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United States Department of Agriculture

Agricultural Research Service

Related Topics

Timothy L Widmer
Foreign Disease-Weed Science
Research Plant Pathologist

Phone: (301) 619-7338
Fax: (301) 619-2880
Room 140
USDA/ARS/FDWSRU
BLDG 1301
1301 DITTO AVENUE
FORT DETRICK, MD, 21702-5023

Projects
BIOLOGY, PATHOLOGY, AND EPIDEMIOLOGY OF EMERGING OOMYCETE PATHOGENS
Appropriated (D)
  Accession Number: 423057

Publications (Clicking on the reprint icon Reprint Icon will take you to the publication reprint.)
Phytophthora megakarya - (Peer Reviewed Journal)
Widmer, T.L., Hebbar, P.K. 2013. Phytophthora megakarya. Forest Phytophthoras. doi: 10.5399/OSU/fp.3.1.3386.
Screening selected Gulf Coast forest species for susceptibility to Phytophthora ramorum - (Peer Reviewed Journal)
Preuett, J.A., Collins, D.J., Luster, D.G., Widmer, T.L. 2013. Screening selected Gulf Coast forest species for susceptibility to Phytophthora ramorum. Plant Health Progress. PHP 2013-0730-01-RS.
Can Epiphytes reduce disease symptoms caused by Phytophthora ramorum - (Peer Reviewed Journal)
Widmer, T.L., Dodge, S.C. 2013. Can Epiphytes reduce disease symptoms caused by Phytophthora ramorum. Biological Control. 65:135-141.
Root susceptibility and inoculum production from roots of Eastern United States oak species to Phytophthora ramorum - (Peer Reviewed Journal)
Widmer, T.L., Shishkoff, N., Dodge, S.C. 2012. Root susceptibility and inoculum production from roots of Eastern United States oak species to Phytophthora ramorum. Plant Disease. 96:1675-1682.
Survival of Phytophthora kernoviae oospores, sporangia, and mycelium - (Peer Reviewed Journal)
Widmer, T.L. 2011. Survival of Phytophthora kernoviae oospores, sporangia, and mycelium. New Zealand Journal of Forestry Science. 41S:S15-S23.
Field damage to yellow starthistle infected by Synchytrium solstitiale, and greenhouse maintenance and host range of the fungus - (Peer Reviewed Journal)
Eskandari, F., Bruckart, W.L., Widmer, T.L. 2011. Field damage to yellow starthistle infected by Synchytrium solstitiale, and greenhouse maintenance and host range of the fungus. Plant Disease. DOI: 10.1094/PDis-2-11-0139.
Synchytrium solstitiale: reclassification based on the function and role of resting spores - (Peer Reviewed Journal)
Bruckart, W.L., Eskandari, F., Widmer, T.L. 2011. Synchytrium solstitiale: reclassification based on the function and role of resting spores. Mycologia. DOI: 10.3852/10-286.
Whole plant inoculations of Viburnum species and cultivars testing for susceptibility to Phytophthora ramorum - (Peer Reviewed Journal)
Widmer, T.L. 2010. Whole plant inoculations of Viburnum species and cultivars testing for susceptibility to Phytophthora ramorum. Journal of Environmental Horticulture. 28:197-202.
Phytophthora kernoviae oospore maturity, germination, and infection - (Peer Reviewed Journal)
Widmer, T.L. 2010. Phytophthora kernoviae oospore maturity, germination, and infection. Fungal Biology. doi:10.1016/j.funbio.2010.06.001. 114:661-668.
Root susceptibility and inoculum production from roots of eastern oak species to Phytophthora ramorum - (Abstract Only)
Widmer, T.L., Shishkoff, N., Dodge, S.C. 2010. Root susceptibility and inoculum production from roots of eastern oak species to Phytophthora ramorum. Phytopathology. 100/S136.
Differentiating Phytophthora ramorum and P. kernoviae from other species isolated from foliage of rhododendrons Reprint Icon - (Peer Reviewed Journal)
Widmer, T.L. 2010. Differentiating Phytophthora spp. isolated from leaves and stems of rhododendron plants. Plant Health Progress. doi: 10.1094/PHP-2010-0317-01-RS.
Long-term survival of Phytophthora kernoviae oospores - (Proceedings) - (12-Nov-09)
Screening Trichoderma asperellum as a Mycoparasite on Phytophthora ramorum - (Proceedings) - (10-Jun-09)
Susceptibility of sprouted oak acorns to Phytophthora ramorum zoospores - (Abstract Only)
Widmer, T.L., Dodge, S.C. 2009. Susceptibility of sprouted oak acorns to Phytophthora ramorum zoospores. Phytopathology. 99:5205.
