Related Topics

Timothy L Widmer
Foreign Disease-weed Science Research
Plant Pathology

Phone: (301) 619-7338
Fax: (301) 619-2880
Room 140

USDA/ARS/FDWSRU
1301 DITTO AVENUE
BLDG 1301
FORT DETRICK , MD 217025023

Projects

Biology, Epidemiology, and Detection of Emerging Plant Pathogenic Oomycetes

	In-House Appropriated (D)
	Accession Number: 432647

Publications (Clicking on the reprint icon

will take you to the publication reprint.)

Recovery of Phytophthora ramorum in plant tissue with mixed infections -

Widmer, T.L., Tooley, P.W., Camp, M.J. 2017. Recovery of Phytophthora ramorum in plant tissue with mixed infections. European Journal of Plant Pathology. doi:10.1007/s10658-017-1260-3.

The effect of salinity on the growth, sporulation and infection of Phytophthora ramorum

Preuett, J.A., Collins, D.J., Luster, D.G., Widmer, T.L. 2016. The effect of salinity on the growth, sporulation and infection of Phytophthora ramorum. Fungal Ecology. 23:123-130.

Bioassay conditions for infection of Pinus radiata seedlings with Phytophthora pinifolia zoospores

Widmer, T.L., Dodge, S.C. 2015. Bioassay conditions for infection of Pinus radiata seedlings with Phytophthora pinifolia zoospores. Plant Disease. 99:1204-1209.

Differences in virulence and sporulation of Phytophthora kernoviae isolates originating from two distinct geographical regions

Widmer, T.L. 2015. Differences in virulence and sporulation of Phytophthora kernoviae isolates originating from two distinct geographical regions. Plant Disease. 99:460-466.

Phytophthora megakarya -

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

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 -

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 -

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 -

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 -

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 -

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 -

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 -

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 -

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

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 -

Screening Trichoderma asperellum as a Mycoparasite on Phytophthora ramorum -

Susceptibility of sprouted oak acorns to Phytophthora ramorum zoospores -

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 -

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 -

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 -

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 -

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 -

Widmer, T.L. 2008. Comparing New Zealand and United Kingdom isolates of Phytophthora kernoviae. Phytopathology. 98:S171

Isolation and identification of mycoparasitic isolates of Trichoderma asperellum with potential for suppression of black pod disease of cacao in Cameroon -

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.

Investigating the potential of biological control against Phytophthora ramorum -

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

AN IPM PROGRAM FOR THE MANAGEMENT OF FUNGAL LEAF BLIGHT DISEASES OF CARROT IN NEW YORK -

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 -

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 -

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 -

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 -

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 -

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. -

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 -

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 -

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.

FORMULATION OF SCLEROTINIA SCLEROTIORUM FOR USE AGAINST CIRSIUM ARVENSE -

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

FILTRATES OF RHIZOSPHERE BACTERIA SUPPRESSIVE TO CENTAUREA SOLSTITIALIS SEED GERMINATION -

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

EXPLORATION FOR PLANT PATHOGENS AGAINST TAENIATHERUM CAPUT-MEDUSAE (MEDUSAHEAD) -

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. -

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. -

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 -

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 -

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 -

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 -

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 -

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 -

RELATIONSHIP BETWEEN LEVELS OF CYANIDE IN SUDANGRASS HYBRIDS INCORPORATED INTO SOIL AND SUPPRESSION OF MELOIDOGYNE HAPLA -

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. -

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 -

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.

ARS News Articles

Good-Guy Fungus to Take on Killer of Oaks and Ornamental Crops

Last Modified: 10/19/2017

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