EFFECTS OF SOIL SOLARIZATION AND ANTAGONISTIC BACTERIA ON MACROPHOMINA PHASEOLINA AND SCLEROTIUM ROLFSII (ARIZONA).

Persistent Link:
http://hdl.handle.net/10150/185793
Title:
EFFECTS OF SOIL SOLARIZATION AND ANTAGONISTIC BACTERIA ON MACROPHOMINA PHASEOLINA AND SCLEROTIUM ROLFSII (ARIZONA).
Author:
MIHAIL, JEANNE DENYSE.
Issue Date:
1983
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
An evaluation was made of soil solarization to control Macrophomina phaseolina and Sclerotium rolfsii under the climatic conditions of the Sonoran Desert region of Arizona. Tarping of moist soil with clear polyethylene in the summer was most effective in raising soil temperatures, while tarping during the fall and spring were less efficient. In one summer trial, the maximum temperatures achieved were 7-8 C higher than control plots at 1, 15, and 30 cm depths. In none of the tests was the application of tarp effective in reducing M. phaseolina populations to non-detectable levels. After a six-week summer solarization treatment, S. rolfsii was controlled at the 15-cm but not the 30-cm depth. During a fall treatment control of S. rolfsii was achieved only at the 1-cm depth. After solarization, seeds of Euphorbia lathyris were planted in solarized and control plots. The incidence of M. phaseolina-associated mortality among seedlings planted in solarized plots was always the same as the control plot with the highest disease incidence. The utility of this technique may be limited by the heat tolerance of the target organisms. Studies of bacterial antagonists were initiated to determine their utility in enhancing pathogen control after the solarization treatment. Screening 43 bacterial isolates showed that seven of Pseudomonas fluorescens and one of Serratia marcescens exhibited some form of antagonism toward M. phaseolina, S. rolfsii and Verticillium dahliae in vitro. Antagonism was manifested as a complete inhibition of fungal development or reduced hyphal development coupled with suppression of sclerotial development. The action of the antagonists was found to be fungitoxic or fungistatic rather than fungicidal. None of the four P. fluorescens isolates tested were effective in preventing M. phaseolina infection of E. lathyris seedlings. The ability of these bacteria to prevent sclerotial formation while still permitting hyphal growth may be a useful technique for studying the two phases of the fungal life cycle separately.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Euphorbia lathyris -- Diseases and pests -- Control -- Sonoran Desert.; Macrophomina phaseolina -- Control -- Sonoran Desert.; Sclerotium rolfsii -- Control -- Sonoran Desert.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Plant Pathology; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleEFFECTS OF SOIL SOLARIZATION AND ANTAGONISTIC BACTERIA ON MACROPHOMINA PHASEOLINA AND SCLEROTIUM ROLFSII (ARIZONA).en_US
dc.creatorMIHAIL, JEANNE DENYSE.en_US
dc.contributor.authorMIHAIL, JEANNE DENYSE.en_US
dc.date.issued1983en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractAn evaluation was made of soil solarization to control Macrophomina phaseolina and Sclerotium rolfsii under the climatic conditions of the Sonoran Desert region of Arizona. Tarping of moist soil with clear polyethylene in the summer was most effective in raising soil temperatures, while tarping during the fall and spring were less efficient. In one summer trial, the maximum temperatures achieved were 7-8 C higher than control plots at 1, 15, and 30 cm depths. In none of the tests was the application of tarp effective in reducing M. phaseolina populations to non-detectable levels. After a six-week summer solarization treatment, S. rolfsii was controlled at the 15-cm but not the 30-cm depth. During a fall treatment control of S. rolfsii was achieved only at the 1-cm depth. After solarization, seeds of Euphorbia lathyris were planted in solarized and control plots. The incidence of M. phaseolina-associated mortality among seedlings planted in solarized plots was always the same as the control plot with the highest disease incidence. The utility of this technique may be limited by the heat tolerance of the target organisms. Studies of bacterial antagonists were initiated to determine their utility in enhancing pathogen control after the solarization treatment. Screening 43 bacterial isolates showed that seven of Pseudomonas fluorescens and one of Serratia marcescens exhibited some form of antagonism toward M. phaseolina, S. rolfsii and Verticillium dahliae in vitro. Antagonism was manifested as a complete inhibition of fungal development or reduced hyphal development coupled with suppression of sclerotial development. The action of the antagonists was found to be fungitoxic or fungistatic rather than fungicidal. None of the four P. fluorescens isolates tested were effective in preventing M. phaseolina infection of E. lathyris seedlings. The ability of these bacteria to prevent sclerotial formation while still permitting hyphal growth may be a useful technique for studying the two phases of the fungal life cycle separately.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectEuphorbia lathyris -- Diseases and pests -- Control -- Sonoran Desert.en_US
dc.subjectMacrophomina phaseolina -- Control -- Sonoran Desert.en_US
dc.subjectSclerotium rolfsii -- Control -- Sonoran Desert.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlant Pathologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.identifier.proquest8313480en_US
dc.identifier.oclc688491316en_US
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