{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/76172"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/76172","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Quantitative Investigations of Infection and Colonization of Peanut Roots by Cylindrocladium crotalariae","abstract":"Cylindrocladium black rot (CBR) is a destructive root disease of peanut caused by Cylindrocladium crotalariae. New and quantitative approaches were developed to estimate the inoculum potential for this soil-borne pathogen under soil-temperature tank conditions favorable for CBR development. Using cultural plating methods, numerous Q. crotalariae infections (1 to > 1,000 per plant) were observed on asymptomatic root systems of peanut plants, susceptible and resistant to CBR, grown in naturally infested soils at 25 C. Regression-line slope values of log10-log10 plots for microsclerotial inoculum density versus the number of observed root infections per plant and per unit root length [0.98 (R2 =0.94) and 0.99 (R2 = 0.94), respectively] indicated direct proportionality between the respective variables. Efficiency of inoculum for observed infection (percent of germinating microsclerotia that infect roots) estimates were high (near 100%), while efficiency of observed infection for necrosis (percent of infections that develop into necroses) estimates were low (0.27 to 0.28%). Observed infection observed infections per m root per day per rates, I 0 r (the number of microsclerotium per g of soil) were significantly lower (P = 0.001) for CBR-resistant 'Spancross• than for CBR-susceptible 'Florigiant•. The majority of observed infections did not appear to be restricted to outer cortical root tissues. A portion of observea infections near root surfaces resulted in subsequent colonization of the inner cortex and stele of plants for each cultivar. A significantly greater (P = 0.05) number of segments from steles of CBR-susceptible Florigiant taproots were colon~zed by Q. crotalariae than those from CBR-resistant Spancross. Using naturally infested peanut field soils, a dose of 7.4 )-lg NaN3 (sodium azide)/g soil was effective in reducing initial microsclerotial populations by 50%, based upon a highly significant dosage-response curve (R2 = 0.96, P = 0.0001). CBR development was reduced significantly (P = 0.05) for Florigiant plants grown in Q. crotalariae-infested soils treated with 7.5 fl' NaN3/g soil or higher, compared to plants grown in untreated soils. Sublethal doses of NaN3 combined with biological control agents may be useful in the development of integrated CBR control measures.","abstract_html":"Cylindrocladium black rot (CBR) is a destructive root disease of peanut caused by Cylindrocladium crotalariae. New and quantitative approaches were developed to estimate the inoculum potential for this soil-borne pathogen under soil-temperature tank conditions favorable for CBR development. Using cultural plating methods, numerous Q. crotalariae infections (1 to > 1,000 per plant) were observed on asymptomatic root systems of peanut plants, susceptible and resistant to CBR, grown in naturally infested soils at 25 C. Regression-line slope values of log10-log10 plots for microsclerotial inoculum density versus the number of observed root infections per plant and per unit root length [0.98 (R2 =0.94) and 0.99 (R2 = 0.94), respectively] indicated direct proportionality between the respective variables. Efficiency of inoculum for observed infection (percent of germinating microsclerotia that infect roots) estimates were high (near 100%), while efficiency of observed infection for necrosis (percent of infections that develop into necroses) estimates were low (0.27 to 0.28%). Observed infection observed infections per m root per day per rates, I 0 r (the number of microsclerotium per g of soil) were significantly lower (P = 0.001) for CBR-resistant 'Spancross• than for CBR-susceptible 'Florigiant•. The majority of observed infections did not appear to be restricted to outer cortical root tissues. A portion of observea infections near root surfaces resulted in subsequent colonization of the inner cortex and stele of plants for each cultivar. A significantly greater (P = 0.05) number of segments from steles of CBR-susceptible Florigiant taproots were colon~zed by Q. crotalariae than those from CBR-resistant Spancross. Using naturally infested peanut field soils, a dose of 7.4 )-lg NaN3 (sodium azide)/g soil was effective in reducing initial microsclerotial populations by 50%, based upon a highly significant dosage-response curve (R2 = 0.96, P = 0.0001). CBR development was reduced significantly (P = 0.05) for Florigiant plants grown in Q. crotalariae-infested soils treated with 7.5 fl' NaN3/g soil or higher, compared to plants grown in untreated soils. Sublethal doses of NaN3 combined with biological control agents may be useful in the development of integrated CBR control measures.","abstract_has_math":false,"creators":["Tomimatsu, Gail Susan"],"institution":"Virginia Polytechnic Institute and State University","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Plant Pathology","degree_department":"Plant Pathology","school":null,"contributors":[],"advisors":[],"committee_chairs":["Griffin, Gary J."],"committee_members":["Hale, Maynard G.","Powell, N.L.","Porter, Duncan M.","Stipes, R. Jay"],"year":1986,"date_issued":"1986","date_published":"1986","updated_at":"2026-07-22T22:20:37Z","subjects":[],"languages":["en_US"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/76172","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Griffin, Gary J."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Hale, Maynard G.","Powell, N.L.","Porter, Duncan M.","Stipes, R. Jay"]},{"key":"dc:contributor.department","label":"Department","values":["Plant Pathology"]},{"key":"dc:creator","label":"Author","values":["Tomimatsu, Gail Susan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-03-10T18:55:16Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-03-10T18:55:16Z"]},{"key":"dc:date.issued","label":"Date","values":["1986"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Plant Pathology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. 