Hanu Pappu

Hanu Pappu

Professor  509-335-3752 Information Technology Building Lab: 123 Vogel Plant Biosciences Building

Research Interests

Viruses and Virus Diseases of Horticultural Crops. Biology and molecular biology of members of the following virus groups: thrips-transmitted tospoviruses (Bunyaviridae), plant pararetroviruses (Caulimoviridae), potyviruses (Potyviridae), and potex and carlaviruses (Flexiviridae). Crops include vegetables, nursery/landscape/ornamentals, and legumes.

Genomics and proteomcis of DNA and RNA viruses pathogenic to horticultural crops. Molecular characterization, gene structure-function relationships (Pappu et al. PNAS 90:36410; virus-host and virus-virus interactions (Mitter et al., 2013. PLoS ONE; Eid et al., 2013. Virus Genes; Bag et al., 2012. PLoS ONE) molecular evolutionary studies using viral genes as markers for attribution (Almeyda et al.,, 2013. Virus Genes; Pappu et al. Arch. Virol. 151: 1015); identification and development of novel promoters from plant pararetroviruses for expression of foreign genes in plants; molecular studies on plant pararetroviruses that exist as integrants in the host plant genome (Pahalawatta et al., Virology 376: 253-257) and use of RNA and DNA viruses of plants as tools for studying virus-host and virus-vector interactions.

Specific areas of research encompass both basic and applied components that include:

  • Molecular and biotechnological approaches for characterization and control of viral diseases of horticultural crops.
  • Genomics, proteomics, molecular epidemiology, conventional and transgenic resistance, virus detection and diagnosis, and host-virus interactions.

Environmental impact assessments, and regulatory framework for transgenic plants/GM crops; impact of plant biotechnology on society; adoption trends of plant biotechnology in the US and other parts of the world.


  • Viruses and Virus Diseases of Plants – PlP511. 4 credits.
    An extensive and intensive overview of the nature of plant viruses including taxonomy, classification, disease induction, economic impact, plant-virus interactions, transmission, genome structure and organization, ecology, epidemiology and control. Cross-listed with University of Idaho (PlSc 511). Offered spring semester of odd years.
  • Molecular Genetics of Plant Pathogen Interactions – PlP 535. 3 credits. Genetic and molecular biological aspects of host-pathogen interactions. Team taught course. Cross-listed with University of Idaho (PlSc 535). Offered spring semester of even years.
  • General Plant Pathology – PlP 429. 3 credits. Classification, symptoms, causes, epidemiology, and control of plant diseases. Team taught (with Dr. Tim Murray). Offered every fall semester.

Outreach Activities

Pappu, H.R, and S.D. Wyatt. Viral Diseases of Dahlia. A web page with information on diagnosis and management of viral diseases of dahlia. Supported by the American Dahlia Society and the WSU Agricultural Research CenterRead the article on dahlias in the May 2008 issue of the Washington State Magazine

Dahlia Resource Centre


  • Grant Review Panel Member: USDA-NIFA, NSF, The US National Academies
  • Academic Editor, PLoS ONE (2013- )
  • Associate Editor, Journal of Plant Pathology (2014- )
  • Secretary, International Working Group on Viruses of Vegetables and Legumes (2011-2014)
  • Administrative Advisor, WERA-20 (Virus and Virus-Like Diseases of Fruit Trees, Small Fruits, and Grapevines)
  • Multistate Research Committee: W-1008. “Biology and Management of Iris yellow spot virus and Thrips in Onions” Secretary (2009); Vice-Chair (2010); and Chair (2011)
  • Associate Editor, Journal of General Plant Pathology (2011-2014)
  • Associate Editor, Plant Disease (2005-2007)
    Advisory Board, WSU Fulbright Academy
  • Member, Executive Committee, WSU Molecular Plant Sciences Program (2011- )
  • Chair, WSU Institutional Biosafety Committee(2007-2012 )
  • Member, WSU Institutional Biosafety Committee (2004-2006)
  • WERA-89 Potato Virus Disease Control- Secretary (2004); Vice-Chair (2005) and Chair (2006)
  • APS Virology Committee (2006- )
  • APS Pathogen Detection and Diagnostics Committee (2005- )
  • Chair, Department of Plant Pathology Social Activities Committee (2005-2008)
  • Graduate Student Recruitment Committee, Department of Plant Pathology (2004-2006)
  • Graduate Student Admissions Committee, Department of Plant Pathology (2005-2008)

Professional Experience

  • Carl F., & James J. Chuey Endowed Chair, September 2017
  • Professor, July 2010-
  • Department Chair, 2008-2013. Administered the state-wide research and extension programs in plant pathology and the plant pathology graduate program (M.S. and Ph.D).
  • Professor and Chair, July 2010-August 2013
  • Associate Professor and Chair, December 2008-June 2010
  • Associate Professor (60% Research, 40% Teaching), October 2002- June 2010
  • Biotechnologist, Biotechnology Regulatory Services, USDA-APHIS, Riverdale, MD, 2001-2002
  • Assistant and Associate Professor, University of Georgia, 1995-2001 (75% Research, 25% Extension)
  • Postdoctoral Associate, University of Florida, Gainesville, FL, 1990-1994 (with Prof. Charles Niblett)


Ongoing projects

  • Thrips and tospoviruses in various vegetable and legume cropping systems
  • Molecular studies on tuber necrosis causing viruses of potato – PVY, Potato mop top virus, and Tobacco rattle virus
  • Vegetable IPM in Sub-Saharan Africa and South Asia: Geminiviruses, Potyviruses, and Tospoviruses
  • Iris yellow spot virus epidemics in onion bulb and seed crops: Epidemiology, biological and molecular analysis of virus isolates, conventional and biotechnological approaches for introducing virus resistance, IPM
  • Maize (corn) lethal necrosis disease in Africa
  • Aphid-transmitted viruses in cool season food legumes: Biology, epidemiology and virus resistance
  • New and emerging viruses affecting nursery and landscape industry
  • Biological and molecular studies of Dahlia mosaic caulimovirus
  • Molecular basis of potato-virus interactions
  • Geminiviruses – molecular characterization and phylogeography

International Research Initiatives and Collaborations

Several ongoing international collaborative projects with scientists in Australia, Azerbaijan, Canada, Chile, Czech Republic, Egypt, France, India, Indonesia, Italy, Kenya, Lithuania, Mauritius, Mexico, the Netherlands, New Zealand, Pakistan, Peru and Turkey on tospoviruses of vegetables and legumes, and viruses of nursery, landscape, and ornamentals.

Awards and Honors

  • Honorary Professor, University of Queensland, Australia (2019)
  • Alexander von Humboldt Research Award (2018)
  • Chuey Endowed Chair (2017)
  • Fellow, American Phytopathological Society (2015)
  • Fellow, National Academy of Agricultural Sciences of India (2016)
  • International Research Fellow, Japan Society for Promotion of Science, Government of Japan (2015)
  • Award of Excellence in Research, College of Agriculture, Human and Natural Resource Sciences (CAHNRS), WSU (2015)
  • Fulbright Distinguished Chair (2015)
  • OECD Fellow, Institute for Virus Research, Torino, Italy (2013)
  • Professor B.P. Pal Distinguished Chair, Indian National Science Academy, New Delhi (2013)
  • WSU CAHNRS Dean’s Meritorious Service Award (2012)
  • WSU CAHNRS Team Interdisciplinary Award (2012)
  • K.C. Mehta and Manoranjan Mitra Award, Indian Phytopathologial Society (2012)
  • US Fulbright Specialist (2011)
  • US Fulbright Scholar, Alexandria University, Alexandria, Egypt (2009)
  • Award of Excellence, Western Association of Agricultural Experiment Station Directors (2008)
  • Mentor of the Year Award Nominee, WSU Women and Leadership Alliance Forum (2007)
  • OECD Fellow, Bulb Research Institute, Lisse, The Netherlands (2006)
  • Advisor of Merit Award by the Graduate and Professional Students Association, WSU (2005)
  • Certificate of Recognition for Inventors from WSU President Lane Rawlins (2004)
  • President Samuel H. Smith Distinguished Professorship (2002)
  • Certificate of Appreciation by the USDA-APHIS (2002)
  • Research and Education Award by the Georgia Peanut Commission (1999)
  • Peanut Research and Education Award by the American Peanut Council (1998)
  • Bailey Award Nominee, American Peanut Research and Education Society (1997)
  • Excellence in Research Award by the University of Georgia, Tifton Campus (1997)
  • Best Research Presentation Award by the Georgia Association of Plant Pathologists (1996)
  • Dr. Myer Horowitz Graduate Scholarship from the University of Alberta (1989)

