William Turechek, Ph.D
Plant Research Pathologist

U. S. Horticultural Research Laboratory
2001 South Rock Road
Fort Pierce, FL 34945
Telephone: (772) 462-5857
Fax: (772) 462-5986
Email: William.Turechek@ars.usda.gov

Current Research Projects

1. Mapping and characterization of the spatial and temporal distribution of tomato yellow leaf curl virus (TYLCV) in southwestern Florida

2. Studying the epidemiology of insect transmitted viruses in watermelon

3. Developing improved diagnostics and approaches for managing angular leaf spot in California strawberry nursery production 

Projects

Angular leaf spot of strawberry is caused by the bacterium Xanthomonas fragariae. The disease is disseminated primarily through systemically infected nursery stock. This creates problems for nurseries wishing to export plants to Europe because of quarantine restrictions. Currently, field inspections for symptoms are used to certify plants free of X. fragariae, but visual inspection is not useful for detecting plants infected systemically. To detect systemic infections, PCR is the desired tool because of its sensitivity, specificity, and ease of use. In our research, we developed three sets of real-time PCR primers and probes – based on a set of standards PCR primers – and determined optimal reaction conditions for use of these primers (Poster Link #1). Real time detection proved to be both more sensitive and specific than standard PCR. Moreover, the detection of X. fragariae in crown tissue extract was possible with real time PCR but not with standard PCR which is a significant improvement over standard PCR. The information on sensitivity and specificity of the primer sets was used to evaluate the performance of these primers with receiver operating characteristic (ROC) curve analysis under different tolerances for the disease (Poster Link #2). The results of this analysis can be used to provide guidance on threshold selection to manage disease below unacceptable levels. We are also working on optimizing a hot water or heat treatment for killing X. fragariae in systemically infected plants (Poster Link #3), as this technique has been proven to be an effective procedure for killing systemic pathogens in other crops. We have worked with a number of heat treatment protocols in small-scale trials and are attempting to adapt this procedure for use in commercial nurseries.

Selected Publications

1.                  Turechek, W.W., and Madden, L.V. 1999. Spatial Pattern Analysis of Strawberry Leaf Blight in Perennial Production Systems in Ohio. Phytopathology 89:421-433.

2.                  Turechek, W.W., and Madden, L.V. 2000. Analysis of the Association between the Incidence of Two Spatially Aggregated Foliar Diseases of Strawberry. Phytopathology 90:157-170.

3.                  Turechek, W.W., Ellis, M.A., and Madden, L.V. 2001. Sequential Sampling for Incidence of Phomopsis Leaf Blight of Strawberry. Phytopathology 91:336-347.

4.                  Turechek, W. W., Mahaffee, W. F., and Ocamb, C. M. 2001. Development of Management Strategies for Hop Powdery Mildew in the Pacific Northwest. Online. Plant Health Progress doi:10.1094/PHP-2001-0313-01-RS.

5.                  Turechek, W.W., and Madden, L.V. 2001. Effect of Scale on Plant Disease Incidence and Heterogeneity in a Spatial Hierarchy. Ecological Modelling 144:75-93.

6.                  Turechek, W.W., and Madden, L.V. 2003. A Generalized Linear Modeling Approach to Characterizing Disease Incidence in a Spatial Hierarchy. Phytopathology 93:458-466.

7.                  Pethybridge, S.J. and Turechek, W.W. 2003. Analysis of the Association among Three Viruses Infecting Hop (Humulus lupulus) in Australia. Plant Pathology 52:158-167.

8.                  Mahaffee, W.F., Turechek, W.W., and Ocamb, C.M. 2003. Effect of Variable Temperature on the Infection Frequency of Sphaerotheca macularis on Humulus lupulus. Phytopathology 93:1587-1592.

9.                  Turechek, W.W. 2004. Nonparametric Tests in Plant Disease Epidemiology. Phytopathology 94:1018-1021.

10.              Turechek, W.W., and Mahaffee, W.F. 2004. Spatial Pattern of Hop Powdery Mildew in the Pacific Northwest. Phytopathology 94:1116-1128.           

11.              Turechek, W.W., and Köller, W. 2004. Managing Resistance of Venturia inaequalis to the Strobilurin Fungicides. Plant Health Progress doi:10.1094/PHP-2004-0908-01-RS.

12.              Turechek, W.W., and Wilcox, W.F. 2005. Evaluating Predictors of Apple Scab with Receiver Operating Curve Analysis. Phytopathology 95:679-691.

13.              Turechek, W.W., Peres, N., and Werner, N. 2006. Pre- and Post-infection Activity of Pyraclostrobin for Control of Anthracnose Fruit Rot of Strawberry Caused by Colletotrichum acutatum. Plant Disease 90:862-868.

14.              Turechek, W.W. 2006. The Practical Considerations of Scale in Plant Pathology. European Journal of Plant Pathology 115:53-59.

15.              Gent, D.H., Mahaffee, W.F., and Turechek, W.W. 2006. Spatial heterogeneity of the Incidence of Hop Powdery Mildew in Hop Cones. Plant Disease 90:1433-1440.

16.              Gent, D.H., Turechek, W.W., and Mahaffee, W.F. 2007. Sequential Sampling for Estimation and Classification of the Incidence of Hop Powdery Mildew I: Leaf Sampling. Plant Disease 91:1002-1012.

17.              Gent, D.H., Turechek, W.W., and Mahaffee, W.F. 2007. Sequential Sampling for Estimation and Classification of the Incidence of Hop Powdery Mildew II: Cone Sampling. Plant Disease 91:1013-1020.

18.              Dewdney, M.M., Biggs, A.R., and Turechek, W.W. 2007. A Statistical Comparison of the Reliability of the Blossom Blight Forecasts of MARYBLYT and Cougarblight with Receiver Operating Characteristic (ROC) Curve Analysis. Phytopathology 97:1164-1176.

19.              Turechek, W.W., Heidenreich, M.C., Lakso, A.N., and Pritts, M.P. 2007. Photosynthesis and Estimation of Virtual Lesion Size of Strawberry Leaves Infected with Diplocarpon earliana. Canadian Journal of Plant Pathology