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New and quantitative approaches were developed to estimate the inoculum potential for this soil-borne pathogen under soil-temperature tank conditions favorable for CBR development. Using cultural plating methods, numerous Q. crotalariae infections (1 to > 1,000 per plant) were observed on asymptomatic root systems of peanut plants, susceptible and resistant to CBR, grown in naturally infested soils at 25 C. Regression-line slope values of log10-log10 plots for microsclerotial inoculum density versus the number of observed root infections per plant and per unit root length [0.98 (R2 =0.94) and 0.99 (R2 = 0.94), respectively] indicated direct proportionality between the respective variables. Efficiency of inoculum for observed infection (percent of germinating microsclerotia that infect roots) estimates were high (near 100%), while efficiency of observed infection for necrosis (percent of infections that develop into necroses) estimates were low (0.27 to 0.28%). Observed infection observed infections per m root per day per rates, I 0 r (the number of microsclerotium per g of soil) were significantly lower (P = 0.001) for CBR-resistant 'Spancross• than for CBR-susceptible 'Florigiant•. The majority of observed infections did not appear to be restricted to outer cortical root tissues. A portion of observea infections near root surfaces resulted in subsequent colonization of the inner cortex and stele of plants for each cultivar. A significantly greater (P = 0.05) number of segments from steles of CBR-susceptible Florigiant taproots were colon~zed by Q. crotalariae than those from CBR-resistant Spancross. Using naturally infested peanut field soils, a dose of 7.4 )-lg NaN3 (sodium azide)/g soil was effective in reducing initial microsclerotial populations by 50%, based upon a highly significant dosage-response curve (R2 = 0.96, P = 0.0001). CBR development was reduced significantly (P = 0.05) for Florigiant plants grown in Q. crotalariae-infested soils treated with 7.5 fl' NaN3/g soil or higher, compared to plants grown in untreated soils. Sublethal doses of NaN3 combined with biological control agents may be useful in the development of integrated CBR control measures."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Quantitative Investigations of Infection and Colonization of Peanut Roots by Cylindrocladium crotalariae"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Griffin, Gary J."],"dc:contributor.committeemember":["Hale, Maynard G.","Powell, N.L.","Porter, Duncan M.","Stipes, R. Jay"],"dc:contributor.department":["Plant Pathology"],"dc:creator":["Tomimatsu, Gail Susan"],"dc:date.accessioned":["2017-03-10T18:55:16Z"],"dc:date.available":["2017-03-10T18:55:16Z"],"dc:date.issued":["1986"],"dc:description.abstract":["Cylindrocladium black rot (CBR) is a destructive root disease of peanut caused by Cylindrocladium crotalariae. New and quantitative approaches were developed to estimate the inoculum potential for this soil-borne pathogen under soil-temperature tank conditions favorable for CBR development. Using cultural plating methods, numerous Q. crotalariae infections (1 to > 1,000 per plant) were observed on asymptomatic root systems of peanut plants, susceptible and resistant to CBR, grown in naturally infested soils at 25 C. Regression-line slope values of log10-log10 plots for microsclerotial inoculum density versus the number of observed root infections per plant and per unit root length [0.98 (R2 =0.94) and 0.99 (R2 = 0.94), respectively] indicated direct proportionality between the respective variables. Efficiency of inoculum for observed infection (percent of germinating microsclerotia that infect roots) estimates were high (near 100%), while efficiency of observed infection for necrosis (percent of infections that develop into necroses) estimates were low (0.27 to 0.28%). Observed infection observed infections per m root per day per rates, I 0 r (the number of microsclerotium per g of soil) were significantly lower (P = 0.001) for CBR-resistant 'Spancross• than for CBR-susceptible 'Florigiant•. The majority of observed infections did not appear to be restricted to outer cortical root tissues. A portion of observea infections near root surfaces resulted in subsequent colonization of the inner cortex and stele of plants for each cultivar. A significantly greater (P = 0.05) number of segments from steles of CBR-susceptible Florigiant taproots were colon~zed by Q. crotalariae than those from CBR-resistant Spancross. Using naturally infested peanut field soils, a dose of 7.4 )-lg NaN3 (sodium azide)/g soil was effective in reducing initial microsclerotial populations by 50%, based upon a highly significant dosage-response curve (R2 = 0.96, P = 0.0001). CBR development was reduced significantly (P = 0.05) for Florigiant plants grown in Q. crotalariae-infested soils treated with 7.5 fl' NaN3/g soil or higher, compared to plants grown in untreated soils. Sublethal doses of NaN3 combined with biological control agents may be useful in the development of integrated CBR control measures."],"dc:description.degree":["Ph. D."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10919/76172"],"dc:language.iso":["en_US"],"dc:publisher":["Virginia Polytechnic Institute and State University"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Quantitative Investigations of Infection and Colonization of Peanut Roots by Cylindrocladium crotalariae"],"dc:type":["Dissertation"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Plant Pathology"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:20:37Z"}