.F. 2018. Development of a quantitative loop-mediated isothermal amplification assay for the field detection of Erysiphe necator. PeerJ. 6:e4639. https://doi.org/10.7717/peerj.4639.Mean and turbulent flow statistics in a trellised agricultural canopy-(Peer Reviewed Journal) Miller, N., Stoll, R., Mahaffee, W.F., Pardyjak, E. 2017. Mean and turbulent flow statistics in a trellised agricultural canopy. Boundary Layer Meteorology. doi: 10.1007/s10546-017-0265-y.Timing fungicide application intervals based on airborne Erysiphe necator concentrations-(Peer Reviewed Journal) Thiessen, L.D., Neill, T.M., Mahaffee, W.F. 2017. Timing fungicide application intervals based on airborne Erysiphe necator concentrations. Phytopathology. 101(7):1246-1252. doi: 10.1094/PDIS-12-16-1727-RE.Rapid measurement of the three-dimensional distribution of leaf orientation and the leaf angle probability density function using terrestrial LiDAR scanning-(Peer Reviewed Journal) Bailey, B.N., Mahaffee, W.F. 2017. Rapid measurement of the three-dimensional distribution of leaf orientation and the leaf angle probability density function using terrestrial LiDAR scanning. Remote Sensing of Environment. 194(2017):63-76. doi: 10.1016/j.rse.2017.03.011.Rapid, high-resolution measurement of leaf area and leaf orientation using terrestrial LiDAR scanning data-(Peer Reviewed Journal) Bailey, B.N., Mahaffee, W.F. 2017. Rapid, high-resolution measurement of leaf area and leaf orientation using terrestrial LiDAR scanning data. Measurement Science and Technology. 28(6):064006. doi: 10.1088/1361-6501/aa5cfd.Early detection of airborne inoculum of Magnaporthe oryzae in turfgrass fields using a quantitative LAMP assay-(Peer Reviewed Journal) Villari, C., Mahaffee, W.F., Mitchell, T.K., Pedley, K.F., Pieck, M.L., Peduto Hand, F. 2017. Early detection of airborne inoculum of Magnaporthe oryzae in turfgrass fields using a quantitative LAMP assay. Plant Disease. 101(1):170-177. doi: 10.1094/PDIS-06-16-0834-RE.Detection and quantification of Bremia lactucae by spore trapping and quantitative PCR-(Peer Reviewed Journal) Kunjeti, S.G., Anchieta, A.G., Martin, F.N., Choi, Y.-J., Thines, M., Michelmore, R.W., Koike, S.T., Tsuchida, C., Mahaffee, W.F., Subbarao, K.V., Klosterman, S.J. 2016. Detection and quantification of Bremia lactucae by spore trapping and quantitative PCR. Phytopathology. 106:1426-1437.The ebb and flow of airborne pathogens: Monitoring and use in disease management decisions-(Peer Reviewed Journal) Mahaffee, W.F., Stoll, R. 2016. The ebb and flow of airborne pathogens: Monitoring and use in disease management decisions. Phytopathology. 106(5):420-431. doi: 10.1094/PHYTO-02-16-0060-RVW.An experimental study of momentum and heavy particle transport in a trellised agricultural canopy-(Peer Reviewed Journal) Miller, N., Stoll, R., Mahaffee, W.F., Neill, T.M., Pardyjak, E.R. 2015. An experimental study of momentum and heavy particle transport in a trellised agricultural canopy. Agriculture and Forest Meterology. 211-212:100-114.Development of a quantitative loop-mediated isothermal amplification (qLAMP) assay for the detection of Magnaporthe oryzae airborne inoculum in turf ecosystems-(Abstract Only) Villari, C., Mahaffee, W.F., Mitchell, T.K., Pedley, K.F., Pieck, M.L., Peduto Hand, F. 2015. Development of a quantitative loop-mediated isothermal amplification (qLAMP) assay for the detection of Magnaporthe oryzae airborne inoculum in turf ecosystems. In: Poster sessions of the American Phytopathological Society Annual Meeting. August 1-5, 2015, Pasadena, California. 