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

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dc.contributor.advisor Johnson, Kenneth B,
dc.creator Falconi, Cesar E.
dc.date.accessioned 2012-10-01T21:19:26Z
dc.date.available 2012-10-01T21:19:26Z
dc.date.copyright 1996-06-14
dc.date.issued 1996-06-14
dc.identifier.uri http://hdl.handle.net/1957/34028
dc.description Graduation date: 1997 en_US
dc.description.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 mycelial growth of B. cinerea and P. expansum in nutrient yeast dextrose agar (pH 4.5 or 7.0) incubated for 8 or 30 days at 24 or 1 C, respectively. These three yeasts also were evaluated for their ability to suppress spore germination of B. cinerea and P. expansum in a gradient of apple juice concentrations and to suppress development of gray and blue mold lesions in inoculated fruits of Golden Delicious apple. Germination of B. cinerea and P. expansum was reduced significantly (P≤0.05) when incubated with the yeast isolates in 100 or 50% apple juice, but not in 0, 1 or 10% apple juice. S. roseus and A. pullulans reduced significantly (P≤0.05) the size of gray mold lesions in wounded fruit stored at 5 C and 24 C by 63 to 72 and 81 to 90%, respectively, when compared to the nontreated control. Size of blue mold lesions in fruit stored at 5 and 24 C also were reduced significantly (P≤0.05) by 66 to 38 and 74 to 63%, respectively, when pre-treated with S. roseus and A. pullulans. In general, fruit rot suppression by some yeasts isolated in this study was similar in magnitude to suppression obtained by Cryptococcus laurentii isolate 87-108, a yeast with commercial potential to suppress postharvest rots of pome fruits. Pretreatment of apple wounds with washed cells of A. pullulans, S. roseus, Rhodotorula sp., resulted in disease suppression, but treatment of wounds with cell-free culture supernatant of these isolates did not affect lesion development. Population size of A. pullulans, S. roseus, and C. laurentii increased in apple wounds incubated at 5 or 24 C for up to 25 days, indicating that they colonized the wound site. Data collected in this study support the hypothesis that yeast isolates antagonize fruit pathogens by competing for nutrients in wounds on fruit surfaces. The isolates of A. pullulans and S. roseus show promise for commercial development. en_US
dc.language.iso en_US en_US
dc.subject.lcsh Botrytis cinerea -- Biological control -- Oregon -- Corvallis en_US
dc.subject.lcsh Apple blue mold -- Biological control -- Oregon -- Corvallis en_US
dc.subject.lcsh Apples -- Postharvest diseases and injuries -- Biological control -- Oregon -- Corvallis en_US
dc.subject.lcsh Yeast fungi -- Oregon -- Corvallis en_US
dc.title Epiphytic yeasts isolated from apple leaves to control of gray and blue mold fruit rots of apple en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Master of Science (M.S.) in Botany and Plant Pathology en_US
dc.degree.level Master's en_US
dc.degree.discipline Science en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Richardson, D.
dc.contributor.committeemember Sugar, D.
dc.description.digitization File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR. en_US
dc.description.peerreview no en_us

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