National and International Leadership Activities

Selected Publications

Review Articles/Book Chapters/Proceedings

  • Gnanasekaran, P., and H.R. Pappu. (2023). Protein-Protein Interactions. Methods in Molecular Biology. Springer. In press
  • Divya, K, Y. Zhai, T. Makeshkumar, E. Moriones, and H. R. Pappu (2023). Genome editing strategies: A way forward for developing resistance against plant viruses. In “Basic, Applied and Strategic Management of Plant Diseases”. Eds. C.D. Mayee, P.K. Chakrabarty, J. Kumar and M.S. Saharan. Springer. In Press
  • Söderlund-Venermom, M., A. Varma, D. Guo, D.P. Gladue, E. Poole, F.H. Pujol, H.R. Pappu, J. Romalde, L. Kramer, M. Baz, M. Venter, M.D. Moore, M.M. Nevels, S. Ezzikouri, V.N. Vakharia, W.C. Wilson, Y. Malik, Z. Shi, and A. Sayed. Abdel-Moneim (2022). World Society for Virology First International Conference: Tackling Global Virus Epidemics. Virology 566: 114–121.
  • Nilon, A., K. Robinson, H.R. Pappu, and N. Mitter (2021). Current status and potential of RNA Interference for the management of Tomato spotted wilt virus and thrips vectors. Pathogens 10(3), 320;
  • Pappu, H.R., A.E. Whitfield, and A. Oliveira (2020). Tomato spotted wilt virus (Tospoviridae). Encyclopedia of Virology. 4th edition. Elsevier Press. Reference Module in Life Sciences
  • Resende, R., A.E. Whitfield, and H.R. Pappu (2020). Orthotospoviruses (Tospoviridae). Encyclopedia of Virology. 4th edition. Elsevier Press. Reference Module in Life Sciences.
  • Worrall, E.A., A. Hamid, K.T. Mody, N. Mitter, and Hanu R. Pappu (2018). Nanotechnology for plant disease management. Agronomy 8, 285; doi:10.3390/agronomy8120285
  • Ramesh, S.V., P. Sahu, Manoj Prasad, S. Praveen and H.R. Pappu (2017). Geminiviruses and plant hosts: A closer examination of the molecular arms race. Viruses 9:256. doi:10.3390/v9090256
  • Pappu, H.R. (2015). Thrips-transmitted Iris yellow spot virus – A threat to onion sustainability. Agricultural Research Journal 52: 10-12
  • Pappu HR, Bag S (2014). ICTV taxonomic proposal 2014.004aV.A.v2. Tospovirus_sp. Create 1 new species in the genus Tospovirus, family Bunyaviridae. Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2015). Archives of Virology 160:1837–1850. (pdf)
  • Jain, R.K., B. Mandal, H R Pappu and S.K. Holkar (2014). Watermelon bud necrosis virus: A new species in the genus Tospovirus isolated from Citrullus lanatus and other cucurbitaceous hosts. International Committee for Taxonomy of Viruses. In press.
  • Pappu, H.R. (2013). Viruses. In: Onion Health Management & Production. Onion IPMpipe. Edited by Howard Schwartz. 98pp. Colorado State University, Ft. Collins, CO.
  • Mandal, B., R. K. Jain, M. Krishnareddy, N.K. Krishna Kumar, K.S. Ravi, and H. R. Pappu (2012). Emerging Problems of Tospoviruses (Bunyaviridae) and their Management in the Indian Subcontinent. Plant Disease 96:468-479.
  • Makkouk, K., H.R. Pappu and S.G. Kumari (2012). Virus Diseases of Peas, Beans and Faba Bean in the Mediterranean Region. Advances in Virus Research 84:367-402.
  • Chastagner, G., G. Hanks, M. Daughtrey, I. Yedidia, T. Miller, and H. Pappu (2012). Sustainable Production and Integrated Management: Environmental Issues. Pp. 363-420. In: Kamenetsky, R., and H. Okubo (Eds), Ornamental Geophytes: From Basic Science to Sustainable Horticultural Production. Taylor and Francis. 553 pp.
  • Pappu, H.R., R.A.C. Jones, and R.K. Jain (2009). Global status of tospovirus epidemics in diverse cropping systems: Successes gained and challenges that lie ahead. Virus Research 141:219–236.
  • Pappu, H.R. (2008). Tomato spotted wilt virus (pdf) (Bunyaviridae). In: Encyclopedia of Virology. 3rd edition. Brian Mahy and Marc van Regenmortel (Eds.). Elsevier Ltd, Oxford, UK. pp. 133-138.
  • Gent, D., L.J. du Toit, S.F. Fichtner, S. Krishna Mohan, H.R. Pappu, and H.F. Schwartz. 2006. Iris yellow spot virus: An emerging threat to onion bulb and seed production (pdf)Plant Disease 90:1468-1480.
  • Munyaneza, J.E, J.M. Crosslin, A.S. Jensen, P.B. Hamm, P.E. Thomas, H.R. Pappu and A. Schreiber. 2005. Update on the potato purple top disease in the Columbia Basin (pdf). In: Proceedings, 44th Annual Washington State Potato Conference, 1-3 February 2005, Moses Lake, WA. pp. 57-70.
  • du Toit, L. J., Pelter, G. Q., and Pappu, H. R. 2004. IYSV challenges to the onion seed industry in Washington (pdf). Pages 103, 213-217 in: Proc. National Allium Res. Conf., Grand Junction, CO. Colorado State University, Fort Collins, CO.
  • Bertrand, P.F., and H.R. Pappu. 2001. Pecan bunch. In: Compendium of Nut Tree Diseases. American Phytopathological Society Press, St. Paul, MN.
  • Culbreath, A.K., J. W. Todd, S.L. Brown, J.A. Baldwin, and H. R. Pappu. 1999. A genetic and cultural package for management of Tomato spotted wilt virus in peanut. Biological and Cultural Tests 14:1-8.
  • Pappu, H.R. 1999. Biosafety issues of virus-resistant transgenic plants. pp 51-64. In: Biotechnology, Biosafety and Biodiversity: Scientific and Ethical Issues for Sustainable Development. S. Shantharam and J.F. Montgomery (Eds.). Science Publishers, Inc. Keene, NH.
  • Pappu, H.R. and C.L. Niblett. 1995. Application of recombinant DNA technology in plant protection: Molecular approaches to engineering virus resistance in crop plants. World Journal of Microbiology and Biotechnology 11:426-437.