443-P.Development of a grower performed inoculum detection assay for management of grape powdery mildew-(Peer Reviewed Journal) Thiessen, L.D., Keune, J.A., Neill, T.M., Turechek, W., Grove, G., Mahaffee, W.F. 2015. Development of a grower performed inoculum detection assay for management of grape powdery mildew. Plant Pathology. 65:238–249. doi: 10.1111/ppa.12421A scalable plant-resolving radiative transfer model based on optimized GPU ray tracing-(Peer Reviewed Journal) Bailey, B., Overby, M., Willemsen, P., Pardyjak, E.R., Mahaffee, W.F., Stoll, R. 2014. A scalable plant-resolving radiative transfer model based on optimized GPU ray tracing. Agriculture and Forest Meterology. 198-199:192-208. doi.org/10.1016/j.agrformet.2014.08.012.Effect of vegetative canopy architecture on vertical transport of massless particles-(Peer Reviewed Journal) Bailey, B.N., Stoll, R., Pardyjak, E.R., Mahaffee, W.F. 2014. Effect of vegetative canopy architecture on vertical transport of massless particles. Atmospheric Environment. 95:480-489.Improving management of grape powdery mildew with new tools and knowledge-(Review Article) Mahaffee, W.F., Schwebs, S., Hand, F., Gubler, D., Baily, B., Stoll, R. 2014. Improving management of grape powdery mildew with new tools and knowledge. Practical Winery and Vineyards. April:59-67.Use of airborne inoculum detection for disease management decisions-(Book / Chapter) Mahaffee, W.F. 2014. Use of airborne inoculum detection for disease management decisions. In: Gullino, M.L., Bonants, P.J.M., editors. Detection and Diagnostics of Plant Pathogens. New York, NY: Springer. p. 39-54.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.Invaded range of the blackberry pathogen Phragmidium violaceum in the Pacific Northwest of the USA and the search for its provenance-(Peer Reviewed Journal) Morin, L., Gomez, D., Evans, K., Neill, T.M., Mahaffee, W.F., Linde, C. 2013. Invaded range of the blackberry pathogen Phragmidium violaceum in the Pacific Northwest of the USA and the search for its provenance. Biological Invasions. 15(8):1847-1861.Eutypa canker and dieback-(Experiment Station) Mahaffee, W.F., Grove, G. 2013. Eutypa canker and dieback. Pacific Northwest Grape IMP Manual.Powdery mildew-(Book / Chapter) Mahaffee, W.F., Glawe, D. 2014. Powdery mildew. In: Linderman, R.G., Benson, D.M., editors. Compendium of Rhododendron and Azalea Diseases and Pests. 2nd edition. St. Paul, MN: The American Phytopathological Society Press. p. 41-44.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.Is it tea time?-(Popular Publication) Mahaffee, W.F. 2012. Is it tea time? Pennsylvania Landscape and Nursery. March/April 2012 Issue.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.Inoculum detection for managing grape powdery mildew-(Popular Publication) Mahaffee, W.F., Grove, G., Stoll, R. 2011. Inoculum detection for managing grape powdery mildew. Practical Winery and Vineyards. Spring. p. 26-32.Subsurface examination of a foliar biofilm using scanning electron- and focused-ion-beam microscopy-(Peer Reviewed Journal) Wallace, P., Arey, B., Mahaffee, W.F. 2011. Subsurface examination of a foliar biofilm using scanning electron- and focused-ion-beam microscopy. Micron. 42:579-585.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.The impact of canopy geometry on particle dispersion gradients in sparse agricultural canopies-(Proceedings) Bailey, B., Stoll, R., Mahaffee, W.F., Pardyjak, E. 2010. The impact of canopy geometry on particle dispersion gradients in sparse agricultural canopies. Agricultural and Forest Meteorology Conference Proceedings. Available: http://ams.confex.com/ams/19Ag19BLT9Urban/techprogram/MEETING.HTM.Permanent Genetic Resources added to Molecular Ecology Resources Database 1 December 2009–31 January 2010-(Peer Reviewed Journal) C., Gomez, D., Morin, L., Evans, K., Mahaffee, W.F., Neill, T.M., Grunwald, N.J.,Molecular Ecology Resources Primer Development Consortium. 