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Filtering by: Creator Johnson, T. M. Remove constraint Creator: Johnson, T. M. Academic Affiliation Botany and Plant Pathology Remove constraint Academic Affiliation: Botany and Plant Pathology

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  • Diagnosis and Etiology of a Soilborne Disease Complex of Winter Squash (Cucurbita maxima) in the Willamette Valley, OR

    Creator:
    Rivedal, Hannah M.
    Abstract:
    Winter squash (Cucurbita maxima) grown in Oregon’s Willamette Valley for edible seed, frozen foods, and fresh markets is susceptible to an undiagnosed soilborne disease. Diseased squash fields exhibit symptoms of stunting, root and crown rot, vascular discoloration, and late-season wilt, which in extreme cases can lead to total crop failure....
    Resource Type:
    Dissertation
    Full Text:
    Hannah M. Rivedal Alexandra G. Stone Paul M. Severns Kenneth B. Johnson Phytobiomes 3340

  • Effect of resident epiphytic fungi development of brown rot blossom blight of stone fruits

    Creator:
    Wittig, Hans P. P.
    Abstract:
    Antagonistic effects of Epicoccum purpurascens, Aureobasidium pullulans, Trichoderma spp., and Botrytis cinerea on establishment of Monilinia fructicola infections in cherry and peach blossoms were assessed in field and mist chamber studies. Conidia of each fungus were applied to blossoms that were subsequently inoculated with conidia of M fructicola. Mist chamber...
    Resource Type:
    Masters Thesis
    Full Text:
    . Johnson Abstract approved: Antagonistic effects of Epicoccum purpurascens, Aureobasidium pullulans

  • Systematics of the genus Torrubiella

    Creator:
    Johnson, Desiree M.
    Abstract:
    Torrubiella is a genus of entomopathogenic fungi in the Clavicipitaceae (Ascomycota). Species of the genus produce superficial perithecia on a loose mat of hyphae that forms directly on the host. The genus is estimated to contain about 70 species. Torrubiella is hypothesized to be a close relative of Cordyceps because...
    Resource Type:
    Masters Thesis
    Full Text:
    M. Johnson for the degree of Master of Science in Botany and Plant Pathology presented on March 20

  • Contracting nucleolar vacuoles in somatic tobacco cells growing in microcultures

    Creator:
    Johnson, John Morris
    Abstract:
    Contracting nucleolar vacuoles are a general and consistent feature of somatic tobacco cells growing in microcultures. Nucleolar vacuoles were studied in cells from callus tissues of two single-cell clones, H-196 and H-239, of hybrid tobacco (Nicotiana tabacum X N. glutinosa). Vacuoles periodically contracted either completely or incompletely, apparently releasing a...
    Resource Type:
    Dissertation
    Full Text:
    helpful suggestions, Mr. and Mrs. Carl T. Johnson, his parents, for their encouragement, Mrs

  • Genetic variability in the eastern filbert blight pathosystem

    Creator:
    Osterbauer, Nancy K.
    Abstract:
    The heritability of resistance to eastern filbert blight, caused by Anisogramma anomala, in European hazelnut (Corylus avellana) was evaluated in the progeny of seven cultivars crossed in 12 combinations. Progeny produced by crossing 'VR6-28' with three susceptible cultivars segregated 1:1 for complete resistance to eastern filbert blight. Histograms of disease...
    Resource Type:
    Dissertation
    Full Text:
    were provided by Dr. Johnson. T. L. Sawyer maintained plant material in the greenhouse and field

  • Evaluation of kasugamycin-use strategies designed to delay development of resistance in Erwinia amylovora

    Creator:
    Hubbard, Andrew Robert
    Abstract:
    The antibiotics, streptomycin sulfate and oxytetracycline, are used widely for fire blight suppression in the Pacific Northwest region of the United States. The efficacy of streptomycin, however, is compromised by widespread streptomycin-resistance in E. amylovora populations, and oxytetracycline is only partially effective. Consequently, for several years, the aminoglycoside antibiotic, kasugamycin...
    Resource Type:
    Masters Thesis
    Full Text:
    approved: ______________________________________________________ Kenneth B. Johnson The

  • Epiphytic yeasts isolated from apple leaves to control of gray and blue mold fruit rots of apple

    Creator:
    Falconi, Cesar E.
    Abstract:
    Eight phylloplane yeasts were isolated from backyard apple trees in Corvallis, OR. Yeast isolates were classified to genus or species level. All isolates were tested in vitro for antagonistic activity against the postharvest pathogens Botrytis cinerea and Penicillium expansum. Of these isolates, Aureobasidium pullulans, Sporobolomyces roseus Rhodotorula sp., consistently reduced...
    Resource Type:
    Masters Thesis
    Full Text:
    . Johnson, major professor, for his guidance and advice throughout this research. I would like to thank

  • Assessment of potato tuber blight caused by Phytophthora infestans

    Creator:
    Glass, Jenny Rebecca
    Abstract:
    Late blight, caused by Phytophthora infestans, is a devastating problem to potato production in many parts of the world. While the foliar phases of this disease are well characterized, tuber infection, leading to quality losses and disease perpetuation, is less well understood. Experiments were conducted during 1998 and 1999 in...
    Resource Type:
    Masters Thesis
    Full Text:
    Redacted for privacy Redacted for privacy ACKNOWLEDGMENTS I thank Kenneth B. Johnson, Teresa Sawyer

  • Modification of phyllosphere environments to enhance establishment of Gliocladium roseum, an antagonist of Botrytis cinerea

    Creator:
    Bennett, Robert J. (Robert Joe), 1953-
    Abstract:
    Radial colony growth of three isolates of Gliocladium roseum and three isolates of Bottytis cinerea were measured on 1/4 strength potato dextrose agar amended with concentrations of NaHCO₃ ranging from 0-2% (w/v). Compared to the control, reductions in colony diameter of the B. cinerea isolates ranged from 60-79% and 73-89%...
    Resource Type:
    Masters Thesis
    Full Text:
    Bottytis cin ea. Abstract approved : . Johnson Radial colony growth of three isolates of Gliocladium

  • Role of inoculum sources of Botrytis cinerea in the epidemiology of gray mold of snap beans

    Creator:
    Johnson, Kenneth Bjorn
    Abstract:
    Spore dispersal gradients and pod disease gradients from point inoculum sources of Botrytis cinerea were measured over time in two snap bean field experiments. Laboratory grown inoculum was placed at ground level in a 30 x 30 cm square at bloom initiation and removed at full bloom. Dispersal of inoculum,...
    Resource Type:
    Masters Thesis
    Full Text:
    Cynthia Flack for Kenneth Bjorn Johnson ACKNOWLEDGEMENTS I wish to express my gratitude to Dr. M. L