• Research in Plant Disease
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• v.15 no.1
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• pp.13-16
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• 2009

In April 2008, cherry (Prunus yedoensis Matsumura) in Jeju exhibited severe disease of branches forming numerous twigs. Five isolates from diseased leaves were identified as Taphrina wiesneri on the basis of biological and genetic characteristics. Twenty one commercial fungicides were tested for control of the disease in vitro. Of the 21 fungicides, triazole compounds (difenoconazole, propiconazole and tebuconazole) showed relatively good antimicrobial activities. Results from the planta bioassays indicated that triazole compounds reduced the witches' broom disease showing control value $25.7{\sim}52.8%$ compared with the nontreated controls.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.109-114
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• 2002

To evaluate the phylogenetic and taxonomic status of the phytoplasmas associated with water dropwort (Oenanthe javanica DC) disease in Korea and Japan, their 16S rDNA was analyzed. DNAs extracted from water dropworts collected in Korea (Kyongnam province) and Japan (Chiba prefecture) affected by witches' broom and yellows were subjected to PCR using phytoplasma-specific primers, which amplified a 1.4-kbp fragment that included the 16S rDNA. Phytoplasmas were characterized by RFLP analysis using AluI, HaeIII, HhaI, KpnI, MseI, and RsaI restriction enzymes and by sequence analysis of the PCR products. The mater dropwort witches'broom (WDWB) and water dropwort yellows (WDY) 16S rDNA sequences were identical and closely related to onion yellows (OY, 99.9% identity), which belong to the aster yellows (AY) 16S-subgroup. However, the KpnI RFLP analyses clearly distinguished the WDY and WDWB phytoplasmas from the OY phytoplasma. The phylogenetic analysis based on 16S rDNA showed that WDWE and WDY phytoplasmas are members of a relatively homogeneous group that evolved from a common ancestor.

• Journal of agriculture & life science
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• v.43 no.3
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• pp.1-6
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• 2009

This study has been carried out to measure the extent of damage for Witches' broom of cherry trees planted as street trees along the 5.16 road around the Halla Mountain. This study is expected to provide effective measures to prevent the infection of witches' broom. Among the cherry trees examined, almost all the trees of 40 years or over were severely infected. Those around 30 years old were infected as well, though they showing medium level of disease symptoms. However, cherry trees of less than 23 years were observed to be healthy without showing any symptoms. Cherry trees spontaneously growing within 30m width of the 5.16 road in the section from Sanchondan to Kyunwolak were less severely infected by Witches' broom (Taphrima waesneri), though there was a difference by tree age.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.73.2-73
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• 2003

Typical whiches broom symptoms caused by phytoplasma were observed in Ash (Fraxinus rhynchophylla Hence) in Korea. The symptoms were showing abnormally small leaves, short internodes, and proliferation of shoots. Fluorescence and electron microscopy of leaf midribs revealed phytoplasma positive DAPI fluorescence and numerous phytoplasma bodies localized in the phloem sieve tubes. Phytoplasma DNA of 1.8 Kb was detected consistently from all symptomatic samples by the amplification of phytoplasma DNA with the phytoplasma specific primer pair Pl/P7. But no phytoplasma DNA was detected in healthy ash seedlings. Based on sequence analyses of an amplified region, this phytoplasma is closely related to Eqilodium phyllody, Mulberry dwarf, and Aster yellows phytoplasmas with the homology of 99.95 ％, 99.79 ％ and 99.78 ％, respectively, This phylogenetic analyses indicate that ash witches broom phytoplasma but is evidently distinct from the ash yellows group 16SrⅦ and should be classified into the Aster yellows group 16SrⅥ.

• Journal of Korean Society of Forest Science
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• v.94 no.2 s.159
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• pp.103-107
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• 2005

Typical phytoplasma whiches' broom symptoms were observed in Ash (Fraxinus rhynchophylla Hence) in Korea. The symptoms of the disease were showing abnormally small leaves, shorted internodes and proliferation of shoots. Examination of fluorescent and electron microscopy of leaf midribs revealed numerous phytoplasma bodies localized in the phloem tube cells. The phytoplasmas were detected in all the symptomatic samples by the amplification with phytoplasma specific primer pair P1/P7 consistently, and the expected size was 1.8 kb. However, the phytoplasma DNA was not detected in healthy seedlings. Based on sequence analysis of amplified region, this phytoplasma has close homologies with eqilodium phyllody, mulberry dwarf, and aster yellow phytoplasmas, 99.95%, 99.79% and 99.78%, respectively, This phylogetic analysis indicates that ash witches' broom phytoplasma should be classified in the aster yellow group 16SrVI and clearly distinct from the ash yellow group 16SrVII.

