Wakar Uddin, Ph.D.

  • Professor
Wakar Uddin, Ph.D.
101 Buckhout Lab (office)
106/107 Buckhout Lab (lab)

University Park, PA 16802
Work Phone: 814-777-4498
Fax: 814-863-7217

Areas of Expertise

  • Epidemiology and management of turfgrass diseases
  • Population biology of turfgrass pathogens
  • Host defense response in turfgrass pathosystem
  • Chemical control of turfgrass diseases


  1. B.S., IPM, University of Nevada
  2. M.S., IPM, University of Nevada
  3. Ph.D., Plant Pathology, University of Georgia

Areas of Interest

Epidemiology and management of gray leaf spot of perennial ryegrass turf
Induced resistance in turfgrass system through integration of plant defense activators
Integrated management of turfgrass diseases

Program Interests

The turfgrass industry is a billion dollar business in Pennsylvania. Golf courses, landscapes, athletic fields, business and residential lawns, and sod production all represent significant components of the turf industry. Maintaining high quality turf is one of the top priorities of the turf industry. Diseases such as gray leaf spot, anthracnose basal rot, dollar spot, brown patch, and Pythium foliar blights pose significant challenges for the turfgrass industry in producing and maintaining a high quality turf.

My research program involves management of gray leaf spot of perennial ryegrass turf caused by Magnaporthe oryzae, through applications of the principles of plant disease epidemiology and biology of the pathogen. The epidemiological research focuses on the influence of environmental conditions on development of gray leaf spot under various turfgrass management practices. Research on biology of the pathogen entails characterization of the population structure of M. oryzae in various geographic regions of the United States. Additionally, forecasting the outbreaks of dollar spot epidemic through an innovative approach to detection and quantification of pathogen biomass in root and thatch zone, using procedures in molecular biology, is a component of my research in epidemiology.

A second component of my research program encompasses induced systemic resistance in plants through integration of biological and chemical plant defense activators as part of an integrated management for gray leaf spot and dollar spot diseases.

Fungicidal control of various foliar and root diseases of turfgrass is also a significant part of my research program. I maintain a collaborative research with the fungicide industry for development of a sustainable disease management program as part of an integrated turfgrass disease management strategy.

My outreach program involves disease diagnostic services and management recommendations to the turfgrass industry in Pennsylvania. In addition to the resident courses at Penn State in turfgrass diseases, I also offer two online courses, Diagnosis and Management of Turfgrass Diseases, and Interpretation of Turfgrass Literature, as part of Penn State's World Campus distance education program.

Publications in Refereed Journals 

Aynardi, B., Jimenez Gasco, M. D. M., and Uddin, W. 2019. Effects of isolates of Clarireedia jacksonii and Clarireedia monteithiana on severity of dollar spot in turfgrasses by host type. European J. Plant Pathology. 155:817-829

Pruyne, D. T., Schlossberg, M. J., Uddin, W. 2019.  Perennial ryegrass wear resistance and soil amendment by Ca- And Mg-silicates. Agronomy Agronomy 9:578. doi:10.3390/agronomy9100578

Rahman, A., Uddin, W., and Wenner, N. 2015. Induced systemic resistance responses in perennial ryegrass against Magnaporthe oryzae elicited by semi-purified surfactin lipopeptides and live cells of Bacillus amyloliquefaciens. Molecular Plant Pathology 16(6): 546-558.

Rahman, A., Wallis, C. M. and Uddin, W. 2015. Silicon induced systemic defense responses in perennial ryegrass against infection by Magnaporthe oryzae. Phytopathology 105:748-757.

Rahman, R., Kuldau, G. A., and Uddin, W. 2014. Induction of salicylic acid-mediated defense response in perennial ryegrass against infection by Magnaporthe oryzae. Phytopathology 104:614-623

Li, Y, and Uddin, W. 2013. Effects of Relative Humidity on Infection, Colonization and Conidiation of Magnaporthe orzyae in Gray Leaf Spot Pathosystem. Plant Pathology 63:590-597

Ma, B., and Uddin, W. 2009. Fitness and competitive ability of an azoxystrobin-resistant G143A mutant of Magnaporthe oryzae from perennial ryegrass. Plant Dis. 93:1044-1049.