Standardizing the Nomenclature for Clonal Lineages of the Sudden Oak Death Pathogen, Phytophthora ramorum - (Peer Reviewed Journal)
Grunwald, N.J., Goss, E.M., Ivors, K., Garbelotto, M., Martin, F.N., Prospero, S., Hansen, E., Bonants, P., Hamelin, R., Chastagner, G., Werres, S., Rizzo, D.M., Abad, G., Beales, P., Bilodeau, G.J., Blomquist, C., Brasier, C., Briere, S., Chandelier, A., Davidson, J.M., Denman, S., Elliott, M., Fichtner, E.J., Frankel, S.J., Goheen, E.M., De Gruyter, H., Heungens, K., James, D., Kanaskie, A., Mcwilliams, M., Moralejo, E., Osterbauer, N.K., Palm, M.E., Parke, J.L., Shamoun, S.F., Shishkoff, N., Tooley, P.W., Vettraino, A., Webber, J., Widmer, T.L. 2009. Standardizing the nomenclature for clonal lineages of the sudden oak death pathogen, Phytophthora ramorum. Phytopathology. 99:792-795.
Recovery Plan for Phytophthora kernoviae Causing Bleeding Trunk Cankers, Leaf Blight and Stem Dieback in Trees and Shrubs - (Government Publication)
Benson, M., Ivors, K., Koch, F., Fichtner, E., Garbelotto, M., Rizzo, D., Tjosvold, S., Hansen, E., Parke, J., Hong, C., Chastagner, G., Jeffers, S., Woodward-Williams, J., Kim, S., Britton, K., Denitto, G., Frankel, S., Micales, J., Grunwald, N.J., Martin, F.N., Shishkoff, N., Smith, K.L., Tooley, P.W., Widmer, T.L., Bulluck, R., Burnett, G., Ferguson, L., Fowler, G., Garrett, L., Jones, J., Magarey, R., Randall-Schadel, B., Cardwell, K., Draper, M., Chand-Goyal, T. 2009. Recovery Plan for Phytophthora kernoviae Causing Bleeding Trunk Cankers, Leaf Blight and Stem Dieback in Trees and Shrubs. Government Publication/Report. Available at: http://www.ars.usda.gov/SP2UserFiles/Place/00000000/opmp/P.%20kernoviae%2081100.pdf
Comparing necrosis of Rhododendron leaf tissue inoculated with Phytophthora ramorum sporangia or zoospores - (Peer Reviewed Journal)
Widmer, T.L. 2008. Comparing necrosis of Rhododendron leaf tissue inoculated with Phytophthora ramorum sporangia or zoospores. Plant Disease. 93:30-35.
Protocol for maintenance of Synchytrium solstitiale, cause of false rust on yellow starthistle, under greenhouse conditions - (Abstract Only)
Eskandari, F., Bruckart, W.L., Widmer, T.L. 2008. Protocol for maintenance of Synchytrium solstitiale, cause of false rust on yellow starthistle, under greenhouse conditions. Phytopathology. 98(6,Supplement)S214-215
Comparing New Zealand and United Kingdom isolates of Phytophthora kernoviae - (Abstract Only)
Widmer, T.L. 2008. Comparing New Zealand and United Kingdom isolates of Phytophthora kernoviae. Phytopathology. 98:S171
Investigating the potential of biological control against Phytophthora ramorum - (Proceedings)
Widmer, T.L. 2008. Investigating the potential of biological control against Phytophthora ramorum. Sudden Oak Death Science Symposium. Frankel, S.J., Kliejunns, J.T. and Palmieri, K. M. (eds). USDA Forest Service Gen. Tech. Rep. PSW-GTR-214, Albany, CA. p. 491
Isolation and identification of mycoparasitic isolates of Trichoderma asperellum with potential for suppression of black pod disease of cacao in Cameroon - (Peer Reviewed Journal)
Tondje, P., Roberts, D.P., Bon, M., Widmer, T.L., Samuels, G.J., Ismaiel, A.A., Begoude, A., Tchana, T., Nyemb-Tshomb, E., Ndoumbe-Nkeng, M., Bateman, D., Fontem, D., Hebbar, K. 2007. Isolation and identification of mycoparasitic isolates of Trichoderma asperellum with potential for suppression of black pod disease of cacao in Cameroon. Biocontrol.
