Aerial transmission and strategies for control of Pythium on hydroponically grown cucumbers.

Persistent Link:
http://hdl.handle.net/10150/185247
Title:
Aerial transmission and strategies for control of Pythium on hydroponically grown cucumbers.
Author:
Goldberg, Natalie Pauline.
Issue Date:
1990
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:
Recirculating hydroponic cultural systems facilitate continuous dissemination of introduced plant pathogens. Chemicals are unavailable for the control of diseases in hydroponically-grown vegetables, thus alternate methods of control need to be investigated. An experiment was conducted to test the efficacy of filtration of infested water for the control of root rot of cucumber caused by Pythium aphanidermatum. Germinated cucumber seedlings were transplanted into separate hydroponic tanks. Each tank received water from a common source tank which was (a) recirculated through a 20-μm filter or (b) through a 7-μm filter. Pythium aphanindermatum was introduced into the source tank on two infected plants. Recirculation of infested water was conducted every other day for 5 days at a flow rate of 114 L/min for 30 min. One day after recirculation, 67% of the plants in the tank receiving water passed only through the 20-μm filter were infected and all plants were infected within 3-days. None of the plants in the tank which received water passed through the 7-μm filter were infected until 5-days post-recirculation. A repeat experiment yielded similar results, however there was a delay in the onset of disease expression. The fungus was recovered from the surface (0 mm) and middle (8 mm depth), but not from the inner core (16 mm depth) of the 7-μm filter. It was concluded that the 7-μm filter was effective in removing zoospores from infested water. Since plants in the tank receiving water passed through the 7-μm filter eventually became infected, an alternate source of introduction and spread of the pathogen was investigated. Aerial transmission of Phythium aphanidermatum by shore flies (Scatella stagnalis) was documented for the first time. Shore flies which were thought to feed only on blue-green algae and diatoms, also fed on cucumber roots colonized by the fungus. Ninety-seven percent of the first and second instar larvae, 20% of the pupae/third instar larvae, and 10% of adult flies carried mature oospores in their gut. Oospores excreted by larvae and adults were germinable. Phythium aphanidermatum was transmitted to healthy cucumber plants by naturally infested larvae and adult flies. Adult flies infested with P. aphanidermatum may account for pathogen introduction and spread within commercial greenhouse facilities.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Agriculture.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Plant Pathology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Stranghellini, Michael

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleAerial transmission and strategies for control of Pythium on hydroponically grown cucumbers.en_US
dc.creatorGoldberg, Natalie Pauline.en_US
dc.contributor.authorGoldberg, Natalie Pauline.en_US
dc.date.issued1990en_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.abstractRecirculating hydroponic cultural systems facilitate continuous dissemination of introduced plant pathogens. Chemicals are unavailable for the control of diseases in hydroponically-grown vegetables, thus alternate methods of control need to be investigated. An experiment was conducted to test the efficacy of filtration of infested water for the control of root rot of cucumber caused by Pythium aphanidermatum. Germinated cucumber seedlings were transplanted into separate hydroponic tanks. Each tank received water from a common source tank which was (a) recirculated through a 20-μm filter or (b) through a 7-μm filter. Pythium aphanindermatum was introduced into the source tank on two infected plants. Recirculation of infested water was conducted every other day for 5 days at a flow rate of 114 L/min for 30 min. One day after recirculation, 67% of the plants in the tank receiving water passed only through the 20-μm filter were infected and all plants were infected within 3-days. None of the plants in the tank which received water passed through the 7-μm filter were infected until 5-days post-recirculation. A repeat experiment yielded similar results, however there was a delay in the onset of disease expression. The fungus was recovered from the surface (0 mm) and middle (8 mm depth), but not from the inner core (16 mm depth) of the 7-μm filter. It was concluded that the 7-μm filter was effective in removing zoospores from infested water. Since plants in the tank receiving water passed through the 7-μm filter eventually became infected, an alternate source of introduction and spread of the pathogen was investigated. Aerial transmission of Phythium aphanidermatum by shore flies (Scatella stagnalis) was documented for the first time. Shore flies which were thought to feed only on blue-green algae and diatoms, also fed on cucumber roots colonized by the fungus. Ninety-seven percent of the first and second instar larvae, 20% of the pupae/third instar larvae, and 10% of adult flies carried mature oospores in their gut. Oospores excreted by larvae and adults were germinable. Phythium aphanidermatum was transmitted to healthy cucumber plants by naturally infested larvae and adult flies. Adult flies infested with P. aphanidermatum may account for pathogen introduction and spread within commercial greenhouse facilities.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectAgriculture.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.contributor.advisorStranghellini, Michaelen_US
dc.contributor.committeememberHine, Richarden_US
dc.contributor.committeememberGilbertson, Roberten_US
dc.identifier.proquest9111934en_US
dc.identifier.oclc710296000en_US
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