• The Plant Pathology Journal
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• v.28 no.3
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• pp.239-247
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• 2012

Phytoplasmas have been associated with more than 46 plant species in Korea. Several vegetables, ornamentals, fruit trees and other crop species are affected by phytoplasma diseases. Six 16Sr groups of phytoplasmas have been identified and these phytoplasmas are associated with 63 phytoplasma diseases. Aster yellows phytoplasmas are the most prevalent group and has been associated with more than 25 diseases in Korea. Jujube witches' broom, paulownia witches' broom and mulberry dwarf diseases cause economic losses to host trees throughout the country. So far, Korean phytoplasmas belong to six species of 'Candidatus Phytoplasma'; 'Ca. P. asteris', 'Ca. P. pruni$^*$', 'Ca. P. ziziphi', 'Ca. P. trifolii', 'Ca. P. solani$^*$' and 'Ca. P. castaneae'. The diseases are distributed throughout the country and most of them were observed in Gyeongbuk and Chonbuk provinces. At least four insect vectors; Cyrtopeltis tenuis, Hishimonus sellatus, Macrosteles striifrons and Ophiola flavopicta have been identified for phytoplasma transmission.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.81-88
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• 2011

The anti-phytoplasma activities of surfactin (derived from Iranian native Bacillus subtilis isolates) and tetracycline towards Candidatus "Phytoplasma aurantifolia", the agent of lime Witches' broom disease, were investigated. HPLC was used to quantify the surfactin production in four previously characterized native surfactin-producing strains, and the one producing the highest amount of surfactin (about 1,500 mg/l) was selected and cultivated following optimized production and extraction protocols. Different combinations of purified surfactin and commercial tetracycline were injected into artificially phytoplasmainfected Mexican lime seedlings using a syringe injection system. An absolute quantitative real-time PCR system was developed to monitor the phytoplasma population shifts in the lime phloem during 3 months following the injections. The results revealed that the injections of surfactin or tetracycline had a significant inhibitory effect on Candidatus "P. aurantifolia". However, the combined treatment with both surfactin and tetracycline (1:1) resulted in the highest inhibition due to a synergic effect, which suppressed the phytoplasma population from about $2{\times}10^5$ to less than 10 phytoplasma units/g plant tissue.

• Korean journal of applied entomology
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• v.23 no.4 s.61
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• pp.215-220
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• 1984

Mulberry dwarf, paulownia witches' broom, jujube witches' broom, and sumach witches' broom are known to be associated with mycoplamalike organisms(MLO) in Korea. Simple microscopic detection of MLO infection in these plants was attempted. Periwinkle plant was also tested. Application of $0.2\%\;and\;0.4\%$ solution of Dienes' stain gave diagnoatic value for MLO-induced diseases of periwinkle and mulberry. Among the various plant parts examined, young herbaceous stem just below the apical part gave the best result. Density of staining reaction was proportional to disease severity. Longitudial sections were superior to transverse sections in confirming MLO infection by staining. Light source without blue filter was useful for increasing the color contrast between sieve tube and xylem vessel and for eliminating misinterpretation. Paulownia, jujube, and sumach samples gave no clear difference in staining reaction between healthy and diseased sections even when various modifications of Dienes' staining procedure were tried.

• Korean journal of applied entomology
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• v.4
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• pp.7-10
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• 1965

In an experiment to evaluate the various aspects of symptom of witches' broom of jujube tree with two different kinds of scions, taken from diseased plant and stem- grafted upon sound stocks-one cut before wintering(stored in cellar), the other after wintering, it was observed that the disease rate of those cut before wintering(Nov.) was $\98\%$ whereas those cut after wintering(March) showed much lower rate, $3\%$ initially and gradually increased up to $39\%$. In another experiment of diseased bud grafted into healthy seedling, the finding made in the following year was that 14 stocks(only one of which salt union by callusing) were infected out of the given 23- in the initial stage only 4, yet gradually increased to the number of 14. The shoots from the ground portion of the diseased stock were in general more quickly subjected to the disease than the others. Under natural condition, the diseased trees develop at first seemingly the same leaves as healthy ones; it is not until the branches and loaves grow to a considerable degree that the symptom appears. Once appearing, tile disease grows and the symptom continues to appear as late as in Sept. and early Oct., causing tile plant to develop the extraordinary branches and leaves of extremely reduced size, the typical symptom of witches' broom. Such phenomenon can be observed in the experiments of the foregoing paragraphs. And the suckers and roots of diseased plant are bound to be infected, it was found out with no exception. Viewing from the results of the above experiments and observation, it is believed that the low temperature during winter causes the virus in the above-ground portion of diseased plant to diminish or inactivated, and subsequently the virus in the roots moves up or multiply in the sprouting season.

• Journal of Korean Society of Forest Science
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• v.104 no.2
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• pp.332-335
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• 2015

Taphrina wiesneri, a pathogen of cherry witches' broom, is highly pathogenic to Prunus yedoensis Matsumura which are widely planted in parks and streets in South Korea. In order to control the disease, it is crucial to know the life cycle of the fungus. We attempted to detect the fungus tentatively overwintering in shoots and branches of cherry trees both having witches' broom and healthy before flowering and leafing in spring using PCR with species-specific primer set (TwITSF and TwITSR). Genomic DNAs were extracted from the symptomatic and the asymptomatic shoots or branches. Results indicated that T. wiesneri is present in leaf buds and inner bark not only in symptomatic branches but also in the asymptomatic branches in diseased trees. However, the fungus was not detected in flower buds of the symptomatic trees and any samples of healthy trees.