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Title:Interaction Between Two Root Pathogens and the Epidemiology of Pyrenochaeta Glycines on Soybeans
Author(s):Datnoff, Lawrence Elliott
Department / Program:Plant Pathology
Discipline:Plant Pathology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Plant Pathology
Abstract:The interaction between Fusarium oxysporum and Rhizoctonia solani in causing a root rot of soybeans was studied in the growth chamber and field. Disease incidence and severity tended to be higher and dry weights lower for plants inoculated with F. oxysporum + R. solani in comparison to either F. oxysporum or R. solani alone and the controls. In addition, competition and/or antagonism was apparent because R. solani inocula and root infection were lower in the presence of F. oxysporum than with R. solani alone. An interaction exists between F. oxysporum and R. solani.
Pyrenochaeta leaf blotch of soybeans is caused by Pyrenochaeta glycines Stewart. The development of Pyrenochaeta leaf blotch, its effects on yield and 300-seed weight, and if early-maturing cultivars are more susceptible than late-maturing ones were studied in a 2 x 6 factorial experiment. Main plots were weekly applications of fentin acetate sprays and unsprayed treatments. Six soybean cultivars were subplots. Disease severity, Pyrenochaeta leaf blotch vertical progress and area under the disease progress curve for unsprayed cultivars ranged from 16.4 to 30.5%, 90 to 100% and 653.9 to 1322.5, respectively. Yield and 300-seed weight losses between sprayed and unsprayed plots ranged from 6.6 to 37.1% and 20.1 to 25.%, respectively. The severity of Pyrenochaeta leaf blotch was not affected by maturity group.
Studies were initiated to determine if Neonotonia wightii is an alternative host for Pyrenochaeta glycines and if Dactuliophora glycines is a sclerotial state of P. glycines. Red, circular to irregular lesions typical of Pyrenochaeta leaf blotch developed on all soybean leaves inoculated with either D. glycines or P. glycines but not on the controls. Pycnidia of P. glycines developed from colonies initiated from sclerotia of D. glycines. These cultural and pathogenicity studies demonstrate that N. wightii is an alternative host of P. glycines and D. glycines is a sclerotial state in the life cycle of P. glycines.
Issue Date:1985
Description:104 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
Other Identifier(s):(UMI)AAI8521751
Date Available in IDEALS:2014-12-15
Date Deposited:1985

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