An Ipm Program for the Management of Fungal Leaf Blight Diseases of Carrot in New York - (Peer Reviewed Journal)
Gugino, B.K., Carroll, J.E., Widmer, T.L., Chen, P., Abawi, G.S. 2007. An ipm program for the management of fungal leaf blight diseases of carrot in new york. Plant Disease 91:59-65
Field Evaluation of Carrot Cultivars for Susceptibility to Fungal Leaf Blight Diseases in New York - (Peer Reviewed Journal)
Gugino, B.K., Carroll, J.E., Widmer, T.L., Chen, P., Abawi, G.S. 2007. Field evaluation of carrot cultivars for susceptibility to fungal leaf blight diseases in new york. Crop Protection 26:709-714
Impact of Synchytrium Solstitiale on Yellow Starthistle Seedlings and Mature Plants - (Abstract Only)
Widmer, T.L. 2006. Impact of synchytrium solstitiale on yellow starthistle seedlings and mature plants. Phytopathology 96:S122.
Prospects for Biological Control of Teasels, Dipsacus SPP, in the United States - (Peer Reviewed Journal)
Rector, B.G., Harizanova, V., Sforza, R., Widmer, T.L., Wiedenmann, R.N. 2006. PROSPECTS FOR BIOLOGICAL CONTROL OF TEASELS, DIPSACUS SPP., IN THE UNITED STATES. Biological Control. 1:1-14.
Factors Affecting Infection of Yellow Starthistle (Centaurea Solstitialis) by Synchytrium Solstitiale, Causal Agent of False Rust Disease - (Peer Reviewed Journal)
Widmer, T.L., Guermache, F. 2006. Factors affecting infection of yellow starthistle (centaurea solstitialis) by synchytrium solstitiale, causal agent of false rust disease. Plant Disease. 90:425-428
Cryopreservation of Synchytrium Solstitiale in Planta - (Peer Reviewed Journal)
Widmer, T.L. 2006. Cryopreservation of synchytrium solstitiale in planta. Plant Disease. 90:429-432
Biological Control of Yellow Starthistle: New Prospects for An Old Problem. - (Abstract Only)
Smith, L., Cristofaro, M., Pitcairn, M., Bruckart, W.L., Woods, D., Widmer, T.L., Berner, D.K., Drew, A.E. 2004. Biological control of yellow starthistle: new prospects for an old problem.. Ecological Society of America Proceedings.
Centaurea Solstitialis : Root Extract Inhibition of Plant Pathogenic Fungi - (Proceedings)
Guermache, F., Widmer, T.L. 2004. Centaurea solstitialis : root extract inhibition of plant pathogenic fungi. 12th International Conference on Weed Biology, Dijon, France pp. 427-431. INRA, Dijon, France.
Formulation of Phoma Exigua, Potential Biocontrol Agent Against Centaurea Solstitialis - (Proceedings)
Laurent, N., Gras, S., Quimby Jr, P.C., Widmer, T.L. 2004. Formulation of phoma exigua, potential biocontrol agent against centaurea solstitialis. 12th International Conference on Weed Biology, Dijon, France pp.399-406. INRA, Dijon, France.
Filtrates of Rhizosphere Bacteria Suppressive to Centaurea Solstitialis Seed Germination - (Peer Reviewed Journal)
Widmer, T.L., Guermache, F. 2004. Filtrates of rhizosphere bacteria suppressive to Centaurea solstitialis seed germination. Journal of Plant Diseases and Protection. Special Issue XIX:497-502
Formulation of Sclerotinia Sclerotiorum for Use Against Cirsium Arvense - (Peer Reviewed Journal)
Quimby Jr, P.C., Gras, S., Widmer, T.L., Meikle, W.G., Sands, D. 2004. Formulation of sclerotinia sclerotiorum for use against cirsium arvense. Journal of Plant Diseases and Protection. Special Issue XIX:491-495
Exploration for Plant Pathogens Against Taeniatherum Caput-Medusae (Medusahead) - (Proceedings)
Widmer, T.L., Sforza, R. 2004. Exploration for plant pathogens against taeniatherum caput-medusae (medusahead). XI Symposium on Biological Control of Weeds (eds Cullen, J.M., Briese, D.T., Kriticos, D.J., Londsdale, W.M., Morin, L. and Scott, J.K.) pp. 193-197. CSIRO Entomology, Canberra, Australia.