2010. Permanent genetic resources added to molecular ecology resources database 1 December 2009–31 January 2010. Molecular Ecology Resources. 10:576-579.Development of 11 polymorphic microsatellite markers for the blackberry rust fungus Phragmidium violaceum-(Peer Reviewed Journal) Gomez, D., Morin, L., Evans, K., Mahaffee, W.F., Neill, T.M., Grunwald, N.J. 2010. Development of 11 polymorphic microsatellite markers for the blackberry rust fungus Phragmidium violaceum. Molecular Ecology Resources. 10:576-579.Factors Influencing Epidemiology and Management of Blackberry Rust in Cultivated Rubus laciniatus-(Peer Reviewed Journal) Johnson, K., Mahaffee, W.F. 2010. Factors influencing epidemiology and management of blackberry rust in cultivated Rubus laciniatus. Plant Disease. 94:581-588.Development and Use of Fluorescent Antibody and qPCR Protocols for the Electrostatic Spore Trap-(Abstract Only) Schneider, R.W., Haudenshield, J.S., Hartman, G.L., Mahaffee, W.F. 2010. Development and Use of Fluorescent Antibody and qPCR Protocols for the Electrostatic Spore Trap [abstract]. American Phytopathological Society National Meeting, August 1-5, 2009, Portland, Oregon. 99:S115.Foliar biofilms of Burkholderia pyrrocinia FP62 on geraniums-(Abstract Only) Wallace, P., Mahaffee, W.F., Neill, T.M. 2009. Foliar biofilms of Burkholderia pyrrocinia FP62 on geraniums. American Phytopathological Society Abstracts. p. 568.The relationship of biofilm production to biocontrol activity of Burkholderia pyrrocinia FP62-(Abstract Only) Wallace, P., Mahaffee, W.F., Press, C.M., Larsen, M.M., Neill, T.M. 2009. The relationship of biofilm production to biocontrol activity of Burkholderia pyrrocinia FP62. American Phytopathological Society Abstracts. p. 569.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.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.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.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.The Genus Humulus-(Book / Chapter) Mahaffee, W.F., Pethybridge, S. 2009. The genus Humulus. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H.  editors.  Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p. 1-5.Cone Early Maturity-(Book / Chapter) Mahaffee, W.F. 2009. Cone early maturity. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H.  editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p. 73-74.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.Cone Early Maturity-(Book / Chapter)Gray Mold-(Book / Chapter) Mahaffee, W.F., Englhard, B. 2009. Gray mold. In: Mahaffee, W.F., Pethybridge, S.J., and Gent, D.H.  editors. Compendium of Hop Diseases and Pests. St. Paul, MN: APS Press. p. 24-25.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.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.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.DETECTION OF ERYSIPHE (UNCINULA) NECATOR USING THE POLYMERASE CHAIN REACTION AND SPECIES-SPECIFIC PRIMERS-(Peer Reviewed Journal) Falacy, J. S., Grove, G. G., Mahaffee, W. F., Galloway, H., Glawe, D. A., Larsen, R. C., and Vandermark, G. J. 2007. Detection of Erysiphe necator in air samples using the polymerase chain reaction and species-specific primers. Phytopathology 97:1290-1297.Variability Associated with Suppression of Gray Mold (Botrytis cinerea) on Geranium (Pelargonium x hortorum) by Foliar Applications of Non-Aerated and Aerated Compost Teas-(Peer Reviewed Journal) Scheuerell, S., Mahaffee, W.F. 2006. Variability associated with suppression of gray mold (Botrytis cinerea) on geranium (Pelargonium x hortorum) by foliar applications of non-aerated and aerated compost teas. Plant Disease.  