Scott A. Isard, Ph.D.

  • Professor
Scott A. Isard, Ph.D.
205 Buckhout Lab (office)

University Park, PA 16802
Work Phone: 814-865-6290
Fax: 814-863-7217

Areas of Expertise

  • Aerobiology
  • Food security
  • Integrated Pest Management


  1. B.A., University of Wisconsin
  2. M.A., University of Pennsylvania
  3. M.S., Education, University of Pennsylvania
  4. Ph.D., Indiana University

Areas of Interest

Integrated Pest Management, Aerobiology, movement and dispersal of organisms, meteorology, field measurement


Escape and dispersal of spores.  Research was supported by a grant from the National Science Foundation for 2011-2015: "Dispersal of Spores within and above Plant Canopies"

Collaboration: Marcelo Chamecki, Meteorologist, PSU and Heidi Nepf, MIT

Mission: The goal of this research is to use large eddy simulation (LES) of atmospheric transport to evaluate risk of spore deposition with distance from various sources (crops) of varying field size in simple and complex terrain. 

Isard’s lab: We studied spore escape from wheat fields infected with leaf rust Puccinia triticina.  To do this we monitored plant height, LAI, and spore density throughout the study period.  We measured the vertical profile of air temperature, RH and wind speed at 5 levels on a 10 m tower in the field.  We collected spores at 3 levels from a 13 tower transect through the center of the field over 30 minute periods while we were also monitoring the 3-D wind field at 50 hz within and above the field.

Modeling of spore aerobiology in agricultural settings continues after the termination of the NSF grant with a focus on theoretical models of spore escape from plant canopies and deposition downwind.

B.  Recent Publications 

Ryan, S.F., N.L. Adamson, A. Aktipis, L.K. Andersen, R. Austin, L. Barnes, M.R. Beasley, K.D. Bedell, K. Bidell, S. Briggs, B. Chapman, C. Cooper, J. Corn, N.G. Creamer, J.A. Delborne, P. Domenico, E. Driscoll, J. Goodwin, A. Hjarding, J.M. Hulbert, S. Isard, M.G. Just, K. Kar Gupta, M.M. López-Uribe, J. O’Sullivan, J. Landin, E.A. Landis, E.A. McKenney, A.A. Madden L.M. Nichols, S. Ramaswamy, B. Reading, S. Russell, N. Sengupta, L. Shell, J.K. Sheard, D.D. Shoemaker, D.M. Sorger, C. Starling, S. Thakur, R. Vatsavai, M. Weinstein, P. Wimfrey, and R.R. Dunn. 2018. The role of citizen science in addressing grand challenges in food and agricultural research. Proceedings of the Royal Society B: Biological Sciences 285:

Mueller, D.S., A.J. Sisson, R. Kempker, S. Isard, C. Raymond, A.J. Gennett, W. Sheffer and C.A. Bradley. 2018 Scout, Snap, and share: First impressions of plant disease monitoring using social media.  Plant Disease 102: 1681-1686.

Tinsley, N.A., J.L. Spencer, R.E. Estes, K.A. Estes, A.L. Kaluf, S.A. Isard, E. Levine and M.E. Gray. 2018 Multi-year surveys reveal significant decline in western corn rootworm densities in Illinois soybean fields. American Entomologist 64: 112-119.

Willbur, J.F., M. L. Fall, C. Bloomingdale, A.M. Byrne, S.A. Chapman, S.A. Isard, R.D. Magarey, M.M. McCaghey, B.D. Mueller, J.M. Russo, J. Schlegel, M.I. Chilvers, D.S. Mueller, M.Kabbage, and D.L. Smith. 2017  Weather-based models for assessing the risk of Sclerotinia sclerotiorum apothecial presence in soybean (Glycine max) fields.  Plant Disease DOI: 10.1094/PDIS-04-17-0504-RE

Galan, C., A Ariatti, M. Bonini, B. Clot, B. Crouzy, A. Dahl, C. Fernandez-Gonzalez, G. Frenguelli, R. Gehrig, S. Isard, E. Levetin, D.W. Li, P. Mandrioli, C.A. Rogers and M. Thibaudon. 2017. Recommended terminology for aerobiological studies. Aerobiologia 33:293–295.

