Paul D. Esker
Assistant Professor of Plant Pathology
& Extension Field Crops Plant Pathology
Ph.D.: Iowa State University in
Plant Pathology and Statistics

Research Program:

Our research group is focused on increasing our understanding of how plant diseases affect field crops, including corn, soybean, wheat, and alfalfa.  We are especially interested in determine the risk factors that may reduce yield, and we take combine principles of epidemiology and disease management to understand if and when a disease epidemic may occur.  Specific interests in our laboratory include the role of decision theory and its application for field crop disease management, how different cropping systems affect plant disease dynamics (including the question of scale), how chemical and biological management tactics may reduce the risk of field crop diseases, and methods to improve diagnosis of field crop diseases.  Our laboratory also has an extensive international collaboration, with projects currently in Brazil (soybean), Mexico (corn), and Australia (pyrethrum).

Furthermore, I also am the Field Crops Extension Plant Pathologist.  Primarily, our Extension goals include the integration of current research results into sound management recommendations for Wisconsin’s producers through a variety of multimedia approaches, developing training programs for field crop disease diagnosis, and increasing our understanding the cost-benefit of using different management tactics for field crop disease control.

Current Lab Members:

1. Jennifer Jirak, MS Student in Plant Pathology

Selected Publications:

1. Pethybridge, S. J., F. Hay, P. Esker, T. Groom, C. Wilson, and F. W. Nutter, Jr. Visual and radiometric assessments for yield losses caused by ray blight in pyrethrum. Crop Science  (Accepted for publication pending revision, Feb. 2007).
2. Xu, Z., M. L. Gleason, D. S. Mueller, C. A. Bradley, J. W. Buck, D. M. Benson, P. D. Esker, P. M. Dixon, and J. E. B. A. Monteiro.  Overwintering of Sclerotium rolfsii and Sclerotium rolfsii var. delphinii in North Dakota, Iowa, North Carolina, and Georgia. (Accepted pending revision Aug. 2007).
3. Pethybridge, S. J., F. Hay, P. Esker, C. Wilson, and F. W. Nutter, Jr. 2007. Use of a multispectral radiometer for non-invasive assessments of foliar disease caused by ray blight in pyrethrum. Plant Disease (In Press).
4. Esker, P. D., K. S. Gibb, P. M. Dixon, and F. W. Nutter, Jr. 2007. An application of space-time analysis to improve the epidemiological understanding of the papaya-papaya yellow crinkle pathosystem. Online. Plant Health Progress. doi: 10.1094/PHP-2007-0726-02-RS.
5. Pethybridge, S. J., P. D. Esker, P. Dixon, F. S. Hay, T. Groom, C. R. Wilson, and F. W. Nutter, Jr. 2007. Quantifying loss caused by ray blight disease in Tasmanian pyrethrum fields. Plant Disease 91: 1116-1121.
6. Esker, P. D., J. Harri, P. M. Dixon, and F. W. Nutter, Jr. 2006. Comparison of models for forecasting of Stewart’s disease of corn in Iowa. Plant Disease 90:1353-1357.
7. Nutter, F. W., Jr., P. D. Esker, and R. A. Coelho Netto. 2006. Disease assessment concepts in Plant Pathology. European Journal of Plant Pathology 115:95-103.
8. Nutter, F. W., Jr., and P. D. Esker. 2006. The role of psychophysics in phytopathology. European Journal of Plant Pathology 114: 199-213.
9. Menelas, B., C. C. Block, P. D. Esker, and F. W. Nutter, Jr. 2006. Quantifying the feeding periods required by corn flea beetles to acquire and transmit Pantoea stewartii subsp. stewartii. Plant Disease 90: 319-324.
10. Esker, P. D., K. S. Gibb, A. Padovan, P. M. Dixon, and F. W. Nutter, Jr. 2006. Use of survival analysis to determine the postincubation time-to-death of papaya due to yellow crinkle disease in Australia. Plant Disease 90: 102-107.
11. Pethybridge, S. J., P. D. Esker, F. Hay, C. Wilson, and F. W. Nutter, Jr. 2005. Spatiotemporal description of epidemics caused by Phoma ligulicola in Tasmanian pyrethrum fields. Phytopathology 95: 648-658.
12. Cook, K. A., R. A. Weinzierl, J. K. Pataky, P. D. Esker, and F. W. Nutter, Jr. 2005. Seasonal fluctuations in population densities of the corn flea beetle, Chaetocnema pulicaria (Melsheimer) (Coleoptera: Chrysomelidae) and the impact on the incidence of Stewart’s wilt in corn. J. Econ. Entomol. 98: 673-682.
13. Esker, P. D., J. Obrycki, and F. W. Nutter, Jr. 2004. Trap height and orientation of yellow sticky traps affect capture of Chaetocnema pulicaria (Coleoptera: Chrysomelidae). J. Econ. Entomol. 97: 145-149.
14. Esker, P. D. and F. W. Nutter, Jr. 2003. The temporal dynamics of corn flea beetle populations infested with Pantoea stewartii, the causal agent of Stewart's disease of corn. Phytopathology 93: 210-218.

15. Nutter, F. W., Jr., R. R. Rubsam, S. E. Taylor, J. A. Harri, and P. D. Esker. 2002. Use of geospatially-referenced disease and weather data to improve site-specific forecasts for Stewart’s disease of corn in the U.S. corn belt. Computers and Electronics in Agriculture 37(1-3): 7-14.

16. Esker, P.D., J. Obrycki, and F. W. Nutter, Jr. 2002. Temporal distribution of Chaetocnema pulicaria (Coleoptera: Chrysomelidae) populations in Iowa. J. Econ. Entomol. 95(4): 739-747.

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