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United States Department of Agriculture

Agricultural Research Service

Walter F Mahaffee (Walt)
Research Plant Pathologist


Publications (Clicking on the reprint icon Reprint Icon will take you to the publication reprint.)
Early detection of airborne inoculum of Magnaporthe oryzae in turfgrass fields using a quantitative LAMP assay -
Villari, C., Mahaffee, W.F., Mitchell, T.K., Pedley, K.F., Pieck, M.L., Peduto Hand, F. 2016. Early detection of airborne inoculum of Magnaporthe oryzae in turfgrass fields using a quantitative LAMP assay. Plant Disease. doi: 10.1094/PDIS-06-16-0834-RE.
The ebb and flow of airborne pathogens: Monitoring and use in disease management decisions -
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 -
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 -
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 -
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.12421
A scalable plant-resolving radiative transfer model based on optimized GPU ray tracing -
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 -
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 -
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 -
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 -
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 -
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 -
Mahaffee, W.F., Grove, G. 2013. Eutypa canker and dieback. Pacific Northwest Grape IMP Manual.
Powdery mildew -
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 -
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? -
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 -
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 -
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 -
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 -
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 -
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.
Development of 11 polymorphic microsatellite markers for the blackberry rust fungus Phragmidium violaceum -
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.
Permanent Genetic Resources added to Molecular Ecology Resources Database 1 December 2009–31 January 2010 -
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.
Factors Influencing Epidemiology and Management of Blackberry Rust in Cultivated Rubus laciniatus -
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 -
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.
The relationship of biofilm production to biocontrol activity of Burkholderia pyrrocinia FP62 -
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.
Foliar biofilms of Burkholderia pyrrocinia FP62 on geraniums -
Wallace, P., Mahaffee, W.F., Neill, T.M. 2009. Foliar biofilms of Burkholderia pyrrocinia FP62 on geraniums. American Phytopathological Society Abstracts. p. 568.
Forecast and virtual weather driven plant disease risk modeling system -
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 -
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 -
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' -
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.59
Powdery Mildew -
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 -
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.
Gray Mold -
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.
Compendium of Hop Diseases and Pests -
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 -
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 -
Cone Early Maturity -
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.
Injuries Caused by Environmental Factors -
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 -
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.
A Decade of Hop Powdery Mildew in the Pacific Northwest -
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 -
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 -
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 -
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 -
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 -
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 -
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 -
Smith, J.M., Hummer, K.E., Mahaffee, W.F. 2005. Atypical disease response to hop powdery mildew [abstract]. Hortscience. 40(4):1034.
QUANTIFICATION OF AIRBORNE HOP POWDERY MILDEW INOCULUM, A MOLECULAR APPROACH. -
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 -
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.
DETECTION OF PODOSPHAERA CLANDESTINE IN THE AIR OF CHERRY ORCHARDS USING PCR AND SPECIES-SPECIFIC PRIMERS -
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.
RAPID DETECTION AND QUANTIFICATION OF AIRBORNE HOP POWDERY MILDEW INOCULUM -
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 -
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 -
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 -
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 -
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 -
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 -
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 -
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 -
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 -
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. -
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 -
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 -
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 -
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 -
CONTROL OF BOTRYTIS DURING PLANT PROPAGATION -
COMPARATIVE EVALUATION OF ENDOPHYTIC BACTERIA FROM CHINESE AND U.S. COTTON CULTIVARS -
RECENT STUDIES ON THE MICROBIAL ECOLOGY OF BACTERIAL ENDOPHYTES IN PLANTS -
BACTERIAL ENDOPHYTES IN AGRICULTURAL CROPS -
BIOCONTROL PROCUCTS FOR PLANT DISEASE CONTROL -
BIOLOGICAL CONTROL AGENTS FOR PLANT DISEASES REGISTERED IN OREGON -
COMPARATIVE ANALYSIS OF ANTIBIOTIC RESISTANCE, IMMUNOFLUORESCENT COLONY STAINING, AND A TRANSGENIC MARKER (BIOLUMINESCENCE) FOR MONITORING THE ENVIRONMENTAL FATE OF A RHIZOBACTERIUM -
TEMPORAL CHANGES IN THE BACTERIAL COMMUNITIES OF SOIL, RHIZOSPHERE, AND ENDORIZA ASSOCIATED WITH FIELD GROWN CUCUMBER (CUCUMIS SATIVUS L.) -
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 -
Last Modified: 8/26/2016
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