Margarey, R. and S.A. Isard. 2017. A troubleshooting guide for mechanistic plant pest forecast models.  Journal of Integrated Pest Management 8:1-7.

Isard, S. A. and M. Chamecki, 2016. A physically based theoretical model of spore deposition for predicting spread of plant diseases.  Phytopathology, 106: 244-253.

Pan, Y., M. Chamecki, S.A. Isard and H.M. Nepf, 2015. Dispersion of particles released at the leading edge of a crop canopy.  Agricultural and Forest Meteorology 211-212: 37-47.

Sanatkar, M.R., C. Scoglio, B. Natarajan, S.A. Isard and K.A. Garrett, 2015. History, epidemic evolution, and model burn-in for a network of annual invasion:  soybean rust.  Phytopathology 105: 947-955.

Kelly, H.Y., N.S. Dufault, D.R. Walker, S.A. Isard, R.W. Schneider, L.J. Giesler, D.L. Wright, J.J. Marois, and G.L. Hartman, 2015. From select agent to an established pathogen: The response to Phakopsora padchyrhizi (soybean rust) in North America.  Phytopathology 105: 905-916.

Pan, Y., M. Chamecki, and S.A. Isard, 2014. Large-eddy simulation of spore dispersion inside the canopy roughtness sublayer, Journal of Fluid Mechanics 753: 499-534

Sikora, E. J., Allen, T. W., Wise, K. A., Baniecki, J., Bergstrom, G., Bradley, C., Brown-Rytlewski, D., Chilvers, M., Coker, C., Damicone, J., DeWolf, E., Dorrance, A., Dufault, N., Esker, P., Faske, T., Giesler, L., Grau, C., Golod, J., Grybauskus, A., Franc, G., Hammerschmidt, R., Hartman, G., Henn, A., Hershman, D., Hollier, C., Isakeit, T., Isard, S., Jacobson, B., Jardine, D., Kemerait, B., Koenning, S., Malvick, D., Markell, S., Marois, J., Monfort, S., Mueller, D., Mueller, J., Mulrooney, B., Newman, M., Osborne, L., Padgett, G.B., Ruden, B., Rupe, J., Schneider, R., Schwartz, H. Shaner, G., Singh, S., Stromberg, E., Sweets, L., Tenuta, A., Trippett, C., Vaiciunas, S., Yang, X.B., Zidek, J., 2014. A coordinated effort to manage soybean rust in North America: a success story in soybean disease monitoring. Plant Disease 98: 864-875..

Gleicher, S.C.., M. Chamecki, S.A. Isard, Y. Pan, and G.G. Katul, 2014. Interpreting three-dimensional spore concentration measurements and escape fraction in a crop canopy using a coupled Eulerian-Lagrangian stochastic model, Agricultural and Forest Meteorology 194: 118–131.

Pan, Y., S.A. Isard, and M. Chamecki. 2013. Dispersion of heavy particles emitted from area sources in the unstable atmospheric boundary layer. Boundary Layer Meteorology 146, 235-256.

Luck, J., Campbell, I., Magarey, R., Isard, S., Aurambout, J-P., Finlay, K. 2013.  Climate change and plant biosecurity–Implications for policy. Plant Biosecurity Handbook.  In “Principles and Practices for the Identification, Containment and Control of Organisms that Threaten Agriculture and the Environment Globally.” Gordh, G; McKirdy, S. (Eds.) Springer, NY.  760 p.

Neufeld, K.N., S.A. Isard, and P.S. Ojiambo, 2013. Quantifying the relationship between disease severity and concentration and escape of Pseudoperonospora cubensis sporangia from a cucumber canopy.  Plant Pathology 62. 1366-1377.

Chamecki, M., N.S. Dufault, and S.A. Isard. 2012. Atmospheric dispersion of wheat rust spores: a new theoretical framework to interpret field data and estimate downwind dispersion. Journal of Applied Meteorology and Climatology 51: 672-685.