Refereed Journal Articles

  • Manasseh, R., A. Berim, M. Kappagantu, L. Moyo, D. Gang, and H.R. Pappu (2023). Pathogen-triggered metabolic adjustments to potato virus Y infection in potato. Frontiers in Plant Science. In Press.
  • Iftikhar, R., A. Ghosh, and H.R. Pappu (2023). Mitochondrial genetic diversity of Thrips tabaci (Thysanoptera: Thripidae) in onion growing regions of the USA. Journal of Economic Entomology. In Press.
  • Zhai, Y., A. Roy, H. Peng, D.L. Mullendore, G. Kaur, B. Mandal, S.K. Mukherjee and H.R. Pappu (2022). Identification and functional analysis of four RNA silencing suppressors in begomovirus croton yellow vein mosaic virus. Frontiers in Plant Science.
  • Fletcher, S., J.R. Peters, C.A. Olaya-Arias, D.M. Persley, R.G. Dietzgen, B.J. Carroll, H.R. Pappu, and N. Mitter (2022). Tospoviruses induce small interfering RNAs targeting viral sequences and endogenous transcripts in solanaceous plants. Pathogens
    11, 745.
  • Zhai, Y., B. Davenport, K. Schuetz, and H.R. Pappu (2022). An on-site test for rapid and sensitive detection of Potato mop-top virus in potato leaves and tubers. PLoS One.
  • Jewell, J.B., A. Berim, D. Tripathi, C. Gleason, C. Olaya, H.R. Pappu, D.R. Gang, and K. Tanaka (2022). Activation of indolic glucosinolate pathway by extracellular ATP in Arabidopsis. Plant Physiology. In Press.
  • Gupta, N., K.K. Reddy, P. Gnanasekaran, Y. Zhai, H.R. Pappu, and S. Chakraborty. (2022). Functional aspects of a new ORF βV1 encoded by radish leaf curl betasatellite. Frontiers in Plant Science. In Press.
  • Fu, M., H.R. Pappu, G. Vandemark, and W. Chen (2022). Genome sequence of Sclerotinia sclerotiorum hypovirulence-associated DNA Virus-1 found in the fungus Penicillium olsonii isolated from Washington State, USA. Genome Resource Announcements 11(4):e0001922. doi: 10.1128/mra.00019-22
  • Zhai, Y., P. Gnanasekaran, and H.R. Pappu (2021). Identification and characterization of targets of Tomato spotted wilt tospovirus silencing suppressor in Nicotiana benthamiana. Pathogens 10(1), 27;
  • Moyo, L., G. Raikhy, A. Hamid, I. Mallik, N.C. Gudmestad, S.M. Gray and H.R. Pappu (2021). Phylogenetics of tobacco rattle virus isolates from potato (Solanum tuberosum L.) in the USA: A multi-gene approach to evolutionary lineage. Virus Genes.
  • Zhai, Y., A. Roy, H. Peng, D.L. Mullendore, G. Kaur, B. Mandal, S.K. Mukherjee and H.R. Pappu (2021). Identification and functional analysis of four RNA silencing suppressors in begomovirus croton yellow vein mosaic virus. Frontiers in Plant Science. In press.
  • Konakalla, N.C., A. Deraniyagala, A.K. Culbreath, H.R. Pappu, and S. Bag. (2021). Induction of plant resistance in tobacco (Nicotiana tabacum) against Tomato spotted wilt orthotospovirus through foliar application of dsRNA. Viruses 13, 662.
  • Tabassum, A., S.V. Ramesh, Y. Zhai, R. Iftikhar, C. Olaya, and H.R. Pappu (2021). Viruses without Borders: Global analysis of the population structure, haplotype distribution, and evolutionary pattern of Iris yellow spot virus. Frontiers in Microbiology.
  • Ramesh, S.V., S. Yogindran, G. Prabu, S. Chakraborty, S. Winter, and H.R. Pappu. (2021). Virus and viroid-derived small RNAs as modulators of host gene expression: Molecular insights into pathogenesis. Frontiers in Microbiology.
  • Zhai,Y., H. Peng, M.M. Neff, and H.R. Pappu (2020). Emerging molecular links between plant photomorphogenesis and virus resistance. Frontiers in Plant Science.
  • Olaya, C., S. Fletcher, Y. Zhai, J. Peters, P. Margaria, S. Winter, N. Mitter, and H.R. Pappu (2020). The Tomato spotted wilt virus (TSWV) genome is differentially targeted in TSWV-Infected tomato (Solanum lycopersicum) with or without Sw-5 Gene. Viruses 12, 363; doi:10.3390/v12040363
  • Davenport, B., D. Groth-Helms, R. Li, S. Zhang, S.M. Gray, J. Ingram, and H.R. Pappu (2020). Development of a real-time duplex isothermal assay for the detection of Tobacco rattle virus and an endogenous internal RNA control in ornamental hosts. Acta Horticulturae 1288: 245-255. DOI: 10.17660/ActaHortic.2020.1288.37
  • Manglli, A., L. Tomassoli, A. Tiberini, G.E. Agosteo, A. Fontana, H.R. Pappu, and G. Albanese (2020). A survey on the infection of Onion yellow dwarf virus and Iris yellow spot tospovirus in seed and bulb productions systems of onion in Calabria, Italy. European J. Plant Pathology 156: 767–778.
  • Zhai, Y. I. Mallik, A. Hamid, A. Tabassum, N. Gudmestad, S. M. Gray, and H. R. Pappu. (2020). Genetic diversity in Potato mop-top virus populations in the United States and a global analysis of the PMTV genome. Eur. J. Plant Path DOI 10.1007/s10658-019-01836-6
  • Iftikhar, R., L. Moyo, and H.R. Pappu. (2020). A loop-mediated isothermal amplification (LAMP) assay for the detection of dahlia mosaic caulimovirus in dahlia (Dahlia variabilis). Annals of Applied Biology 176:203–209. DOI: 10.1111/aab.12574
  • Chakrabarty, P., P. Kumar, B. B. Kalbande, R. L. Chavhan, V. Koundal, D. Monga, H. R. Pappu, A. Roy, and B. Mandal (2020). Recombinant variants of cotton leaf curl Multan virus is associated with the breakdown of leaf curl resistance in cotton in northwestern India. Virus Disease.
  • Zhai, Y., H. Peng, M.M. Neff, and H.R. Pappu (2019). Putative auxin and light responsive promoter elements from the Tomato spotted wilt tospovirus genome, when expressed as cDNA, are functional in Arabidopsis. Frontiers in Plant Science.
  • Roy, A., Y. Zhai, J. Ortiz, M.M. Neff, B. Mandal, S.K. Mukherjee and H.R. Pappu (2019). Multiplexed editing of a begomovirus genome restricts escape mutant formation and disease development. PLoS One.
  • Olaya, C., B. Adhikari, G. Raikhy, J. Cheng, and H.R. Pappu (2019). Identification and localization of Tospoviridae family-wide conserved residues in 3D models of the nucleocapsid and the silencing suppressor proteins. Virology Journal 16:7
  • Kamal, H., F. Minhas, D. Tripathi, W.A. Abbasi, M. Hamza, R. Mustafa, M.Z. Khan, S. Mansoor, H.R. Pappu and I. Amin (2019). βC1, pathogenicity determinant encoded by Cotton leaf curl Multan betasatellite, interacts with calmodulin-like protein 11 in Gossypium hirsutum. PLoS ONE.
  • Yin, C., S.R. Ramachandran, Y. Zhai, C. Bu, H.R. Pappu and S.H. Hulbert (2019). A novel fungal effector from Puccinia graminissuppressing RNA silencing and plant defense responses. New Phytologist doi: 10.1111/nph.15676
  • Hamid, A, Y. Zhai; S.V. Ramesh, and H.R. Pappu (2019).  Complete genome characterization and population dynamics of Potato virus Y-NTN strain from India. Virus Disease
  • Kamal, H, M. Fayyaz-ul-Amir Afsar, F. Muhammad, D. Tripathi, H. Muhammad, R. Mustafa, Z.M. Khan, S. Mansoor, H.R. Pappu, and I. Amin. (2019). In silico prediction and validations of domains involved in Gossypium hirsutum SnRK1 protein interaction with Cotton leaf curl Multan virus betasatellite-encoded βC1. Frontiers in Plant Science. DOI=10.3389/fpls.2019.00656
  • Paudel, S., E.J. Bechinski, H.R. Pappu, B. Stokes, and S.D. Eigenbrode (2018). Deriving Economic Models for Pea Aphid, Acyrthosiphon pisum (Harris), as a Direct-Pest and a Virus-Vector on Commercial Lentils. J Econ Entomol. DOI:10.1093/jee/toy188
  • Wang, J., Y. Zhai, D. Zhu, W. Liu, H.R. Pappu, and Q. Liu (2018). Whole-genome characterization of Prunus necrotic ringspot virus (PNRSV) infecting sweet cherry in China. Genome Announcements. DOI: 10.1128/genomeA.00060-18