Nanayakkara, U. N., Uddin, W., and Datnoff, L. E. 2008. Soil silicon amendment:  A component of gray leaf  spot  (Magnaporthe oryzae) management strategy in perennial ryegrass turf in golf courses in the United States.  Canadian J. Plant Pathol 31: 415-426

Ma, B., and Uddin, W., and Olaya, G. 2008. Azoxystrobin Baseline Sensitivity of Magnaporthe oryzae Isolates from Perennial Ryegrass Turf in Golf Courses in the Northeastern United States and Evaluation of the Sensitivity of Non-baseline Isolates from Pennsylvania Golf Courses to Azoxystrobin. Canadian J. Plant Pathol 31:57-64.

Nanayakkara, U. N., Uddin, W., and Datnoff, L. E. 2008. Effects of silicon source and rate on development of gray leaf spot of perennial ryegrass turf. Plant Dis. 92: 870-877

Crouch, J.A., Glasheen, B. M., Uddin, W., Clarke, B. B., and Hillman, B. I. 2008. Patterns of Diversity in Populations of the Turfgrass Pathogen Colletotrichum cereale as Revealed by Transposon Fingerprint Profiles. Crop Sci. 48:1203–1210

Nanayakkara, U.N., Uddin, W., and Datnoff, L.E. 2008. Effects of soil type, source, and rate of silicon application on silicon accumulation in perennial ryegrass turf. Plant and Soil 303:83-94

Tosa, Y., Uddin, W., Viji, G., Kang, S., and Mayama, S. 2007. Comparative genetic analysis of Magnaporthe oryzae isolates causing gray leaf spot of perennial ryegrass turf in the United States and Japan. Plant Dis. 91: (in press)

Uddin, W., Soika, M.D., and McNitt, A. S. 2004. "Effects of timing of ethofumesate on severity of gray leaf spot of perennial ryegrass turf." Plant Dis. 87:1146-1152.

Viji, G., Uddin, W., O'Neill, N. R., Mischke, S., and Saunders, J. A. 2004. Genetic Diversity of Sclerotinia homoeocarpa isolates from turfgrasses from various regions in North America. Plant Dis 88:1269-1276.

Uddin, W., Viji, G., and Vincelli, P. 2003. "Gray leaf spot (blast) of perennial ryegrass turf: an emerging problem for the golf course industry." Plant Dis. 87:880-889.

Uddin, W., Viji, G., Schumann, G. L., and Boyd. S. H. 2003." Detection of Pyricularia grisea causing gray leaf spot of perennial ryegrass turf by a rapid immuno-recognition assay." Plant Dis. 86:772-778.

Viji, G., Uddin, W., and Romaine, C. P. 2003. "Suppression of gray leaf spot of perennial ryegrass turf by Pseudomonas aeruginosa from spent mushroom substrate." Biological Control 26:233-243.

Uddin, W., Serlemitsos, K., and Viji, G. 2003. "A temperature and leaf wetness duration-based model for prediction of gray leaf spot of perennial ryegrass turf." Phytopathology 93: 336-343.

Uddin, W., and Turgeon, A. J. 2002. "Willow Hollow golf course: A scenario involving gray leaf spot disease." J. Nat. Sci. Life Sci. Edu. 31:136-140.

Uddin, W., and Viji, G. 2002. "Biological control of turfgrass diseases." Pages 313-337 in: Biological control of major crop plant diseases. S. S. Gnanamanickam ed. Marcel Dekker Publishers, Inc., New York, N.Y.

Viji, G., and Uddin, W. 2002. "Distribution of mating type alleles and fertility status of Magnaporthe grisea causing gray leaf spot of perennial ryegrass and St. Augustinegrass turf." Plant Dis. 86:827-832.

