Nathan Kleczewski


  • 2009 Ph.D. Plant Pathology, The Ohio State University.

Dissertation focused on integration of phytochemical/physiological defense theory in trees and integration with carbon-based models of mycorrhizal regulation.

  • 2004 B.S. Plant Ecology and Organismal Biology, The University of Wisconsin-Oshkosh (Summa Cum Laude)

Duties:  Statewide research and extension responsibilities for disease management of field crops

The goal of my research/extension program is to improve the management of diseases and productivity of field crops in Delaware.  My research program evaluates novel control strategies as components of the integrated management of corn, soybeans, wheat, and barley as well as select vegetable crops.  I work closely with other scientists to conduct research relevant to Delaware and the surrounding regions.  Results of my work are shared with regional stakeholders and are presented in peer-reviewed scientific journals, extension publications, conferences, and meetings.  Educational programs are aimed at increasing awareness, knowledge, and expertise in plant pathology of certified crop advisers, producers, and other stakeholders.

Current research:

  • Best management practices for Fusarium Head Blight of wheat and barley
  • Profitable management of foliar diseases of wheat
  • Foliar diseases of corn and their relationship to stalk and root rots
  • Fungicide resistance development in foliar diseases of corn and soybean
  • Soybean Necrotic Vein Virus
  • Profitability of fungicide use in double crop soybean
  • Assessment of fungicide and biological disease control programs in field crops and select vegetables and variety trial evaluation.


2014 The American Phytopathological Society

APS Leadership Institute Fellowship

2008  The Ohio State University Department of Plant Pathology

C. C. Allison Award for Research and Service

2007 American Phytopathological Society

Kenneth Barker Student Travel Award

2004 University of Wisconsin-Oshkosh

Outstanding Biology Major Award

2003 University of Wisconsin-Oshkosh

-Leslie-Allen Fellowship in Ecology and Field Biology

-Excellence in Scholarship Award

2001 University of Wisconsin-Oshkosh

Outstanding Student in General, Organic, and Biochemistry

Memberships and Service

American Phytopathological Society

NCERA 137: Soybean Diseases

NCERA 184: Wheat Diseases

Corn Disease Working Group

Southern Soybean Disease Working Group

Sigma Xi

Reviewing Activities

American Journal of Botany

Crop Protection

Ecological Letters

Fungal Ecology

Letters in Applied Microbiology

Journal of Medicinal Plants Research

Journal of Bacteriology Research

Microbial Ecology

Plant Disease

Plant and Soil

Publications (Peer Reviewed)

Manamgoda, D.S., A. Minnis, N.M. Kleczewski, S.L. Flory, L.A. Castlebury, and K.D. Hyde. 2013. Bipolaris drechsleri sp. nov. Fungal Planet Description Sheets 213:26.

Minnis A., A.Y. Rossman, N.M. Kleczewski and S.L. Flory. 2012.  Bipolaris microstegii sp nov. Fungal Planet Description Sheets 129: 151.

Bauer J. T., N. M. Kleczewski, J. D. Bever, K. Clay and H. L. Reynolds. 2012. Nitrogen-fixing bacteria, arbuscular mycorrhizal fungi and the productivity and structure of prairie grassland communities. Oecologia 170(4) 1089-1098.

Kleczewski N.M. and D. Egel. 2012.  Evaluation of triploid watermelon lines for resistance to Fusarium wilt, 2011.  Plant Disease Management Reports.

Kleczewski N.M., S. L. Flory and K. Clay. 2012. Variation in pathogenicity and host range of Bipolaris sp. causing leaf blight disease on the invasive grass Microstegium vimineum. Weed Science 60(3):486-493.

Kleczewski N. M., J. T. Bauer, J. D. Bever, K. Clay and H. L. Reynolds. 2012. A survey of endophytic fungi of switchgrass (Panicum virgatum) in the Midwest, and their putative roles in plant growth. Fungal Ecology 5(5):521-529.