  • Vaira, A.M., L. Miozzi, M. Vallino, A. Carra, R. Lenzi, D. Salvi, J. Hammond and H.R. Pappu (2018). Evidence of new viruses infecting freesia hybrids showing necrotic disease.    Acta Horticulturae 1193: 21-28. Proc. XIV Int. Symp. on Virus Diseases of Ornamental Plants. Eds.: J. Hammond et al.
  • Senthilraja, C., Renukadevi, P., Malathi, V.G., Nakkeeran, S and Pappu, H.R. (2018). Occurrence of tomato spotted wilt virus infecting snapdragon (Antirrhinum majus) in India. Plant Disease102:1676.
  • Krupovic, M., J. Blomberg, J.M. Coffin, I. Dasgupta, H. Fan5, A.D. Geering, R. Gifford, B. Harrach, R. Hull, W. Johnson, J.F. Kreuze, D. Lindemann, C. Llorens, B. Lockhart, J. Mayer, E. Muller, N. Olszewski, H.R. Pappu, M. Pooggin, K. Richert-Pöggeler, S. Sabanadzovic, H. Sanfaçon, J.E. Schoelz, S. Seal, L. Stavolone, J.P. Stoye, P. Teycheney, M. Tristem, E.V. Koonin, and J.H. Kuhn (2018). Ortervirales: A new viral order unifying five families of reverse-transcribing viruses. Journal of Virology 92:e00515-18.
  • Ramesh, S.V., S. Williams, N. Mitter and H.R. Pappu (2017). Transcriptome-wide Identification of host genes targeted by Tomato spotted wilt virus (TSWV)-derived small interfering RNAs in TSWV-resistant and susceptible tomato cultivars. Virus Research 238:13–23.
  • Olaya, C., N. Velásquez, M. Betancourt, W. J. Cuellar, and H.R. Pappu (2017). First Report of natural infection of tomato (Solanum lycopersicum L.) and bell pepper (Capsicum annuum) by Alstroemeria necrotic streak virus in Colombia. Plant Disease 101:1065.
  • Moyo, L., S.V. Ramesh, M. Kappagantu, S. Sathuvalli, N. Mitter, and H.R. Pappu (2017). Analysis of the effect of three biologically distinct strains of Potato virus Y at the potato transcriptome level. Virology Journal 14:129. DOI 10.1186/s12985-017-0803-8
  • Srinivasan, R., M. Abney, A. Culbreath, R. Kemerait, S. Tubbs, S.Monfort, and H.R. Pappu (2017). Three decades of managing Tomato spotted wilt virus in peanut in southeastern United States. Virus Research. 241:203-212.
  • Mitter, N., Y. Zhai, A.X. Bai, K. Chua, S. Eid, M. Constantin,  R. Mitchell, and H.R. Pappu (2016). Evaluation and Identification of candidate genes for artificial microRNA-mediated resistance to Tomato spotted wilt virus(Tospovirus: Bunyavirdae). Virus Research 211:151-158.
  • Tabassum, A., S. Reitz, P. Rogers, and H.R. Pappu (2016). First Report of Iris yellow spot virus infecting green onion (Allium fistulosum) in the USA. Plant Disease.
  • Fletcher, S.J., A. Shrestha, J. Peters, B.J. Carroll, R. Srinivasan, H.R. Pappu, and N. Mitter (2016). The Tomato spotted wilt virus genome is processed differentially in its plant host Arachis hypogaea and its thrips vector Frankliniella fusca. Frontiers in Plant Science. doi: 10.3389/fpls.2016.01349
  • Margaria, P., L. Miozzi, C. Rosa, M.J. Axtell, M. Ciuffo, H.R. Pappu, M. Turina (2016). Comparison of small RNA profiles in Nicotiana benthamiana and Solanum lycopersicum infected by Polygonum ringspot tospovirus reveals host-specific responses to viral infection Virus Research 211:38–45
  • Karavina, C., J. Ibaba, A. Gubba and H.R. Pappu (2016). First report of Iris yellow spot virus infecting garlic and leek in Zimbabwe. Plant Disease 100:657.
  • Ramesh, S.V., and H.R. Pappu (2016). Sequence Characterization, molecular phylogeny reconstruction and recombination analysis of the Large RNA of Tomato spotted wilt virus (Tospovirus: Bunyaviridae) from the United States. BMC Research Notes 9:200.DOI 10.1186/s13104-016-1999-1
  • Wang, J., Y. Zhai, W. Liu, A. Dhingra, H.R. Pappu, and Q. Liu (2016). Structure and genome organization of Cherry virus A (Capillovirus, Betaflexiviridae) from China using small RNA sequencing. Genome Announcements. Published online 2016 May 12. doi:  10.1128/genomeA.00364-16
  • Velásquez-Valle, R., L. R. Reveles-Torres, S. Salas-Muñoz, J. A. Mauricio-Castillo, and H.R. Pappu. (2016). First confirmed report of Iris yellow spot virus in onion nurseries in Zacatecas, Mexico. Plant Disease DOI10.1094/PDIS-01-16-0061-PDN
  • Wang, J., Y. Zhai, W. Liu, D. Zhu, H.R. Pappu, and Q. Liu (2016). The complete genomic characterization of plum bark necrosis stem pitting-associated virus(PBNSPaV) infecting sweet cherry in China. Genome Announcements. 2016 May 19;4(3). pii: e00413-16. doi: 10.1128/genomeA.00413-16.
  • Tripathi, D., G. Raikhy, and H.R. Pappu (2015). Movement and nucleocapsid proteins coded by two tospovirus species interact through multiple binding regions in mixed infections. Virology 478:143-53. doi: 10.1016/j.virol.2015.01.009
  • Tripathi, D., G. Raikhy, R. Dietzgen, M. Goodin, and H.R. Pappu (2015). In vivo Localization of Iris yellow spot virus (Bunyaviridae: Tospovirus)-encoded Proteins and Identification of Interacting Regions of Nucleocapsid and Movement Proteins.  PLoS ONE 10(3): e0118973. doi:10.1371/journal.pone.0118973
  • Tripathi, D., and H.R. Pappu (2015). Evaluation of Acibenzolar-S-Methyl-Induced Resistance against Iris yellow spot tospovirus. European J. Plant Pathology 142:855–864. DOI 10.1007/s10658-015-0657-0
  • Margaria, P.,  L. Miozzi, C. Rosa, M.J. Axtell, H.R. Pappu, M. Turina (2015). Small RNA profiles of wild-type and silencing suppressor-deficient tomato spotted wilt virus-infected Nicotiana benthamiana. Virus Research. DOI: 10.1016/j.virusres.2015.05.021.
  • Almeyda, C.V., G. Raikhy, H.R. Pappu (2015). Characterization and comparative analysis of promoter elements from three plant  pararetroviruses associated with Dahlia (Dahlia variabilis). Virus Genes 51:96-104. DOI 10.1007/s11262-015-1196-7
  • Bag, S., H.F. Schwartz, C.S. Cramer, M.J. Havey, and H.R. Pappu (2015). Iris yellow spot virus (Tospovirus: Bunyaviridae): From obscurity to research priority. Molecular Plant Pathology 16(3), 224–237. DOI:10.1111/mpp.12177
  • Mustafa T, Horton DR, Cooper WR, Swisher KD, Zack RS, Pappu HR, et al. (2015). Use of electrical penetration graph technology to examine transmission of ‘Candidatus Liberibacter solanacearum’ to potato by three haplotypes of
    potato psyllid (Bactericera cockerelli; Hemiptera:Triozidae). PLoS ONE 10(9): e0138946. doi:10.1371/journal.pone.0138946
  • Renukadevi, P., K. Nagendran, S. Nakkeeran, G. Karthikeyan, M. Jawaharlal, D. Alice, V.G. Malathi and H.R. Pappu (2015). First report of natural occurrence of Tomato spotted wilt virus in India. Plant Disease 99:1190. DOI 10.1094/PDIS-01-15-0126-PDN
  • Mahuku, G., B.E. Lockhart, B. Wanjala, M.W. Jones, J.N. Kimunye, L,R. Stewart, B.J. Cassone, S. Sevgan, J. Nayasani, E. Kusia, P. Lava Kumar, C.L. Niblett, A. Wangai, A. Kiggundu, G. Asea, H.R. Pappu, B.M. Prasanna, and M.G. Redinbaugh (2015). Maize lethal necrosis (MLN), an emerging threat to maize-based food security in sub-Saharan Africa. Phytopathology 105:956-965.
  • Kusia, E.S., S. Subramanian, J.O Nyasani, F. Khamis, J. Villinger, E.M. Ateka, H.R. Pappu (2015). First report of lethal necrosis disease associated with co-infection of finger millet with Maize chlorotic mottle virus and Sugarcane mosaic virus in Kenya. Plant Disease 99:899.
  • Iftikhar, R., S.V. Ramesh, S. Bag, M. Ashfaq and H.R. Pappu. 2014. Global analysis of population structure, spatial and temporal dynamics of genetic diversity and evolutionary lineages of Iris yellow spot virus (Tospovirus: Bunyaviridae). Gene 547:111-118. DOI: 10.1016/j.gene.2014.06.036