90:1201-1208.Compost Teas: Alternatives to Traditional Biological Control Agents-(Book / Chapter) Mahaffee, W.F. and Scheuerell, S. 2006. Compost teas: Alternatives to traditional biological control agents. In: Baily, M.J., Lilley, A.K., Timms-Wilson, T.M., and Spencer-Phillips, P.T.N. editors.  Microbial Ecology of Aerial Plant Surfaces. Oxford, England: CABI. p.165-179.ATYPICAL DISEASE RESPONSE TO HOP POWDERY MILDEW-(Abstract Only) Smith, J.M., Hummer, K.E., Mahaffee, W.F. 2005. Atypical disease response to hop powdery mildew [abstract]. Hortscience.  40(4):1034.DETECTION OF PODOSPHAERA CLANDESTINE IN THE AIR OF CHERRY ORCHARDS USING PCR AND SPECIES-SPECIFIC PRIMERS-(Abstract Only) Grove, G.G., Galloway, H., Lunden, J., Spotts, R.A., Mahaffee, W.F. 2005. Detection of podosphaera clandestine in the air of cherry orchards using pcr and species-specific primers. Phytopathology.QUANTIFICATION OF AIRBORNE HOP POWDERY MILDEW INOCULUM, A MOLECULAR APPROACH.-(Abstract Only) Peetz, A.B., Mahaffee, W.F., Grove, G.G. 2005. Quantification of airborne hop powdery mildew inoculum, a molecular approach.. Phytopathology.THE RISE AND FALL OF HOP POWDERY MILDEW IN THE PACIFIC NORTHWEST-(Abstract Only) Mahaffee, W.F., Turechek, W., Thomas, C.S., Grove, G.G., Galloway, H., Nelson, M., Ocamb, C.M. The rise and fall of hop powdery mildew in the pacific northwest. Phytopathology.RAPID DETECTION AND QUANTIFICATION OF AIRBORNE HOP POWDERY MILDEW INOCULUM-(Abstract Only) Peetz, A.B., Mahaffee, W.F., Jackson, J., Grove, G.G., Galloway, H. 2005. Rapid detection and quantification of airborne hop powdery mildew inoculum. Phytopathology. 95:S81.DETECTION OF ERYSIPHE NECATOR IN THE AIR OF GRAPE VINEYARDS IN EASTERN WASHINGTON-(Abstract Only) Grove, G.G., Falacy, J., Galloway, H., Mahaffee, W.F., Turechek, W., Peetz, A.B. 2005. Detection of erysiphe necator in the air of grape vineyards in eastern washington. Phytopathology. 95:S36.SUPPRESSION OF SEEDLING DAMPING-OFF CAUSED BY PYTHIUM ULTIMUM, PYTHIUM IRREGULARE, AND RHIZOCTONIA SOLANI IN CONTAINER MEDIA AMENDED WITH A DIVERSE RANGE OF PACIFIC NORTHWEST COMPOST SOURCES-(Peer Reviewed Journal) Scheuerell, S.J., Sullivan, D.M., Mahaffee, W.F.,  2005. Suppression of seedling damping-off caused by pythium ultimum, pythium irregulare, and rhizoctonia solani in container media amended with a diverse range of pacific northwest compost sources. Phytopathology.95(3):306-315.HIGH TEMPERATURE-DEPENDENT RESISTANCE TO POWDERY MILDEW IN HOPS-(Abstract Only) Jackson, J., Hummer, K.E., Mahaffee, W.F. 2004. High temperature-dependent resistance to powdery mildew in hops [abstract]. Acta Horticulturae. p. 26.COMPOST TEA AS A CONTAINER MEDIA DRENCH FOR SUPRESSING SEEDLING DAMPING-OFF CAUSED BY PYTHIUM ULTIMUM-(Peer Reviewed Journal) Scheurell, S., Mahaffee, W.F. 2004. Compost tea as a container media drench for supressing seedling damping-off caused by pythium ultimum. Phytopathology.  94(11)1156-1163.SPATIAL PATTERN ANALYSIS OF HOP POWDERY MILDEW IN THE PACIFIC NORTHWEST:  IMPLICATION FOR SAMPLING-(Peer Reviewed Journal) Turechek, W., Mahaffee, W.F. 2004. Spatial pattern analysis of hop powdery mildew in the pacific northwest:  implication for sampling. Phytopathology. 