Molecular Identification of a New Member of the Clover Proliferation Phytoplasma Group (16srvi) Associated with Centaureae Solstitialis Virescence in Italy. - (Peer Reviewed Journal)
Faggioli, F., Pasquini, G., Campobasso, G., Widmer, T.L., Quimby Jr, P.C. 2004. Molecular identification of a new member of the clover proliferation phytoplasma group (16srvi) associated with centaureae solstitialis virescence in italy.. European Journal Of Plant Pathology. 110:353-360
In Vitro Culturing of Yellow Starthistle (Centaurea solstitialis) for Screening Biological Control Agents. - (Peer Reviewed Journal)
Guermache, F., Vidal, K., Widmer, T.L. 2004. In Vitro Culturing of Yellow Starthistle (Centaurea solstitialis) for Screening Biological Control Agents. Biological Control 30:330-335.
Plant Pathology and Biological Control of Invasive Weeds - (Book / Chapter)
BRUCKART, W.L., BERNER, D.K., CAESAR, A.J., WIDMER, T.L. PLANT PATHOLOGY AND BIOLOGICAL CONTROL OF INVASIVE WEEDS. Biological Control of Invasive Plants in the United States. In Plant Pathology and Biological Control of Invasive Weeds. E.M. Combs, J.K. Clark, G.L. Piper, and A.F. Cofrancesco (EDS). Oregon State University Press, Corvallis, OR. 2004.
Synchytrium Solstitiale Sp. Nov. Causing a False Rust on Centaurea Solstitialis in France - (Peer Reviewed Journal)
Widmer, T.L. 2004. Synchytrium solstitiale sp. nov. causing a false rust on centaurea solstitialis in france. Mycologia. 96(2):407-410
The Potential Contribution of Natural Enemies from Mediterranean Europe to the Management of the Invasive Weed Arundo Donax (Graminae:arunidinae) in the Usa - (Proceedings)
Kirk, A.A., Widmer, T.L., Campobasso, G., Carruthers, R.I., Dudley, T. 2003. The potential contribution of natural enemies from Mediterranean Europe to the management of the invasive weed arundo donax (graminae:arunidinae) in the usa. In: Proceedings of the California Invasive Plant Council Symposium, Vol. 7 (ed. Pirosko, C.) pp. 62-68. California Invasive Plant Council, Berkley, CA, USA.
First Report of Fusarium Arthrosporioides on Medusahead (Taeniatherum Caput-Medusae) and Preliminary Tests for Host-Specificity - (Peer Reviewed Journal)
SEIGWART, M., BON, M., WIDMER, T.L., CRESPY, N., SFORZA, R. FIRST REPORT OF FUSARIUM ARTHROSPORIOIDES ON MEDUSAHEAD (TAENIATHERUM CAPUT-MEDUSAE) AND PRELIMINARY TESTS FOR HOST-SPECIFICITY. PLANT PATHOLOGY. 2003.
First Report of Phoma Exigua on Centaurea Solstitialis [asteraceae] in Russia - (Peer Reviewed Journal)
Widmer, T.L., Castlebury, L.A., Rossman, A.Y. 2002. First report of phoma exigua on centaurea solstitialis [asteraceae] in russia. Plant Disease 86:922
Impact of Organic Matter Management on Plant-Parasitic Nematodes, Their Damage to Host Crops and Soil Health - (Peer Reviewed Journal) - (19-Mar-02)
Relationship Between Levels of Cyanide in Sudangrass Hybrids Incorporated into Soil and Suppression of Meloidogyne Hapla - (Peer Reviewed Journal)
Widmer, T.L., Abawi, G.S. 2002. Relationship between levels of cyanide in sudangrass hybrids incorporated into soil and suppression of Meloidogyne hapla. Journal of Nematology. 34:16-22.
Impact of Soil Health Management Practices on Soilborne Pathogens and Root Diseases of Vegetables. - (Review Article)
Widmer, T.L., Abawi, G.S. 2000. Impact of soil health management practices on soilborne pathogens and root diseases of vegetables. Applied Soil Ecology. 15:37-47.
Mechanism of Suppression of Meloidogyne Hapla and Its Damage by a Green Manure of Sudan Grass - (Peer Reviewed Journal)
Widmer, T.L., Abawi, G.S. 2000. Mechanism of suppression of meloidogyne hapla and its damage by a green manure of sudan grass. Plant Disease. 84:562-568.
Last Modified: 10/23/2014