  • Margaria, P., L. Miozzi, M. Ciuffo, H.R. Pappu, and M. Turina 2014. Whole genome sequences of two distinct European Tomato spotted wilt virus (Tospovirus:Bunyaviridae) isolates. Archives of Virology DOI 10.1007/s00705-014-2256-3
  • Cramer, C., N. Singh, N. Kamal, and H.R. Pappu 2014. Screening onion plant introduction accessions for tolerance to onion thrips and Iris yellow spot virus. HortScience 49:1253-1261.
  • Schwartz, H.F., Diane Alston, Jeff Alwang, Michael Bartolo, Tamla Blunt, Charles O. Boateng, Bonnie Bunn, Chris S. Cramer, Whitney Cranshaw, Jeff Davidson, Mike Derie, Jeff Doran, Keith Douce, Dan Drost, Lindsey J. du Toit, J. Gao, Thaddeus Gourd, Beth Gugino, Bob Hammon, Janet Hardin, Mary Hausbeck, George Jibilian, Jed Lafferty, Joseph LaForest, Mark S. McMillan, S. Krishna Mohan, Jarrod Morrice, Brian A. Nault, Claudia Nischwitz, George Norton, Kristen Otto, Hanu R. Pappu, Mike Petersen, Ram Sampangi, Brenda Schroeder, Will Secor, Stephanie Szostek, Ned Tisserat, Mark E. Uchanski, Jim VanKirk, Tim Waters, Prissana Wiriyajitsomboon, and Carrie Wohleb. 2014. Onion ipmPIPE: A Coordinated Effort to Improve the Management of Onion Thrips and Iris yellow spot virus for the U.S. Onion Industry. Plant Health Progress doi: 10.1094/PHP-FE-14-0026
  • Zhai, Y., S. Bag, N. Mitter, M. Turina, and H.R. Pappu. 2014. Mutational analysis of two highly conserved motifs in the silencing suppressor coded by tospoviruses (Tospovirus, Bunyaviridae). Archives of Virology. 159:1499-1504. DOI 10.1007/s00705-013-1928-8
  • Zhai, Y., R. Miglino, R. Sorrentino, V. Masenga, D. Alioto, and H.R. Pappu. 2014. Complete genomic characterization of Eggplant mottled dwarf virus (Rhabdovirus:Rhabdoviridae) from Agapanthus spp by deep sequencing and de novo assembly. J. Plant Pathology doi: 10.4454/JPP.V96I3.003
  • Bag, S., S. Rondon, K.L. Druffel, D.G. Rileyand H.R. Pappu. 2014. Seasonal dynamics of thrips (Thrips tabci) transmitters of Iris yellow spot virus (Tospovirus:Bunyaviridae), a serious viral pathogen of onion bulb and seed crops. Journal of Economic Entomology 107: 75-82. DOI:
  • Margaria, P., L. Miozzi, M. Ciuffo, H.R. Pappu, and M. Turina. 2014. Complete genome sequence of Polygonum ringspot virus (Tospovirus:Bunyaviridae). Archives of Virology 159:3149–3152. DOI 10.1007/s00705-014-2166-4
  • Lin, Y-H, J. Abad, C. J. Maroon-Lango, K.L. Perry, and H.R. Pappu. 2014. Molecular characterization of domestic and exotic Potato virus S isolates and a global analysis of genomic sequences. Archives of Virology 159:2115–2122. DOI 10.1007/s00705-014-2022-6
  • Lin, Y-H., D. A. Johnson, and H.R. Pappu. 2014. Effect of Potato virus Sinfection on late blight (Phytophtora infestans) in potato (Solanum tuberosum). Amer. J. of Potato Research. DOI 10.1007/s12230-014-9394-8.
  • Naveed, K., N. Mitter, A. Dhingra, and H.R. Pappu. 2014. Comparative Analysis of virus-specific small RNA profiles of three biologically distinct strains of Potato virus Y (PVY) in PVY-infected potato (Solanum tuberosum) cv. Russet Burbank. Virus Research 191:153–160.
  • Ramesh, S.V., G. Raikhy, C.R. Brown, J.L. Whitworth, and H.R. Pappu. 2014. Complete genomic characterization of Potato mop top virus from the United States. Archives of Virology DOI 10.1007/s00705-014-2214-0
  • Sundaraj, S., R. Srinivasan, A.K. Culbreath, D.G. Riley, and H.R. Pappu. 2014. Host plant resistance against Tomato spotted wilt virus (Tospovirus:Bunyaviridae) in peanut (Arachis hypogaea) and its impact on virus transmission, virus population genetics, and vector feeding behavior and survival. Phytopathology 104:202-210.
  • Almeyda, C.V., S.G. Eid, D. Saar, M. Samuitiene, and H.R. Pappu. 2014. Genetic diversity among endogenous plant pararetroviral sequences from geographically diverse sources of dahlia (Dahlia spp.). Virus Genes 48: 140-152. DOI 10.1007/s11262-013-0997-9
  • Eid, S., and H.R. Pappu. 2014. Expression of endogenous para-retroviral genes and molecular analysis of the integration events in its plant host Dahlia variabilisVirus Genes 48:153-159. DOI 10.1007/s11262-013-0998-8
  • Eid, S., and H.R. Pappu. 2014. Biological studies of three caulimoviruses associated with dahlia (Dahlia variabilis). Canadian Journal of Plant Pathology. DOI: 10.1080/07060661.2013.871753
  • Vemulapati, B., K.L. Druffel, D. Husebye, S.D. Eigenbrode and H.R. Pappu. 2014. Development and application of ELISA assays for the detection of two members of the family Luteoviridae: Pea enation mosaic virus (genus Enamovirus) and Bean leafroll virus (genus Luteovirus). Annals of Applied Biology 165:130-136.
  • Zhai, Y., R. Miglino, R. Sorrentino, V. Masenga, D. Alioto, and H.R. Pappu. 2014. First Report of Eggplant mottled dwarf virus infection of Agapanthus sp. in Italy. New Disease Reports 29:20.
  • Mitter, N., V. Koundal, S. Williams, and H.R. Pappu. 2013. Differential expression of virus-specific small RNAs in Tomato spotted wilt virus(Tospovirus:Bunyaviridae)-infected experimental and commercial hosts. PLoS ONE 8(10): e76276. doi:10.1371/journal.pone.0076276
  • Kalischuk, M., B. Müller, A. Fusaro, D. Prüfer, P.M. Waterhouse, H.R. Pappu, and L.M. Kawchuk. 2013. Complete genomic sequence of a Rubus yellow net virus isolate and detection of genome-wide pararetrovirus-derived small RNAs. Virus Research 178:306–313.
  • Sengoda, V.G., J.L. Buchman, D.C. Henne, H.R. Pappu, and J.E. Munyaneza. 2013.“Candidatus Liberibacter solanacearum” titer over time in the potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae), following acquisition from infected potato and tomato plants. Journal of Economic Entomology106:1964-1972.
  • Pappu, H.R., and A. Rauf. 2013. First report of Iris yellow spot virus (Tospovirus:Bunyaviridae) in Indonesia. Plant Disease 97:1665.
  • Birithia, R., S. Subramanian, H. R. Pappu, J. Muthomi and R. D. Narla. 2013. Analysis of Iris yellow spot virus (IYSV, genus Tospovirus) replication in vector and non-vector thrips species. Plant Pathology DOI: 10.1111/ppa.12057
  • Iftikhar, R., S. Bag, M. Ashfaq and H.R. Pappu. 2013. Occurrence of Iris yellow spot virus infecting onion in Pakistan. Plant Disease 97:1517.
  • Bag, S., N. Mitter, S. Eid., and H.R. Pappu. 2012. Genetic complementation between two tospoviruses facilitates the systemic movement of a plant virus silencing suppressor in an otherwise restrictive host. PLoS ONE
  • Media release: Sorensen, E. Viral alliances overcome plant defenses, WSU research finds. WSU Today
  • Bag, S., H.F. Schwartz, and H.R. Pappu. 2012. Characterization of biologically distinct isolates of Iris yellow spot virus (genus Tospovirus, Family Bunyaviridae), a serious pathogen of onion. European Journal of Plant Pathology 134:97-104. DOI 10.1007/s10658-012-0026-1
  • Naveed, K., and H. R. Pappu, 2012. Susceptibility of Arabidopsis ecotypes to infection by Iris yellow spot virus (Genus Tospovirus, family Bunyaviridae). Plant Health Progress. doi:10.1094/PHP-2012-0714-01-RS. Published on-line 14 July 2012.
  • Birithia, R., S. Subramanian, J. Villinger, J. W. Muthomi, R. D. Narla, and H.R. Pappu. 2012. First Report of Tomato yellow ring virus (Tospovirus, Bunyaviridae) Infecting Tomato in Kenya. Plant Disease 96:1384.