94(10):1116-1128.MICROBIAL RECOLONIZATION OF COMPOST AFTER PEAK HEATING NEEDED FOR THE RAPID DEVELOPMENT OF DAMPING-OFF SUPPRESSION CAUSED BY PYTHIUM ULTIMUM-(Peer Reviewed Journal) Scheuerell, S., Mahaffee, W.F. 2005. Microbial recolonization of compost after peak heating needed for the rapid development of damping-off suppression caused by pythium ultimum. Compost Science and Utilization. 13:65-71.REGISTRATION OF NEWPORT HOP-(Peer Reviewed Journal) Henning, J.A., Townsend, M.S., Mahaffee, W.F., Kenny, S., Haunold, A. 2004. Registration of newport hop. Crop Science.44:1018-1019.PLANT GROWTH REGULATOR EFFECTS OF FUNGICIDES APPLIED TO HOP FOR CONTROL OF POWDERY MILDEW-(Proceedings) Nelson, M.E., Eastwell, K.C., Ocamb, C.M., Mahaffee, W.F., Kenny, S.T., Grove,G. G.  Plant Growth Regulator Effects Of Fungicides Applied To Hop For Control Of Powdery Mildew.RESPONDING TO AN INTRODUCED PATHOGEN: PODSPHAERA MACULARIS (HOP POWDERY MILDEW) IN THE PACIFIC NORTHWEST-(Peer Reviewed Journal) Mahaffe, W.F., Thomas, C.S., Turechek, W.W., Ocamb, C.M., Nelson, M.E., Fox, A., Gubler, W.D. Responding to an Introduced Pathogen: Podosphaera macularis (Hop Powdery Mildew) in the Pacific Northwest.  Online. Plant Health Progress doi:10.1094/PHP-2003-1113-07-RV.EFFECT OF VARIABLE TEMPERATURE ON THE INFECTION FREQUENCY OF SPHAEROTHECA  MACULARIS ON HUMULUS LUPULUS.-(Peer Reviewed Journal) Mahaffee, W.F., Turechek, W., Ocamb, C. Effect of variable temperature on the infection frequency of Podosphaera macularis on Humulus lupulus. Phytopathology. 2003. v93 p. 1587-1592.ROLE OF BIOFILMS IN BIOCONTROL OF BOTRYTIS CINEREA-(Abstract Only) Press, C.M., Mahaffee, W.F., Roche, M.M., Sechler, T.M., Davis, A.L.  Role Of Biofilms In Biocontrol Of Botrytis Cinerea.MICROSCOPIC EVALUATION OF PHYLLOSPHERE COLONIZATION BY A BIOFILM-FORMING BIOCONTROL AGENT-(Abstract Only) Sechler, T.M., Mahaffee, W.F., Press, C.M., Roche, M.M., Dileone, J., Soeldner, A.H.  Microscopic Evaluation Of Phyllosphere Colonization By A Biofilm-Forming Biocontrol Agent.CHARACTERIZATION OF THE BIOFILM PHENOTYPE OF BURKHOLDERIA SP., FP62 AND ITS ROLE IN BIOCONTROL-(Abstract Only) Roche, M.M., Mahaffee, W.F., Press, C.M., Sechler, T.M., Davis, A.L.  Characterization Of The Biofilm Phenotype OF Burkholderia SP., FP62 And Its Role In Biocontrol.THE IMPACT OF VINE SHELTER USE ON THE DEVELOPMENT OF GRAPE POWDERY MILDEW-(Peer Reviewed Journal)CONTROL OF BOTRYTIS DURING PLANT PROPAGATION-(Proceedings)COMPARATIVE EVALUATION OF ENDOPHYTIC BACTERIA FROM CHINESE AND U.S. COTTON CULTIVARS-(Proceedings)RECENT STUDIES ON THE MICROBIAL ECOLOGY OF BACTERIAL ENDOPHYTES IN PLANTS-(Proceedings)BACTERIAL ENDOPHYTES IN AGRICULTURAL CROPS-(Review Article)BIOCONTROL PROCUCTS FOR PLANT DISEASE CONTROL-(Book / Chapter)BIOLOGICAL CONTROL AGENTS FOR PLANT DISEASES REGISTERED IN OREGON-(Other)COMPARATIVE ANALYSIS OF ANTIBIOTIC RESISTANCE, IMMUNOFLUORESCENT COLONY    STAINING, AND A TRANSGENIC MARKER (BIOLUMINESCENCE) FOR MONITORING THE     ENVIRONMENTAL FATE OF A RHIZOBACTERIUM-(Peer Reviewed Journal)TEMPORAL CHANGES IN THE BACTERIAL COMMUNITIES OF SOIL, RHIZOSPHERE, AND    ENDORIZA ASSOCIATED WITH FIELD GROWN CUCUMBER (CUCUMIS SATIVUS L.)-(Peer Reviewed Journal)BACTERIAL COMMUNITIES OF THE RHIZOSPHERE AND ENDORHIZA ASSOCIATED WITH     FIELD-GROWN CUCUMBER PLANTS INOCULATED WITH A PLANT GROWTH-PROMOTING       RHIZOBACTERIUM OR ITS GENETICALLY MODIFIED DERIVATIVE-(Peer Reviewed Journal)  ARS News ArticlesNo news articles listed for this employee.


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