New Zealand Journal of Crop and Horticultural Science abstracts
Etiology of almond shriveled kernel disease
J. K. UYEMOTO1
W. K. ASAI 2
B. C. KIRKPATRICK 1
1USDA-ARS
Department of Plant Pathology
University of California
Davis, CA 95616
United States
email: jkuyemoto@ucdavis.edu
2Cooperative Extension
University of California
Modesto, CA 95355
United States
Abstract In a commercial orchard, mature trees of the almond
(
Prunus dulcis (Mill.) D. Webb) cultivar `Butte' propagated on peach
(
P. persica (L.) Batsch) seedlings exhibited delayed budbreak in spring,
sparse foliage, poor shoot growth, and produced shriveled kernels. Extracts of
leaf petioles from diseased, but not healthy, `Butte' trees were positive by
dot-blot hybridisation assays for the presence of a phytoplasma. In addition,
diseased almond buds were graft-inoculated onto the `Peerless' almond
propagated on `Marianna 2624' plum rootstock and induced brown line and pitting
at the rootstock/cultivar union, a condition associated with peach yellow leaf
roll phytoplasma (PYLR-phytoplasma) infection in this indicator host.
Furthermore, buds of peach infected with PYLR-phytoplasma induced similar
canopy and kernel symptoms when bud-inoculated onto previously healthy trees of
the almond cultivars `Peerless' and `Nonpareil' propagated on peach seedlings.
However, a `Peerless' tree infected with X-disease phytoplasma appeared
unaffected. Ilarvirus and dsRNA analyses of diseased `Butte' trees were
negative. Diseased trees treated with oxytetracycline caused remission of
symptoms. These results indicate that infections by a phytoplasma, specifically
PYLR-phytoplasma, are responsible for kernel shrivel symptoms in almond trees
grown on peach seedlings.
Keywords Prunus dulcis; P. persica;
ELISA; dot-blot hybridisation assays; phytoplasma
H99014
Received 21 April 1999; accepted 17 June 1999
PDF file of entire paper: medium quality (365K); (scanned from paper original: notes about this process)
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