The research in my laboratory focuses on the pathology and molecular systematics of fungi associated with Petri disease and Esca or young and old vine decline in wine and processing grapes. A recent three year survey of vineyards in Pennsylvania and New York showed that Phaeomoniella chlamydospora, five species of Phaeoacremonium, and a complex of phialophora-like fungi are frequently associated with declining grapevines. Members of these genera have been implicated in grapevine decline in the major grape growing regions on the West coast of the United States and on other continents such as Europe, Australia, New Zealand, and South Africa.

During our survey, we also determined that Agrobacterium vitis (crown gall) and tomato ringspot virus accounted for the decline of young and old vines in our region. Our research has led us to conclude that current sources of grape nursery stock can be infested with Petri disease fungi, crown gall and virus. We are working to solve some of these problems by (1) studying the molecular systematics and population variation of Phaeomoniella chlamydospora, Phaeoacremonium spp. and phialophora-like fungi; (2) determining the pathogenicity of Phaeoacremonium species, and select phialophora-like fungi; (3) developing SYBR® Green and Taq Man® probes to allow us to rapidly detect Phaeomoniella and Phaeoacremonium, Agrobacterium vitis, and tomato ringspot virus in grape, and (4) developing a model for a clean vine certification program in Pennsylvania.

Overton, Barrie E., Elwin L. Stewart, and Nancy G. Wenner. 2006. Manganese oxidation in Petri disease fungi as a novel taxonomic character. Phytopathologia Mediterranea 45: S131-S134.

Overton, Barrie E., Elwin L. Stewart, Xinshun Qu, Nancy G. Wenner, and Barbara J. Christ. 2004. Qualitative Real-time PCR SYBR ® Green detection of Petri disease fungi. Phytopathologia Mediterranea 43:403-410.

Chamberlain, Holly L, Amy Y. Rossman, Elwin L. Stewart, Tauno Ulvinen and Gary J. Samuels. 2004. The stipitate species of Hypocrea (Hypocreales, Hypocreaceae) including Podostroma . Karstenia 44:1-24.

Stewart, Elwin L. and Nancy G. Wenner. 2004. Grapevine decline in Pennsylvania and New York . Wine East July-August:12-21,51-53.

Stewart, E.L., N.G. Wenner and B.E. Hed. 2003. First report of Phaeomoniella chlamydospora in Vitis vinifera, Vitis labrusca and French American Hybrids in Pennsylvania and New York. Plant Disease 87:750.

Johnson, D.A., E.G. Simmons, J.S. Miller and E.L. Stewart. 2002. Taxonomy and pathology of Macrospora/Nimbya on some North American bulrushes (Scirpus spp.) Mycotaxon 84:413-428.

Chaverri, Priscila, Gary J. Samuels, and Elwin L. Stewart. 2001. Hyopcrea virens sp. nov. the teleomorph of Trichoderma virens. Mycologia 93(6):1113-1124.

Chaverri, Priscila, Gary J. Samuels, Elwin L. Stewart, and Loengrin Umanã. 2001. Hyopcrea nigrovirens , a new species with a gliocladium-like anamorph. Mycologia 93(4):758-763.

Stewart, E.L., J.W. Travis, N.G. Wenner, B.E. Hed, M.L. Chien and A.J. Muza. 2001. Grapevine decline in Pennsylvania and New York: a guide to symptoms and understanding the disease. The Pennsylvania State University, Department of Plant Pathology and Cooperative Extension Service, University Park, PA. 6pp.

Stewart, E.L., Zhaowei Liu, Pedro Crous, and Les J. Szabo. 1999. Phylogenetic relationships among some cercosporoid anamorphs of Mycosphaerella based on rDNA sequence analysis. Mycological Research 103(11):1491-1499.

Etebarian, H. R., R. D. Wilcoxson, E. L. Stewart, and R. P. Woodward. 1996. Isozyme patterns of Fusarium culmorum . Iranian J. of Plant Pathology 32(1-2):9-21.

Kuznia, R. A., R. A. Meronuck, and E. L. Stewart. 1994. Effect of seed treatment on stand establishment root necrosis, and yield of Lupinus albus. Plant Disease 77(9):892-895.

Pfleger, F. L., E. L. Stewart, and R. K. Noyd. 1994. Role of VAM fungi in mine land revegetation. In: Mycorrhizae and Plant Health, pp. 47-81. Eds. F. L. Pfleger and R. G. Linderman. American Phytopathological Society Press, St. Paul, MN .

Fatokun, C. A., D. Danesh, N. D. Young, and E. L. Stewart. 1993. Molecular taxonomic relationships in the genus Vigna based on RFLP analysis. Theoretical and Applied Genetics 86:97-104.