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Christina Cowger

USDA Research Plant Pathologist

Biology, epidemiology, and population genetics of small grain pathogens

Gardner Hall 3409

919.513.7388

Research:

Dr. Cowger investigates the biology, epidemiology, and population genetics of economically important pathogens of small grains, particularly wheat and barley. Her goal is to contribute to profitable and sustainable management practices. Her program interacts closely with breeders, extension personnel, and other pathology and population genetics groups in the eastern U.S. and internationally.

Dr. Cowger has expertise in pathogen adaptation to host resistance; host genotype diversity and its effects on pathogen populations; and epidemiological and disease management implications of pathogen population structure.

Her group conducts research in the laboratory, greenhouse, and at multiple field locations. The lab uses molecular techniques to investigate pathogen virulence, species identity, phylogeny, population structure, and migration. Epidemiological modeling and classical field-plot research are carried out, and breeders’ experimental lines are screened to help select for resistance.

Recent Publications:

  • Cowger, C., Meyers, E., and Whetten, R. 2021.  Sensitivity of the U.S. wheat powdery mildew population to QoI fungicides and determination of the complete Blumeria graminis f. sp. tritici cytochrome b gene.  Phytopathology, https://doi.org/10.1094/PHYTO-04-21-0132-R.
  •  Xue, A. G., Lim, S., Chen, Y., Humphreys, G., Cao, W., Menzies, J., Cowger, C., Li, H., and Serajazari, M.  2021.  Virulence structure of Blumeria graminis f. sp. tritici, the causal agent of wheat powdery mildew, in Ontario in 2018 and 2019.  Can. J. Plant Pathol.  https://doi.org/10.1080/07060661.2021.1915876
  •  Reeves, E., Kerns, J. P., Cowger, C., and Shew, B.  2021.  Pythium spp. associated with root rot and stunting of winter wheat in North Carolina.  Plant Dis. 105:986-996.
  • Cowger, C., Beccari, G., and Dong, Y.  2020. Timing of susceptibility to Fusarium head blight in winter wheat.  Plant Dis. 104:2928-2939.
  • Cowger, C., Smith, J., Boos, D., Bradley, C. A., Ransom, J., and Bergstrom, G. C.  2020.  Managing a destructive, episodic crop disease:  a national survey of wheat and barley growers’ experience with Fusarium head blight.  Plant Dis. 104:634-648.
  • Cowger, C., Ward, T., Nilsson, K., Arellano, C., McCormick, S., and Busman, M.  2020.  Regional and field-specific differences in Fusarium species and mycotoxins associated with blighted North Carolina wheat.  Inter. J. Food Microbiol., doi.org/10.1016/j.ijfoodmicro.2020.108594.
  • Anderson, N. R., Freije, A. N., Bergstrom, G. C., Bradley, C. A., Cowger, C., Faske, T., Hollier, C., Kleczewski, N., Padgett, G. B., Paul, P., Price, T., and Wise, K. A. 2020. Sensitivity of Fusarium graminearum to metconazole and tebuconazole fungicides before and after widespread use in wheat in the United States. Plant Health Prog. 21:85-90.
  • Cowger, C., Arellano, C., Marshall, D., and Fitzgerald, J.  2019.  Managing Fusarium head blight in winter barley with cultivar resistance and fungicide.  Plant Dis. 103:1858-1864.
  • Cowger, C., Ward, B., Brown-Guedira, G., and Brown, J.K.M. 2020.  Role of effector-sensitivity gene interactions and durability of quantitative resistance to Septoria nodorum blotch in eastern U.S. wheat.  Front. Plant Sci. 11:155 https://doi.org/10.3389/fpls.2020.00155
  • Beccari, G., Arellano, C., Covarelli, L., Tini, F., Sulyok, M., and Cowger, C. 2019. Effect of wheat infection timing on Fusarium head blight causal agents and secondary metabolites in grain. Inter. J. Food Microbiol. 290:214-225.
  • Cowger, C., Brown, J.K.M., 2019. Durability of quantitative resistance in crops: greater than we know? Annu. Rev. Phytopathol. 57:253-277.
  • Li, G., Cowger, C., Wang, X., Carver, B., and Xu, X.  2019.  Characterization of Pm65, a new powdery mildew resistance gene on chromosome 2AL of a facultative wheat cultivar.  Theor. Appl. Genet. 132:2625-2632.
  • Li, G., Xu, X., Tan, C., Carver, B., Bai, G., Wang, X., Bonman, M., Wu, Y., Hunger, R., and Cowger, C.  2019.  Identification of powdery mildew resistance loci in wheat by integrating genome-wide association study (GWAS) and linkage mapping.  Crop J. 7:294-306.
  • Mehra, L., Adhikari, U., Ojiambo, P., and Cowger, C.  2019.  Septoria nodorum blotch of wheat:  a disease lesson.  Plant Health Instructor. doi.org/10.1094/PHI-I-2019-0514-01.
  • Meyers, E., Arellano, C., and Cowger, C. 2019. Sensitivity of the U.S. Blumeria graminis f. sp. tritici population to demethylation inhibitor fungicides.  Plant Dis. 103:3108-3116.