  • Lobin, K., H. R. Pappu, and S. P. Benimadhu. 2012. Occurrence and distribution of Iris yellow spot virus (Genus Tospovirus, Family Bunyaviridae) on onion (Allium cepa) in Mauritius. Plant Health Progress. doi:10.1094/PHP-
  • 2012-0826-01-BR. Published on-line August 26, 2012.
  • Mandal, B., R. K. Jain, M. Krishnareddy, N.K. Krishna Kumar, K.S. Ravi, and H. R. Pappu. 2012. Emerging problems of tospoviruses (Bunyaviridae) and their management in the Indian subcontinent. Plant Disease 96:468-479.
  • Srinivasan, R., S. Sundaraj, H.R. Pappu, S. Diffie, D.G. Riley, and R.D Gitaitis. 2012. Transmission of Iris yellow spot virus by Frankliniella fusca and Thrips tabaci (Thysanoptera: Thripidae). Journal of Economic Entomology 105:40-47.
  • Srinivasan, R., S. Diffie, S. Sundaraj, S. Mullis, D.G. Riley, R.D. Gitaitis, and H. R. Pappu. 2011. Evaluation of lisianthus (Eustoma grandiflorum) as an indicator host for Iris yellow spot virus. Plant Disease 95:1520-1527.
  • Eid, S., C. V. Almeyda, D.E. Saar, K.L. Druffel, and H.R. Pappu. 2011. Genomic characterization of para-retroviral sequences in wild Dahlia spp. in natural habitats. Archives of Virology 156:2079–2084. DOI 10.1007/s00705-011-1076-y
  • Vemulapati, B., K.L. Druffel, S.D. Eigenbrode, A. Karasev and H.R. Pappu.2011. Genomic characterization of Pea enation mosaic virus-2 from the Pacific Northwestern USA. Archives of Virology 156: 1897-1900.
  • DOI 10.1007/s00705-011-1074-0
  • Miglino, R., K. L. Druffel, A. R. van Schadewijk, H. R. Pappu. 2011. Molecular characterization of “Allium virus X”, a new potexvirus in the family Flexiviridae, infecting ornamental allium. Archives of Virology 156:2113–2115.
  • DOI 10.1007/s00705-011-1109-6
  • Cramer, C.S., S. Bag, H.F. Schwartz, and H.R. Pappu. 2011. Susceptibility of onion (Allium spp) relatives to Iris yellow spot virus. Plant Disease 95:1319.
  • DOI: 10.1094/PDIS-11-10-0819
  • Eid, S., D.E. Saar, K.L. Druffel, and H.R. Pappu. 2011. Plant para-retroviral sequences in wild Dahlia species in their natural habitats in Mexican mountain ranges. Plant Pathology 60, 378–383. DOI: 10.1111/j.1365-3059.2010.02367.x
  • Lobin, K., A. Saison; B. Hostachy, S.P. Benimadhu, and H.R. Pappu. 2010. First report of Iris yellow spot virus in onion in Mauritius. Plant Disease 94: 1373. DOI: 10.1094/PDIS-10-09-0645.
  • Vemulapati B, K.L. Druffel, S. Eigenbrode, A. Karasev and H.R. Pappu. 2010. Molecular characterization of Pea enation mosaic virus (genus Enamovirus) and Bean leaf roll virus (genus Luteovirus) from the Pacific Northwestern USA. Archives of Virology 155:1713-1715. DOI: 10.1007/s00705-010-0767-0
  • Sether, D.M., W.B. Borth, R.S. Shimabuku, H.R. Pappu, M.J. Melzer, and J.S. Hu. 2010. First report of Iris yellow spot virus in onion in Hawaii. Plant Disease 94:1508. DOI: 10.1094/PDIS-07-10-0531
  • Abdel-Salam, sA.M., M. Al Khazindar, S.G. Eid, and H.R. Pappu. 2010. Identification and characterization of caulimoviral sequences in Dahlia variabilis in Egypt. African J Biotechnology 9: 6835-6839.
  • Miglino, R., K. L. Druffel, and H. R. Pappu. 2010. Identification and molecular characterization of a new potyvirus infecting Triteleia species. Archives of Virology 155:441–443.
  • Lobin, K., K.L. Druffel, H. R. Pappu, and S.P. Benimadhu. 2010. First report of Tomato yellow leaf curl virus (Family Geminiviridae) in tomato in Mauritius. Plant Disease 94: 1261.
  • Bag, S., K.L. Druffel and H.R. Pappu. 2010. Structure and genome organization of the large RNA of Iris yellow spot virus (genus Tospovirus, family Bunyaviridae). Archives of Virology 155:275–279 (DOI 10.1007/s00705-009-0568-5).
  • Sengoda, V.S., J.E. Munyaneza, J.M. Crosslin, J.L. Buchman, and H.R. Pappu. 2010. Phenotypic and etiological differences between psyllid yellows and zebra chip diseases of potato. American Journal of Potato Research 87:41–49 (DOI 10.1007/s12230-009-9115-x).
  • Eid, S., K.L. Druffel, D. Saar, and H.R. Pappu, 2009. Incidence of multiple and distinct species of caulimoviruses in dahlia (Dahlia variabilis). HortScience44:1498–1500.
  • Murray, T.D., H.R. Pappu, and R.W. Smiley. 2009. First report of Soilborne wheat mosaic virus on Triticum aestivum in Washington State. Plant Health Progress. doi:10.1094/PHP-2009-1204-01-BR.
  • Lin, Y-H., K.L. Druffel, J. Whitworth, M.J. Pavek, and H.R. Pappu. 2009. Molecular characterization of two Potato Virus S isolates from late blight resistant genotypes of potato (Solanum tuberosum). Archives of Virology 154:1861-1863. DOI 10.1007/s00705-009-0486-6.
  • Bag, S., K.L. Druffel, T. Salewsky, and H.R. Pappu. 2009. Nucleotide sequence and genome organization of the medium RNA of Iris yellow spot virus (genus Tospovirus, family Bunyaviridae) from the United States. Archives of Virology 154:715-718.
  • Bag, S., and H.R. Pappu. 2009. Symptomatology of Iris yellow spot virus in selected indicator hosts. Plant Health Progress. doi:10.1094/PHP-2009-0824-01-BR.
  • Bag, S., P. Rogers, R. Watson, and H.R. Pappu. 2009. First report of natural infection of garlic (Allium sativum) with Iris yellow spot virus in the United States. Plant Disease 93:839.
  • Bag, S., J. Singh, R.M. Davis, W..Chounet, and H.R. Pappu. 2009. Iris yellow spot virus in Nevada and Northern California. Plant Disease 93:674.
  • Pappu, H.R., and K.L Druffel. 2009. Use of conserved genomic regions and degenerate primers in a PCR-based assay for the detection of members of the genus CaulimovirusJournal of Virological Methods 157:102–104.
  • Evans, C.K., S. Bag, E. Frank, J. Reeve, C. Ransom, D. Drost, and H.R. Pappu. 2009. Natural infection of Iris yellow spot virus in Twoscale saltbush (Atriplex micrantha) growing in Utah. Plant Disease 93:430.
  • Sampangi, R., C. Almeyda-Beccarra, K.L. Druffel, S. Krishna Mohan, and H.R. Pappu. 2009. First report of natural infection of Penstemon acuminatus with Cucumber mosaic virus. Plant Disease 93:762.
  • Samuitiene, M., M. Navalinskiene, S.G. Eid, and H.R. Pappu. 2009. Dahlia mosaic-associated caulimoviruses in dahlia (Dahlia variabilis) in Lithuania. Plant Health Progress Online.doi:10.1094/PHP-2009-0302-01-BR.
  • Gieck, S.L., P.B. Hamm, N.L. David, and H.R. Pappu, 2009. First Report of Garlic virus B and Garlic virus D in Garlic in the Pacific Northwest. Plant Disease 93:431.
  • Evans, C.K., S. Bag, E. Frank, J. Reeve, C. Ransom, D. Drost, and H.R. Pappu. 2009. Green foxtail (Setaria viridis), a naturally infected grass host of Iris yellow spot virus in Utah. Plant Disease 93:670.
  • Pahalawatta, V., K.L. Druffel, and H.R. Pappu. 2008. A new and distinct species in the genus Caulimovirus exists as an endogenous plant pararetroviral sequence in its host, Dahlia variabilisVirology 376:253-257.
  • Pappu, H.R., K.L. Druffel, R. Miglino, and A. R. van Schadewijk. 2008. Nucleotide sequence and genome organization of a new and distinct caulimovirus associated with dahlia mosaic. Archives of Virology 153:2145–2148.
  • Segwagwe, A.T., M.L. Putnam, K.L. Druffel, H.R. Pappu, and K.C. Eastwell. 2008. Molecular characterization of a new tymovirus from Diascia ornamental plants. Archives of Virology 153:1495–1503.
  • Pappu, H.R., and M.E. Matheron. 2008. Characterization of Iris yellow spot virus from onion in Arizona. Plant Health Progress. doi:10.1094/PHP-2008-0711-01-BR.
