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A Real-Time PCR Assay for Early Detection of Eastern Filbert Blight

June 2013 , Volume 97 , Number  6
Pages  813 - 818

Thomas J. Molnar, Emily Walsh, and John M. Capik, Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ 08901; Vidyasagar Sathuvalli, Department of Horticulture, Oregon State University, Corvallis 97331-7304 and Hermiston Agricultural Research and Extension Center, Oregon State University, Hermiston 97838; Shawn A. Mehlenbacher, Department of Horticulture, Oregon State University, Corvallis; Amy Y. Rossman, Systematic Mycology & Microbiology Laboratory, United States Department of Agriculture–Agricultural Research Service, Beltsville, MD 20705; and Ning Zhang, Department of Plant Biology and Pathology and Department of Biochemistry and Microbiology, Rutgers University

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Accepted for publication 11 January 2013.

Eastern filbert blight (EFB) is a devastating disease of European hazelnut, Corylus avellana, which causes economic losses in Oregon, where 99% of the U.S. crop is produced. The causal fungus, Anisogramma anomala, is native to eastern North America, where it is found associated with the American hazelnut (C. americana). Although C. americana is tolerant, EFB causes cankers, branch dieback, and death of C. avellana. Detection and identification of A. anomala is time consuming using conventional methods because the fungus can only be cultured from sporulating perithecia and the disease symptoms and signs only show 12 to 16 months after infection. In this study, a TaqMan real-time polymerase chain reaction (PCR) assay based on a ribosomal DNA internal transcribed spacer was developed for A. anomala. The assay was validated with multiple isolates of A. anomala, closely related species, common environmental microorganisms, and over 100 C. avellana samples. The real-time PCR assay detected as low as 0.12 pg of A. anomala genomic DNA, and positively diagnosed EFB on 82% of asymptomatic plants as early as 15 weeks from infection. The real-time PCR assay is more sensitive and faster than traditional diagnostic methods. It can facilitate hazelnut breeding and disease management by early and accurate diagnosis of EFB.

© 2013 The American Phytopathological Society