Kleczewski N.M., D.A.Herms and P. Bonello. 2012. Nutrient and water availability alter belowground patterns of biomass allocation, carbon partitioning, and ectomycorrhizal abundance in Betula nigra. Trees: Structure and Function 26(2) 525-533.

Kleczewski N. M. and D. S. Egel, 2011. A diagnostic guide for Fusarium wilt of watermelon. Online. Plant Health Progress. doi:10.1094/PHP-2011-1129-01-DG.

Flory, S.L., N.M. Kleczewski, and K. Clay. 2011. Ecological consequences of pathogen accumulation on an invasive grass. Ecosphere 2(10):12 pp.

Kleczewski N. M. and S. L. Flory. 2010. A new leaf blight disease on the invasive grass Microstegium vimineum caused by a Bipolaris sp. Plant Disease 94(7): 807-811.

Kleczewski N. M., D.A.Herms, and P. Bonello. 2010. Effects of soil type, fertilization and drought on carbon allocation to root growth and partitioning between secondary metabolism and ectomycorrhizae of Betula papyrifera. Tree Physiology 30(7):807-817.

Publications (Extension)

Kleczewski, N.M. 2014.  Fusarium Head Blight of Small Grains.  University of Delaware Cooperative Extension Factsheet.  Available at:

Kleczewski, N.M. 2014.  Gray Leaf Spot on Corn.  University of Delaware Cooperative Extension Factsheet.  Available at:

Kleczewski, N.M. 2014. Stalk Rots on Corn.  University of Delaware Cooperative Extension.  Available at:

Kleczewski, N.M. 2014. Frogeye Leafspot of Soybean.  University of Delaware Cooperative Extension Factsheet.  Available at:

Kleczewski, N.M. 2014. Anthracnose Leaf Blight and Stalk Rot of Corn.  University of Delaware Cooperative Extension Factsheet.  Available at:

Kleczewski, N.M. et al. 2014.  Commercial Vegetable Production Recommendation Guide.  Cooperative Extension Service, University of Delaware, Newark, DE.

Kleczewski, N.M. 2014.   Cover Story-Coming Clean: Why greenhouse sanitation must be a priority.  Produce Grower Magazine.  Published online at http//

Kleczewski, N.M. and D. Egel. 2011. Fungicide resistance management for Indiana Vegetables. Purdue University Factsheet-BP-183-W.

Kleczewski, N.M., and D. Egel. 2011. Greenhouse sanitation for disease management. Purdue University Factsheet-HO-250-W.

Kleczewski, N.M., S.L. Flory, and G. Nice. 2011. An Introduction to Microstegium vimineum Japanese stiltgrass/Nepalese browntop) an Emerging Invasive Grass in the Eastern United States.  Purdue University Factsheet-WS-49-W.

Kleczewski, N.M., P. Bonello, and J. Chatfield. 2009. Pruning and Care of Tree Wounds. Ohio State Factsheet-HYG-3311-09.

Kleczewski, N.M., and D. Lewandowski. 2009.  Virus Diseases of Greenhouse Floral Crops. Ohio State Factsheet-HYG-3065-08.

Kleczewski, N.M, and P. Bonello. 2008. Sudden Oak Death. Ohio State Factsheet-HYG-3309-08.

Kleczewski, N.M., and P. Bonello. 2008. Mycorrhizae in Urban Settings. Ohio State Factsheet-HYG-3305-08.

Kleczewski, N.M., and P. Bonello. 2007. Mycorrhizal inoculations of disturbed soils: What do we know? The Buckeye Arborist 38: 12-14.

Kleczewski, N.M. and P. Bonello. 2007. Mycorrhizal inoculations of disturbed soils: What do we know? The Ohio Woodland Journal 14: 14-15.

Kleczewski, N.M., and P. Bonello. 2007. Feature Article: Commercial inoculation of trees in urban soils:  More questions than answers. The Buckeye, January: 1-8.


Contact Information
Nathan Kleczewski

Extension Field Crops Plant Pathologist
Secondary appointment to faculty

145 Townsend Hall

Newark, DE
Phone: (302) 831-4768