Uddin, W., Viji, G, and Stowell, L. J. 2003. "First report of gray leaf spot on perennial ryegrass turf in California." Plant Dis. 86:75.

Kang, S., Ayers, J. E., De Wolf, E. D., Geiser, D. M., Kuldau, G., Moorman, G. W., Mullins, E., Uddin, W., Correll, J. C., Deckert, G., Lee, Y-H., Lee, Y-W., Martin, F. N., Subbarao, K. 2002. "The Internet-based fungal pathogen database: A proposed model." Phytopathology 91:232-236.

Landschoot, P. J., Park, B. S., and Uddin, W., 2001. "Nontarget effects of PCNB on putting green turf." Intl. Turfgrass Soc. Res. J. 9: 679-684

Viji, G., Wu, B., Kang, S., Uddin, W., Huff, D. R. 2001."Pyricularia grisea causing gray leaf spot (blast) of perennial ryegrass turf: Population structure and host-specificity." Plant Dis. 85:817-826.

Uddin, W., Soika, M. D., Moorman, F. E., and Viji, G. 1999." A serious outbreak of blast disease (gray leaf spot) of perennial ryegrass in golf course fairways in Pennsylvania." Plant Dis. 83:783.

Uddin, W., Burpee, L. L., Stevenson, K. L. 1999." Influence of temperature, leaf wetness duration, and turfgrass age on development of blast disease (gray leaf spot) of Festuca arundinacea." Pages 136-141 in: Proc. 5th Intl. Conf. Plant Prot. Trop. Symp. Kuala Lumpur, Malaysia.

Uddin, W., Stevenson, K. L., Pardo-Schultheiss, R. A., and Rehner, S. A. 1998. "Pathogenic and molecular characterization of three Phomopsis isolates from peach, plum and Asian pear." Plant Dis. 82:732-737.

Uddin, W., and Stevenson, K. L. 1998. "Seasonal development of Phomopsis shoot blight of peach and effect of selective pruning and shoot debris management on incidence." Plant Dis. 82:565-568.

Uddin, W., Stevenson, K. L., and Pardo-Schultheiss, R. A. 1997. "Pathogenicity of Phomopsis sp. on peach causing shoot blight and evaluation of possible infection courts." Plant Dis. 81:983-989.

Uddin, W., McCarter, S. M., and Gitaitis, R. D. 1996. "First report of bacterial leaf spot on oakleaf hydrangea caused by a pathovar of Xanthomonas campestris." Plant Dis. 80:599.

Uddin, W., and McCarter, S. M. 1996." First report of Rhododendron leaf spot caused by Pseudomonas cichorii." Plant Dis. 80:960.

Smiley, R. W., Ingham, R. E., Uddin, W., and Cook G. H. 1994. "Crop sequences for managing cereal cyst nematode and fungal pathogens of winter wheat." Plant Dis. 78:1142-1149.

Smiley, R. W., Gillespie-Sasse, L-M., Uddin, W., Collins, H. P., and Stoltz, M. A. 1993. "Physiologic leaf spot of winter wheat." Plant Dis. 77:521-527.

Smiley, R. W., Uddin, W., Zwer, P. K., Wysocki, D. J., Ball, D. A., Chastain,T. G., and Rasmussen, P. E. 1993. "Influence of crop management practices on physiologic leaf spot of winter wheat." Plant Dis. 77:803-810.

Smiley, R. W. and Uddin, W. 1993. "Influence of soil temperature on Rhizoctonia root rot (R. solani AG-8 and R. oryzae) of winter wheat. Phytopathology 83:777-785.

Uddin, W., and Knous, T. R. 1991. "Fusarium species associated with crown rot of alfalfa in Nevada." Plant Dis. 75:51-56.

Smiley, R. W., Uddin, W., Ott, S., and Rhinhart, K. E. L. 1990. "Influence of flutolanil and tolclofos-methyl on root and culm diseases of winter wheat." Plant Dis. 74:788-791.