Sutrave, S., C. Scoglio, S.A. Isard, J.M.S. Hutchinson, and K.A. Garrett. 2012. Identifying highly connected counties compensates for resource limitations when evaluation national spread of an invasive pathogen.  PLoS ONE 7: e37793. doi:10.1371/journal.pone.0037793.

Isard, S.A., C.W. Barnes, S. Hambleton, A. Ariatti, J.M. Russo, A. Tenuta, D.A. Gay, and L.J. Szabo.  2011. Predicting seasonal soybean rust incursions into the North American continental interior using sentinel plot monitoring, spore trapping, and aerobiological modeling. Plant Disease.

Chamecki, M., S.C. Gliecher, N.S. Dufault, and S.A. Isard, 2011. Diurnal variation in settling velocity of pollen released from maize and consequences for atmospheric dispersion and cross-pollination. Agricultural and Forest Meteorology151: 1055–1065.

Isard, S.A. and J.M. Russo. 2011. Risk assessment of aerial transport of rust pathogens to the Western Hemisphere and within North America. 2011 Borlaug Global Rust Initiative Technical Workshop, in press.

Russo, J. M. and S. A. Isard, 2011.  Online Aerobiology Process Model. In Pierce F.J. (ed.), GIS Applications in Agriculture.  Volume 3: Invasive Species. CRC press, 159-166.  

Marchetto, K. M., E. Jongehans, K. Shea and S. A. Isard, 2010.  Plant Spatial Arrangement Affects Projected Invasion Speeds of Two Invasive Thistles.  Oikos 119: 1462-1468.

Dufault, N.S. and Isard S. A.  2010.  A portable rainfall simulator for evaluating the wet deposition of plant pathogens.  Applied Engineering in Agriculture 26: 71-78.

Dufault, N.S., S.A. Isard, J.J. Marois, and D.L. Wright.  2010.  Wet deposition of Phakopsora pachyrhizi urediniospores into a soybean canopy.  Canadian Journal of Phytopathology 32: 162-169.  

Dufault, N.S., S.A. Isard, J.J. Marois, and D.L. Wright.  2010. Removal of wet deposited Phakopsora pachyrhizi urediniospores from soybean leaves by subsequent rainfall. Plant Disease 94: 1336-1340.

Dauer, J. T., D. A. Mortensen, E. C. Luschei, S. A. Isard, E. Sheilds, and M. J. Van-Gessel. 2009.  Ascent and Transport of Conyza canadensis seed in the Lower Atmosphere.  Agricultural and Forest Meteorology 149: 526-534.

Isard, S. A., S. Fleischer, D. A. Mortensen, and E.D. DeWolf.  2008.  Aerobiology and IPM.  In Radcliffe, E.B. and W.D. Hutchinson, (eds.), Integrated Pest Management:  Concepts, Tactics, Strategies, and Case Studies.  Cambridge Press.

Park, J., B. Park, N. Veeraraghavan, J.E. Blair, D.M. Geiser, S. Isard, M.A. Mansfield, E. Nikolaeva, S.-Y. Park, J. Russo, S.H. Kim, M. Greene, K.L. Ivors, Y. Balci, M. Peiman, M.D. Coffey, K. Jung, Y.-H. Lee, A. Rossman, D. Farr, E. Cline, N.J. Grünwald, D.G. Luster, J. Schrandt, F. Martin, I. Makalowska, and S. Kang,  2008.  Phytophthora Database v.1.0: A cyberinfrastructure supporting the identification and monitoring of Phytophthora.  Plant Disease 92: 966-972.

Isard, S. and J. Russo, 2008. Sentinel plots in the United States:  monitoring the seasonal spread of soybean rust in North America.  Chapter 5 in Dorrance, A., M. Draper, and D. Hershman, Using Foliar Fungicides to Manage Soybean Rust,

Isard, S.A., J.M. Russo, and A. Arriatti, 2007.  Aerial transport of soybean rust spores into the Ohio River Valley during September 2006.  Aerobiologia 23:271-282.

DeWolf, E.D. and S.A. Isard, 2007. Disease cycle approach to plant disease prediction.  Annual Review of Phytopathology 45: 9.1-9.18.