  • Richards, J.K., Stukenbrock, E.H., Carpenter, J., Liu, Z., Cowger, C., Faris, J.D., Friesen, T.L., 2019. Local adaptation drives the diversification of effectors in the fungal wheat pathogen Parastagonospora nodorum in the United States. PLOS Genet.15(10):e1008223. https://doi.org/10.1371/journal.pgen.1008223
  • Beccari, G., Arellano, C., Covarelli, L., Tini, F., Sulyok, M., and Cowger, C.  2018.  Effect of wheat infection timing on Fusarium head blight causal agents and secondary metabolites in grain.  Int. J. Food Microbiol. 290:214-225.
  • Ficke, A., Cowger, C., Bergstrom, G., and Brodal, G.  2018.  Understanding yield loss and pathogen biology to improve disease management: Stagonospora nodorum blotch – a case study in wheat.  Plant Dis. 102:696-707.
  • Cowger, C., Mehra, L., Arellano, C., Meyers, E., and Murphy, P.  2018. Virulence differences in Blumeria graminis sp. triticifrom the central and eastern United States.  Phytopathology 108:402-411.
  • Abdelrhim, A., Abd-Alla, H., Abdou, E-S., Ismail, M., and Cowger, C.  2018.  Virulence of Egyptian Blumeria graminis sp. triticipopulation and powdery mildew response of Egyptian wheat cultivars.  Plant Dis. 102:391-397.
  • Lookabaugh, E., Shew, B., and Cowger, C. 2017. Three Pythium species isolated from severely stunted wheat during an outbreak in North Carolina. 2017. Plant Health Prog. 18:169-173.
  • Lukaszewski, A., and Cowger C. 2017. Re-engineering of the Pm21 transfer from Haynaldia villosato bread wheat by induced homoeologous recombination. Crop Sci. 57:1-5.
  • Wiersma, A. T., Pulman, J. A., Brown, L. K., Cowger, C., and Olson, E. L. 2017. Identification of Pm58 from Aegilops tauschii. Theor. Appl. Gen. 6:1123-1133.
  • Mehra, L., Cowger, C., and Ojiambo, P. 2016. A model for predicting onset of Stagonospora nodorum blotch in winter wheat based on pre-planting and weather factors. Phytopathology 107:635-644.
  • Kelly, A., Proctor, R. H., Belzile, F., Chulze, S. N., Clear, R. M., Cowger, C., Elmer, W., Lee, T., Obanor, F., Waalwijik, C., and Ward, T. J. 2016. The geographic distribution and complex evolutionary history of the NX-2 trichothecene chemotype from Fusarium graminearum. Fung. Gen. Bio. 95:39-48.
  • Petersen, S., Lyerly, J. H., Maloney, P. V., Brown-Guedira, G., Cowger, C., Costa, J. M., Dong, Y., and Murphy, J. P. 2016. Mapping of Fusarium head blight quantitative trait loci in winter wheat cultivar NC-Neuse. Crop Sci. 56:1-11.
  • Cowger, C., Weisz, R., Arellano, C., and Murphy, J. P. 2016. Profitability of integrated management of Fusarium head blight in North Carolina. Phytopathology 106:814-823.
  • Ben David, R., Parks, R., Dinoor, A., Kosman, E., Wicker, T., Keller, B., and Cowger, C. 2016. Differentiation among Israeli Blumeria graminis f. sp. tritici isolates originating from wild vs. domesticated Triticum species. Phytopathology 106:861-870.
  • Mehra L. K.Cowger, C., Gross, K., and Ojiambo, P. S. 2016. Predicting pre-planting risk of Stagonospora nodorum blotch in winter wheat using machine learning models. Frontiers in Plant Science 7:390. http://dx.doi.org/10.3389/fpls.2016.00390.
  • Van Sanford, D. A., Clark, A. J., Hershman, D., Brown-Guedira, G. L., Cowger, C., Dong, Y., and Baik, B-K. 2015. Registration of ‘Pembroke 2014’ soft red winter wheat. Journal of Plant Registrations. doi:10.3198/jpr2015.07.0045crc.
  • Cowger, C., Parks, R., and Kosman, E. 2015. Structure and migration in U.S. Blumeria graminis f. sp. tritici populations. Phytopathology 106:295-304.
  • Mehra, L. K., Cowger, C., Weisz, R., and Ojiambo, P. S. 2015. Quantifying the effects of wheat residue on severity of Stagonospora nodorum blotch and yield in winter wheat. Phytopathology 105:1417-1426.

Extension & Outreach:

Publications & Videos: Numerous brochures, bulletins, and posters on disease management co-authored with NCSU professors. Co-authored “Small Grain Disease Management” chapter in NCSU Small Grain Production Guide, revised March 2013.   Featured in the North Carolina Small Grain Growers Association’s video series, including videos on FHBleaf rustpowdery mildew, and SNB.

MediaSoutheast Farm Press in 2015 and 2016

Trainings, Diagnostics, and Consultations: teaches small-grain disease diagnosis, epidemiology and management at trainings for extension agents, both in the field and via distance education. Provides trainings at North Carolina Crop Protection School, Crop Improvement Association, and certified crop advisor (CCA) meetings. Diagnoses small-grain samples from North Carolina, South Carolina, and Virginia at NCSU Plant Disease & Insect Clinic. Consults with growers and their advisors.

Teaching:

Dr. Cowger has lectured in PP755, Plant Disease Resistance: Mechanisms and Applications, and in PP506, Epidemiology and Plant Disease Control.

Education

MS, Botany and Plant Pathology, Crop Science Minor, Oregon State University (1997)
Ph.D, Plant Pathology, thesis research on effects of quantitative resistance on pathogen populations, Oregon State University (2002)