Antagonistic effects of Epicoccum purpurascens,
Aureobasidium pullulans, Trichoderma spp., and Botrytis
cinerea on establishment of Monilinia fructicola infections
in cherry and peach blossoms were assessed in field and mist
chamber studies. Conidia of each fungus were applied to
blossoms that were subsequently inoculated with conidia of
M fructicola. Mist chamber experiments on forced cherry
blossoms demonstrated that recovery of M. fructicola was
significantly reduced (P=.05) when spores of E. purpurascens
and B.cinerea had been applied 24 hr prior to inoculation
with M. fructicola. Reduction in recovery of M. fructicola
was comparable to that obtained with the fungicide benomyl.
In field trials done in 1990 and 1991, applications of
E. purpurascens and A. pullulans reduced cherry blossom
blight relative to nontreated blossoms by 47 to 65 and 54 to
58%, respectively, compared to reductions of 80 to 96 and 84
to 97% with the fungicides benomyl and iprodione,
respectively. Twig blight in peach, an indicator of blossom
blight infection, was reduced by 37% relative to nontreated
blossoms with applications of E. purpurascens, compared to
54 and 51% reductions with benomyl and iprodione,
respectively.
Analysis of the influence of antagonistic fungi
sprayed onto blossoms on fruit set indicated that B.cinerea
was a weak pathogen of stone fruit blossoms. Significant
reductions (P=.05 and P=.10) were obtained in fruit set
compared with the nontreated control when conidia of B. cinerea
were applied to both cherry and peach blossoms in
1991.
Latent Monilinia infections were evaluated by dipping
green cherries in the herbicide paraquat. Applications of
E. purpurascens and A. pullulans to blossoms caused
reductions in the number of latent Monilinia infections in
green cherries by 18 and 49%, respectively in 1990, and 61
and 66% respectively in 1991. This compares with reductions
of 98 and 92% in 1990 and 1991, respectively, with the
fungicide iprodione. It was observed that the antagonists
E. purpurascens and B. cinerea also became established as
latent infections. These fungi were recovered at a
significantly (P=.05) higher percentage on green cherries
where they had been applied as antagonists to blossoms.
No meaningful differences were detected in the amount
of brown rot that developed on fruit due to the influence of
fungal treatments on blossoms. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37180 |
| Date | 14 January 1992 |
| Creators | Wittig, Hans P. P. |
| Contributors | Johnson, Kenneth B. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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