Isard, S.A., R.L. Schaetzl, and J. Andresen, 2007.  Soils cool as climate warms in Great Lakes Region, USA 1951-2000. Annals of the Association of American Geographers: 97; 467-476.  

Fleischer, S. G. Payne, T. Kuhar, A. Herbert, Jr., S. Malone, J. Whalen, G. Dively, D. Johnson, J.A. Hebberger, J. Ingerson-Mahar, D. Miller and S. Isard, 2007.  H. zea trends from the northeast:  Suggestions towards collaborative mapping of migration and pyrethroid susceptibility.  Plant Health Progress. doi:10.1094/PHP-2007-0719-03-RV.

Isard, S.A., N.S. Dufault, M.R. Miles, G.L. Hartman, J.M. Russo, E.D. De Wolf, and W. Morel, 2006.  The effect of solar irradiance on the mortality of Phakopsora pachyrhizi urediniospores.  Plant Disease 90: 941-945.

Isard, S.A., Russo, J.M. and DeWolf, E.D., 2006.  The establishment of a national pest information platform for extension and education.  Online, Plant Health Progress, doi:10.1094/PHP-2006-0915-01-RV.

Isard, S.A., S.H. Gage, P. Comtois, and J. Russo, 2005.  Principles of aerobiology applied to soybean rust as an invasive species.  BioScience 55: 851-862.

Schaetzl, R. and S.A. Isard, 2005.  Modeling Soil Temperatures and the Mesic-Frigid Boundary in the Great Lakes Region, 1951-2000, Soil Science Society of America Journal 69: 2033-2040.

Magarey, R. and S.A. Isard, 2005.  Model and dispersal for Asian soybean rust.  Pages 21-22 in Proceedings of the Illinois Crop Protection Technology Conference, University of Illinois at Urbana-Champaign.

Spencer, J.L., T.R. Mabry, E. Levine, and S.A. Isard, 2005.  Movement, Dispersal, and Behavior of Western Corn Rootworm Adults in Rotated Corn and Soybean Fields. Pages 121-144 in Vidal, S. U. Kuhlmann, and C.R. Edwards, eds. Western Corn Rootworm: Ecology and Management. CAB Publishing.  



Integrated Pest Information Platform for Extension and Education (iPiPE).  Activities supported by a grant from the United Soybean Board for 2012-2015: “People support for the iPiPE” and by a $7 million, 5 yr grant from the USDA National Institutes of Food and Agriculture AFRI Food Security Challange Area grant for 2015-2020.

Collaborators: Joseph Russo (Senior Scientist and President, ZedX Inc., Belefonte, PA), Jim VanKirk (Director, SE IPM Center, NCSU), Roger Magarey (Senior Researcher, NCSU and Cooperator with USDA-APHIS-PPQ-CPHST-PERAL), Julie Golod (iPiPE National Coordinator, PSU) and many others.

Publication:  Isard, S.A., J.M. Russo, R.D. Magarey, J. Golod and J.R. VanKirk, 2015. Integrated Pest Information Platform for Extension and Education (iPiPE): Progress through sharing. Journal of Integrated Pest Management 6(1): 15; DOI: 10.1093/jipm/pmv013

Mission: Food security is best served by a national infrastructure of private and public professionals who routinely monitor crop health and pest incidence then translate this knowledge to a shared platform enabling rapid dissemination of mitigation measures to limit crop loss. The Integrated Pest Information Platform for Extension and Education (iPiPE) provides such an infrastructure with cyberage tools, information products and expert commentary for detection and management of new, foreign, or emerging target pests and endemic pests that threaten U.S. crops. By categorizing pests, data, and users, it enables sharing observations while protecting privacy of individuals, companies, and government agencies. 

Goals and Objectives: The iPiPE is designed to be a comprehensive IT solution for collection, management, and delivery of crop and pest observations, derivative informational products (e.g., observation and predictive maps), and expert commentary. As a Web-based platform potentially serving all agricultural stakeholders, it will contribute substantially to the USDA National Institute of Food and Agriculture (NIFA) Agriculture and Food Research Initiative (AFRI) Food Security Challenge (FSC) area priority to “improve prevention, early detection, rapid diagnosis, containment, mitigation and recovery from new, foreign, or emerging pests and diseases of crops.” The iPiPE also supports the aim of the USDA National IPM Road Map to reduce adverse environmental effects from pests and related pest management practices and to improve cost benefit analyses through the adoption of IPM practices (USDA 2013).