  • Pappu, H.R., B.C. Hellier, and F.M. Dugan. 2008. Evaluation of the National Plant Germplasm System’s Garlic Collection for Seven Viruses. Plant Health Progress doi:10.1094/PHP-2008-0919-01-RS.
  • Ward, L.I., Z. Perez-Egusquiza, J.D. Fletcher, F.M. Ochoa Corona, J.Z. Tang, L.W.Liefting, E.J. Martin, B.D. Quinn, H.R. Pappu and G.R.G. Clover. 2008. First Report of Iris yellow spot virus on Allium cepa in New Zealand. New Disease Reports
  • Pappu, H.R., K.L. Druffel, and K.C. Eastwell. 2008. Canna yellow mottle virus in Canna in Washington State. Plant Disease 92:1136.
  • Krishnareddy, M., R. Usha Rani, Anil Kumar, K. Madhavi Reddy and H.R. Pappu. 2008. First Report of Capsicum chlorosis virus (Genus Tospovirus) infecting Chili Pepper (Capsicum annuum) in India. Plant Disease 92:1469.
  • Pahalawatta, V., K.L. Druffel, S.D. Wyatt, K.C. Eastwell, and H.R. Pappu. 2008. Genome structure and organization of a novel and distinct species of genus Caulimovirus (Family Caulimoviridae) associated with dahlia mosaic (pdf)Archives of Virology 153:733-738.
  • Huchette, O., C. Bellamy, R. Filomenko, B. Pouleau, S. Seddas, and H.R. Pappu. 2008. Iris yellow spot virus in Shallot and Onion in France. Plant Health Progress doi:10.1094/PHP-2008-0610-01-BR.
  • Pappu, H.R., K.R.W. Hammett, and K.L. Druffel. 2008. First report of Dahlia mosaic virus and Tobacco streak virus in dahlia (Dahlia variabilis) in New Zealand. Plant Disease 92:1138.
  • Mandal, B., A.S. Csinos, N. Martinez-Ochoa, and H.R. Pappu. 2008. A highly efficient and high throughput inoculation method for Tomato spotted wilt tospovirus. (pdf) J. Virological Methods 149:195-198.
  • Mandal, B., S. Mandal, A.S. Csinos, N. Martinez, A.K. Culbreath and H.R. Pappu. 2008. Biological and molecular analyses of the acibenzolar-S-methyl-induced systemic acquired resistance in flue-cured tobacco against Tomato spotted wilt virus. (pdf) Phytopathology 98:196-204.
  • Pappu, H.R., I.M. Rosales, and K.L. Druffel. 2008. Serological and molecular assays for rapid and sensitive detection of Iris yellow spot virus (Genus Tospovirus, Family Bunyaviridae) infection of bulb and seed onion crops. (pdf) Plant Disease 92: 588-594.
  • Hoepting, C.A., J. Allen, K. Vanderkooi, M. Hovius, H.R. Pappu, and M.R. McDonald. 2008. First Report of Iris yellow spot virus on Onion in Canada. (pdf) Plant Disease 92:318.
  • Miglino, R., A. Jodlowska, H.R. Pappu, and A.R. van Schadewijk, A. R. 2007. A highly sensitive and semi-automated method for genus-wide and species-specific detection of plant viruses of ornamental bulb crops (pdf)J. Virological Methods 146:155–164.
  • Pappu, H.R., and K.L. Druffel. 2007. First report of Streptocarpus flower break virus in the United States (pdf)Plant Disease 91:1361.
  • Sampangi, R.S., S. Krishna Mohan, and H.R. Pappu. 2007. New weed hosts of Iris yellow spot virus. (pdf) Plant Disease 91:1683.
  • Poole, G.J., H.R. Pappu, R.M. Davis, and T.A. Turini. 2007. Increasing outbreaks and impact of Iris yellow spot virus in bulb and seed onion crops in the Imperial and Antelope Valleys of California (pdf)Plant Health Progress. doi:10.1094/PHP-2007-0508-01-BR.
  • Mandal, B., M.L. Wells, N. Martinez-Ochoa, A.S. Csinos, and H.R. Pappu. 2007. Symptom development and distribution of Tomato spotted wilt virus in flue-cured tobacco. (pdf) Annals of Applied Biology 151: 67-75.
  • Pahalawatta, V., R. Miglino, K.L. Druffel, A. Jodlowska, A. R. van Schadewijk, and H.R. Pappu. 2007. Incidence and relative distribution of distinct caulimoviruses (Genus Caulimovirus, Family Caulimoviridae) associated with dahlia mosaic in Dahlia variabilis (pdf)Plant Disease 91:1194-1197.
  • Gieck, S.L., H.R. Pappu, P.B. Hamm and N.L. David. 2007. First report of Onion Yellow Dwarf Virus, Leek Yellow Stripe Virus, and Garlic Common Latent Virusin garlic in Oregon. (pdf) Plant Disease 91:461.
  • Nischwitz, C., H.R. Pappu, S.W. Mullis, A.N. Sparks, D.R. Langston, A.S. Csinos, and R.D. Gitaitis. 2007. Phylogenetic analysis of Iris yellow spot virus isolates from onion (Allium cepa) in Georgia and Peru (pdf)J. Phytopathology 155:531-535.
  • Schwartz, H.F., K. Otto, and H. R. Pappu. 2007. First report of Iris yellow spot virus in commercial leek (Allium porrum L.) in the United States (pdf)Plant Disease91:113.
  • Pahalawatta, V., K. Druffel and H.R. Pappu. 2007. Seed transmission of Dahlia mosaic virus in Dahlia pinnata(pdf)Plant Disease 91:88-91.
  • Hoepting, C.A., H.F. Schwartz, and H.R. Pappu. 2007. First report of Iris yellow spot virus in onion in New York (pdf)Plant Disease 91:327.
  • Miller, M, R. Saldana, M. C. Black, and H.R. Pappu. 2006.  First report of Iris yellow spot virus on onion (Allium cepa) in Texas (pdf)Plant Disease 90:1359.
  • Mandal, B., H.R. Pappu, A.S. Csinos, and A.K. Culbreath. 2006. Response of peanut, pepper, tobacco, and tomato cultivars to two biologically distinct isolates of Tomato spotted wilt virus (pdf)Plant Disease 90:1150-1155.
  • Pappu, H.R., L.J. du Toit, H.F. Schwartz and K. Mohan. 2006. Sequence diversity of the Nucleoprotein gene of Iris yellow spot virus (genus Tospovirus, family Bunyaviridae) isolates from the western region of the United States (pdf).Archives of Virology 151:1015-1023.
  • Pappu, H.R., B.C. Hellier and F.M. Dugan, 2006. Wild Allium spp as natural hosts of Iris yellow spot virus (pdf)Plant Disease 90:378.
  • Rosales, M., H.R. Pappu, L. López, R. Mora and A. Aljaro. 2005. Iris yellow spot virus in onion in Chile (pdf)Plant Disease 89: 1245.
  • Pappu, H.R., B.C. Hellier and F.M. Dugan, 2005. First report of Onion yellow dwarf virus, Leek yellow stripe virus and Garlic common latent virus in garlic in Washington State (pdf). Plant Disease 89: 205.
  • Pappu, H.R., S.D. Wyatt, and K. Druffel. 2005. Dahlia mosaic virus: Molecular detection and distribution in dahlia in the United States (pdf)HortScience 40: 697-699.
  • Crowe, F., and H.R. Pappu. 2005. Outbreak of Iris yellow spot virus on onion in seed crops in central Oregon (pdf). Plant Disease 89:105.
  • Riley, D.G. and H. R. Pappu. 2004. Tactics for Management of Thrips (Thysanoptera: Thripidae) and Tomato spotted wilt virus in tomato (pdf)Journal of Economic Entomology 97:1648-1658.
  • du Toit, L.J., H. R. Pappu, K. L. Druffel, and G. Q. Pelter. 2004. Iris yellow spot virus in onion bulb and seed crops in Washington State (pdf)Plant Disease 88:222.
  • Yang, H., P. Ozias-Akins, A. K. Culbreath, D. W. Gorbet, J. R. Weeks, B. Mandal and H. R. Pappu. 2004. Field evaluation of Tomato spotted wilt virusresistance in transgenic peanut (pdf)Plant Disease 88: 259-264.
  • Díaz-Pérez, J.C., K. D. Batal, D. Granberry, D. Bertrand, D. Giddings, and H.R. Pappu. 2003. Growth and yield of tomato plastic film mulches as affected by Tomato spotted wilt virus. HortScience 38:395-399.
  • McPherson, R.M., D.C. Jones, H.R. Pappu, and J.M. Moore. 2003. Reducing the risks of Tomato spotted wilt virus in tobacco with selected thrips control practices. J. Agric. Urban Entomol. 11-23.
  • Mandal, B., H. R. Pappu, A. K. Culbreath, C. C. Holbrook, D. W. Gorbet and J. W. Todd. 2002. Differential response of selected peanut genotypes to mechanical inoculation by Tomato spotted wilt virus. (pdf) Plant Disease 86: 939-944.