      The iPiPE CAP has two interrelated goals. The first is to empower agricultural stakeholders to contribute their pest observations to a common database so that these data and information products derived from them can be effectively used for managing pests. The second goal is to establish an infrastructure of stakeholders, data, and tools linked by the Web to deliver observations for early detection and rapid diagnosis of unanticipated, new, foreign, and emerging pests threatening the nation’s crops. Shared pest observations in near real-time among large numbers of producers and their consultants are required to achieve these goals. Sharing pest observations constitutes an important change in stakeholder behavior and is being accomplished through a set of priority Crop-Pest Programs supported by the iPiPE platform. Each Crop-Pest Program—focused on a single crop and associated pests in a production region—is comprised of a Coordinator, other contributing extension professionals, undergraduate students, and stakeholders. Program stakeholders include producers and scouts who provide pest observations and benefit from iPiPE outputs that inform pest management decision-making. The plan for achieving the iPiPE goals is composed of extension, education, and research objectives:

1.  Engage extension professionals to encourage and facilitate stakeholders who collect data (e.g., growers and their crop consultants) to submit observations on new, foreign, and emerging pests (pathogens, insects, and weeds) as well as important endemic pests and their hosts to the iPiPE. Extension professionals coordinate extension and education activities in their production region for a single crop that is at high risk for one or more new, foreign, or emerging pests. They enlist assistance from other extension professionals and selected university, state, and federal employees throughout the production region. The aim is to create 32 Crop-Pest Programs between 2015-2019 coordinated by extension professionals from as many states as feasible.

2.  Recruit and train undergraduate student interns to: (i) become familiar with the functionality of the iPiPE; (ii) identify in daily observations submitted by crop consultants and growers pests not endemic to a production region; (iii) detect errors in identification of endemic pest observations submitted; (iv) work with extension professionals to provide up-to-date pest management guidelines, commentary, and risk assessments; and (v) receive training in food security concepts. Student interns, working with extension professionals, are responsible for providing feedback to growers and consultants about pests commonly misidentified and new to a production region. They develop and disseminate educational materials through social media tools hosted by the iPiPE platform. Typically, two student interns work in each Crop-Pest Program each summer, also training and working in a local pest diagnostic laboratory (e.g., National Plant Diagnostic Network). Instructional webinars for interns and extension professionals are held each year before the growing season. An important outcome is to train 64-128 undergraduate students in extension activities and food security associated with the iPiPE by providing extensive hands-on experiences that teach the value of shared pest observations and derivative informational products.

3.  Conduct research on targeted new, foreign, and emerging pests  iPiPE research employs advanced models developed for research and operational forecasting by the lead PD and PIs. Collectively, results from these models provide an integrated picture of physiological, phenological, and aerobiological processes that define pest-crop dynamics. Models are linked to historical weather data to quantify risk associated with pests in production areas and with “pathway” data to identify likely points of entry into the U.S. and subsequent movement of new, foreign, and emerging pests.

4.  Develop new and improved iPiPE IT tools to accommodate the large numbers of observations, and their derivative products (e.g., maps, commentaries, risk assessments, alerts, and educational materials for new, foreign, or emerging pests and other important endemic pests). The iPiPE uses mobile apps, accommodating new technologies as they become available, for product delivery to participants. The improved public interface provides a greater variety of maps, commentaries, alerts, and guidelines to iPiPE participants.

5.  Create a national pest observation depository. The iPiPE pest databases will be transferred after the period of operational use (starting in 2016) to the University of Georgia, Center for Invasive Species and Ecosystem Health (Bugwood, These databases will contribute to research requiring geographically-extensive, multi-year, pest observations. This research is necessary for developing IPM strategies in the future to address food security concerns associated with known as well as unanticipated new, foreign, and emerging pests.


Scott Isard currently teaches Atmospheric Environment: Growing in the Wind in the Fall semester each year.  This GN class is cross-listed as AGECO 122 and METEO 122.