Providing diagnostics for growers and county faculty for a wide range of viruses of vegetables, small grains, legumes, and ornamentals.

Develop print and electronic educational and informational materials for stakeholders, delivers talks at stakeholder meetings of vegetables/legumes and ornamentals.

Presentations at Grower Meetings

  • Annual meeting of the Idaho-Eastern Oregon Onion Growers Association. Ontario, OR. February 6, 2007. “Managing Iris yellow spot virus epidemics in bulb and seed onion crops”.
  • Annual meeting of the Pacific Northwest Vegetable Association. Pasco, WA. November 17, 2007. “An update on thrips and Iris yellow spot virus”.
  • Annual meeting of the American Dahlia Society, September 5-9, 2007, St. Charles, IL. “Increasing diversity of viruses in dahlia and the implications for diagnosis and management”.
  • Annual meeting of the Pacific Northwest Vegetable Association. Pasco, WA. November 17, 2006. “Iris yellow spot virus: An update”.
  • National meeting of the American Dahlia Society, Seattle, WA. August 26-29, 2004. Presented a paper, “Diagnosis and management of viruses of dahlia”.
  • Annual meeting of the Pacific Northwest Vegetable Association. Pasco, WA. November 17, 2004. “Iris yellow spot virus on onions: Current status in Pacific Northwest and management options”.

List (pdf)

Diagnostic Images

Nursery/Landscape/Floral Crops


  • Schwartz et al., 2011. Onion Diagnostic Cards (pdf). Provided by Onion PIPE, a project supported by USDA NIFA Specialty Crops Research Initiative.
  • Pappu, H.R., R. Sampangi and S. Krishna Mohan. 2006. Symptoms of Iris yellow spot virus on onion. APSnet Image of the Week.
  • Hellier, B., H.R. Pappu, and F. Dugan. 2005. Symptoms of Iris yellow spot virus on wild onion. APSnet Image of the Week.
  • du Toit, L.J., Pelter, G.Q., and Pappu, H.R. 2003. Iris yellow spot virus. APSnet Image of the Week.
  • Mandal, B., H.R. Pappu, and A.S. Csinos. 2003. Suppressive effect of acibenzolar-S-methyl on Tomato spotted wilt virus. APSnet ‘Image of the Week’.
  • Pappu, H.R. 2000. Tomato spotted wilt virus on pepper. APSnet ‘Image of the Week’.
  • SCRI Onion Pests and Diseases (pdf)

Graduate Students


  • Cristian Olaya, Ph.D. student started in fall 2014
  • Lindani Moyo, Ph.D. student started in fall 2015
  • Afsha Tabassum, Ph.D. student started in fall 2015


  • Vihanga Pahalawatta. Ph.D. Graduated in summer 2007; Senior Scientist, Abbott Molecular Diagnostics, Des Plaines, IL
  • Sahar Eid. Ph.D. Graduated in summer 2010; Post-doctoral Fellow, University of Idaho,Moscow, ID
  • Noma Chingandu, MS. Grauated in summer 2012; PhD student, University of Arizona, Tucson, AZ
  • Christie Almeyda, Ph.D. Graduated in summer 2012; Post-doctoral fellow, NC State University
  • Yu-Hsuan Lin, Ph.D. Graduated in summer 2012; Post-doctoral fellow, USDA-ARS and Cornell University, Ithaca, NY
  • Sudeep Bag, Ph.D. Graduated in spring 2013. Post-doctoral fellow, USDA-ARS and UC Davis, Davis, CA
  • Khalid Naveed, Ph.D. Graduated in fall 2013. Assistant Professor, University of Agriculture, Faisalabad, Pakistan
  • Diwaker Tripathi, Ph.D. Molecular Plant Sciences. Graduated in spring 2014. Post-doctoral fellow, WSU, Pullman, WA
  • Ying Zhai, Ph.D. Graduated in summer 2014. Post-doctoral fellow, WSU, Pullman

Member, Graduate Student Advisory Committees:


  • Chiti Agrawal,PhD in Plant Pathology. Started in fall 2016
  • Joeseph deShields, MS in Plant Pathology. Started in fall 2016
  • Kanwardeep Singh, PhD in Crops and Soils. Started in fall 2014


  • Madhu Kappagantu, Ph.D. in Plant Pathology, Graduated in fall 2017
  • Abby Beisinger, MS in Plant Pathology, Graduated in spring 2017
  • Jeff Bullock, PhD in Plant Pathology. Graduated in fall 2015
  • Tim Ross-Elliott, PhD in Molecular Plant Sciences. Started in fall 2016
  • Shaonpius Mondal, PhD in Entomology, Univ of Idaho. Graduated in fall 2014
  • Nuan Wen, PhD in Molecular Plant Sciences, Graduated in spring 2014
  • Claudio Osario, PhD in Crops and Soil Sciences, Graduated in fall 2013
  • Dan Villamor, PhD in Plant Pathology. Graduated in summer 2012
  • Deepak Srestha, MS in Entomology, Univ of Idaho. Graduated in summer 2012
  • Olufemi Alabi, PhD in Plant Pathology. Graduated in fall 2009
  • Jeremy Buchman, MS in Entomology, Graduated in spring 2011
  • Josh Lloyd, MS, University of Idaho. Graduated in 2006
  • Catalina Leger. M.S. in Plant Pathology. Graduated in 2006
  • Christopher Hammond. M.S. in Plant Pathology. Graduated in 2004
  • Leigh Anne Harrison. M.S. in Plant Pathology. Graduated in 2006
  • Hui Hou. M.S. in Plant Pathology. Graduated in 2006
  • Amogelang Segwagwe. Ph.D. in Plant Pathology. Graduated in 2007

Visiting Scientists/Post-Doctoral Fellows

  • Dr. Aflaq Hamid, Assistant Professor, J & K University of Science and Technology, SriNagar, J&K, India. Sept 2016 to Sept 2017.
  • Dr. Gaurav Raikhy, Post-doctoral Associate, Sept 2012 to Nov 2015.
  • Dr. SV. Ramesh, Principal Scientist, National Center for Soybean Research, Indore, India. Sept. 2013 to Sept. 2014.
  • Dr. Eldar Mustafayev, Assistant Professor, Azerbaijan Academy of Sciences, Baku, Azerbaijan. Sept to Dec 2013.
  • Dr. Suresh Gawande, Principal Scientist, National Research Center for Onion and Garlic, Pune, India. Sept to Dec 2013.
  • Ms. Romana Iftikhar, PhD student, National Institute of Biotechnology and Genetic Engineering, Faisalabad, Pakistan. November 2013 to April 2014.
  • Dr. Vikas Koundal, Post-doctoral Associate, June 2010 to May 2012.
  • Dr. Pawan Kumar Sharma, Senior Scientist, ICAR Research Complex for the NEH Region, Imphal, Manipur, India. November 2010 to May 2011.
  • Dr. Neena Mitter, Principal Biotechnologist, Department of Primary Industries, and University of Queensland, Brisbane, Australia. November 2009.
  • Dr. N. Manickam, Scientist-EI, Environmental Biotechnology Section, Industrial Toxicology Research Centre, Lucknow, India. July-August, 2009, on a Norman Borlaug Fellowship.
  • Dr. R. Kannan, Associate Professor (Plant Pathology), Department of Plant Protection, Agricultural College and Research Institute, Killikulam, Tamil Nadu, India, January 2009.
  • Dr. Roberto Miglino, Dutch Bulb Inspection Service, Lisse, The Netherlands, August 2008.
  • Mr. Joaquin Diaz, Staff Scientist, Mexican Department of Agriculture, August 2007.
  • Dr. Marlene Rosales, Staff Scientist, Instituto de Investigaciones Agropecuarias, Centro Regional de Investigación La Platina, Santiago, Chile. September 2005.
  • Dr. Celia Chalam, Staff Scientist, National Bureau of Plant Genetic Resources, New Delhi, India. October to December 2003.
  • Dr. Bikash Mandal, Senior Scientist, Indian Agricultural Research Institute, New Delhi, India May, 2000 to April 2002.
  • Dr. A. Wangai, Staff Scientist, Kenyan Agricultural Research Institute, National Plant Breeding Research Center, Njoro, Kenya (Fulbright Fellow) September 1998 to September 1999.
  • Dr. A.I. Bhat, Junior Scientist, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India; April 1998 to April 1999.
  • Dr. R.K. Jain, Head, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, India. January 1997 to January 1998.
  • Mr. Hong-Soo Choi, Staff Scientist, Plant Pathology Division, Dept. of Crop Protection, National Institute of Agricultural Science and Technology, Suwon, Republic of Korea November-December, 1998).

Research and outreach activities are supported by

USDA-CSREES Western Region IPM Center, USDA-CSREES Specialty Crops Research Initiative, USDA-CSREES Critcial and Emerging Issues Program, USDA-FAS, USDA-RAMP, USDA Northwest Nursery Crop Research Center, W-SARE, WSU Agricultural Research Center, WSU Office of Research, WSU Office of International Programs, American Dahlia Society, Washington State Potato Commission, Washington Wheat Commission, Washington State Commission for Pesticide Registration, Pacific Northwest Vegetable Association, Columbia Basin Vegetable Seed Association, California Garlic and Onion Research Advisory Board, Nevada Onion Commission, and the Idaho State Department of Agriculture, Nursery and Florist Advisory Committee/Idaho Nursery & Landscape Association.