GROWING IN THE WIND is for non-science majors who are interested in learning about the atmospheric environment and its influence on animals, plants, and humans.  It is about how processes at the ground surface and in the atmosphere govern weather conditions on the Earth.  Growing in the Wind focuses on five major weather elements:  energy, temperature, moisture, pressure, and wind.  Emphasis is given to human impacts on weather and climate and the influence of weather on plants and animals.  The course is organized around the central theme that the unequal distribution of incoming solar energy (both spatially and temporally) produces temperature and pressure contrasts at the Earth’s surface and in the atmosphere that in turn cause storms and control the weather.

No prerequisites are required.  A sincere interest in agriculture and/or the environment helps.

AGECO/METEO 122 satisfies General Education – Natural Science requirements

Outline and Listing of Major Topics

a.     Introduction to the atmosphere (topics: basic physical characteristics of planet earth that impact weather; composition and layers of the atmosphere; ozone depletion)

b.    Heating earth’s surface and atmosphere (topics: earth-sun geometric relationships; concepts of energy, heat, and temperature; solar and terrestrial radiation exchanges)

c.    Temperature (topics:  temperature controls; global patterns of temperature; global warming and the greenhouse effect)

d.    Biometeorology (topics: heat unit concept; phenology and plant growth; atmospheric effects on animals; human comfort indices)

e.    Atmospheric moisture (topics: moisture in the atmosphere; lifting and stability; forms of condensation and precipitation; water balance computations; acid rain; weather modification)

f.    Air pressure, winds, and global circulation regimes (topics: scales of motion; global circulation models; Hadley cells; westerlies; El Nino and the southern oscillation)

g.    Air masses and storms (topics: air mass classification; thunderstorms; tornadoes; middle latitude cyclones; hurricanes)

h.    Climate of world ecoregions (topics: tropical middle latitude polar and highland climates; climate change)

i.    Aerobiology (topics: atmospheric pathways for invasive species; take-off, horizontal translation, and descent processes; aerobiology models)

Course Objectives
By the end of the semester, students will be able to describe and discuss a) the effect of weather elements on plants and animals, b) how the major weather elements interact to govern storms, daily weather, and climate, and 3) how humans are changing our atmospheric environment.  This capability will be achieved through a series of active learning activities that reinforce the concepts and information presented in lecture and the textbook/CD.  Three research projects will involve information gathering using the Internet and library.  Students will develop critical thinking skills by using both inductive and deductive reasoning to synthesize and analyze their research findings.  Course activities will require students to discuss the material they have gathered and explain their analysis both in writing and oral communications.  The projects will require computations, quantitative thinking and interpretation of data, graphs, and results of calculations.  The research projects/class presentations will also engage students in collaborative learning and teamwork.

Evaluation Methods
Students will be evaluated on the basis of their performance on 3 exams, 3 research/writing projects, reading and CD unit quizzes, short “pop” lecture quizzes, and their participation in classroom discussions.  The exams are multiple choice and cover material from lecture and the textbook/accompanying CD.  Students will take Open Book Chapter Quizzes and CD Unit Quizzes on ANGEL.  Students will be given 10 minutes to take a quiz and they may take each quiz up to 3 times.  The quizzes will be “turned off” at appropriate times requiring students to keep up to date with reading and CD materials.  There will be 5-question, unannounced (“pop”), multiple choice quizzes at the end of some lectures designed to entice students to attend classes regularly.  Students will maintain a Weather Log for their “home town” during one week of the semester that will require them to gather hourly meteorological data from Internet sources and using it to address a series of questions.  Students will also construct and analyze an annual Water Budget for irrigation scheduling and reservoir water management from monthly temperature and precipitation data for their home town that they download from the Internet.  For two periods the classroom will be turned into an active learning environment where students will work together on their water budgets.  Near the end of the course, students will again work in small teams (2 or 3 individuals) to research the causes and human/ecosystem impacts of an important weather event that has occurred in the preceding year.  Grades for the final project will be based on the content of an annotated Powerpoint research report and an oral presentation (10 minute presentation involving all team members with a few minutes for questions) of their findings to the class.