• The Plant Pathology Journal
• /
• v.25 no.3
• /
• pp.294-298
• /
• 2009

Stem canker symptoms were observed in a rape field in Muan, Korea during a disease survey in May 2006. A total of 15 isolates of Phoma sp. were obtained from the infected stems of the plant. All isolates were identified as Leptosphaeria biglobosa based on their morphological and cultural characteristics. The Korean isolates of L. biglobosa were assigned to 'brassicae' among six subclades of L. biglobosa complex based on the entire ITS sequences of rDNA. Pathogenicity of the fungal isolates was confirmed on leaves and stems of rape by artificial inoculation. This is the first report that Leptosphaeria biglobosa causes stem canker of rape in Korea.

• Research in Plant Disease
• /
• v.28 no.3
• /
• pp.132-142
• /
• 2022

Plantation forests are established by planting Eucalyptus tree species to provide timber and pulp for the construction industries and to meet the energy needs in Ethiopia. Besides the extensive Eucalyptus plantations in the country, fungal pathogen-related diseases are the main challenges to successful production and management. The disease survey was conducted in the Eucalyptus growing areas of Ethiopia during 2019/2020 and 2020/2021. The objective of this research was to assess the diseases associated with Eucalyptus plant species and identify the causal fungal species. Plants of E. camaldulensis were the dominant species in the survey fields and were severely associated with stem and branch canker diseases. Diseased samples were collected and fungal species were identified as Didymellaceae according to culture morphology and affirmed by internal transcribed spacer sequence analysis. In phylogeny, isolates in the study and a reference strain formed supportive monophyletic clades with strong 90% and 95% support with Didymella coffeae-arabicae and Didymella pinodella respectively. Pathogenicity tests revealed that Didymellaceae could infect E. camaldulensis. The findings are the first reports of Eucalyptus stem canker disease caused by Didymellaceae in Ethiopia.

• The Plant Pathology Journal
• /
• v.28 no.1
• /
• pp.55-59
• /
• 2012

Northern stem canker caused by $Diaporthe$ $phaseolorum$ var. $caulivora$ ($Dpc$) has become a serious disease in soybean. The objectives of this study were to survey the existence of $Dpc$ on soybean in Korea, and to examine the potential pathogenicity of $Dpc$ in seed decay. One such isolate, SSLP-4, isolated from a field-grown plant of the Korean soybean cultivar Danbaekkong, was identified as $Dpc$, based on its morphological and molecular characteristics by sequences of internal transcribed spacer (ITS), translation elongation factor (TEF) 1-${\alpha}$ and ${\beta}$-tubulin regions, as well as pathogenic analyses. Moreover, morphological and molecular analyses revealed that isolate SSLP-4 was nearly identical to $Dpc$ strains from the United States. Pathogenicity tests on hypocotyls of soybean seedlings and detached leaves resulted in typical symptoms of soybean northern stem canker and inoculation on plants at R5-R7 stage caused seed decay. All results suggest that the $Dpc$ strain SSLP-4 can cause both stem canker and seed decay on soybean. Thus, the SSLP-4 isolate has the potential to contribute greatly to understanding of host plant resistance mechanisms, both at vegetative and reproductive growth stages in soybean.

• The Korean Journal of Mycology
• /
• v.40 no.4
• /
• pp.266-270
• /
• 2012

Stem canker and tuber rot symptoms were observed on yam grown in Andong and Jinju, Korea in 2011. A total of 20 isolates of Rhizoctonia and allied fungi were obtained from the symptomatic plants. Among the isolates, 8 isolates were identified as Rhizoctonia solani and 12 isolates as Ceratobasidium sp. based on rDNA-internal transcribed spacer (ITS) sequence similarity. In the cluster analysis of rDNA-ITS sequences, 7 isolates of R. solani belonged to AG 2-2IIIB and remaining one to AG 1-1A. In addition, among the 12 isolates of Ceratobasidium sp., 7 isolates belonged to AG-Fa, three isolates to AG-A and the other two isolates to AG-Fb and AG-O, respectively. Pathogenicity tests showed that all the R. solani AG 2-2IIIB isolates are pathogenic on stem and tuber of yam but R. solani AG 1-1A and all the Ceratobasidium isolates are non-pathogenic. The results indicate that R. solani AG 2-2IIIB is an important pathogen causing stem canker and tuber rot on yams grown in the study areas. This is the first report of R. solani AG 2-2IIIB causing stem canker and tuber rot of yam in Korea.

• Mycobiology
• /
• v.43 no.3
• /
• pp.366-370
• /
• 2015

Acanthopanax divaricatus, a member of the Araliaceae family, has been used as an invigorant in traditional Korean medicine. During disease monitoring, a stem with small, irregular, brown lesions was sampled at a farm in Cheonan in 2011. The symptoms seen were sunken cankers and reddish-brown needles on the infected twig. The isolated fungal colonies were whitish, having crenated edges and aerial mycelium on the surface, and with black gregarious fruiting bodies. The reverse plate was creamy white. Conidia were $17{\sim}22{\times}3.5{\sim}4.2{\mu}m$, fusiform, 4-septate, and straight to slightly curved. The nucleotide sequence of the partial translation elongation factor 1 alpha gene of the fungal isolate, shares 99% sequence identity with that of known Pestalotiopsis ellipsospora. Based on the results of the morphological and molecular analyses, the fungal isolate was identified as P. ellipsospora. In Korea, this is the first report of canker on A. divaricatus.

• Research in Plant Disease
• /
• v.22 no.4
• /
• pp.217-226
• /
• 2016

Seasonal prevalence of bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) was investigated at a naturally infected orchard in Boseong, Jeonnam in 2014 and 2015. Stem canker began to occur in mid-February in 2014 and early March in 2015. Bacterial ooze was observed on canes, leaders and trunks until late May and gradually disappeared thereafter. The percentages of infected trees were 44.7% and 69.7% in 2014 and 2015, respectively. Trees with trunk canker in a previous year died in 2015. Leaf canker symptoms began to appear as brown spots with chlorotic halos in early May and irregular dark brown spots without halos were observed under humid conditions. Leaf canker progressed until mid-July in 2014 and late July in 2015. No Psa was detected from the leaf lesions on leaves thereafter, but new infection of Psa was observed on leaves in late October. Infected blossoms with blighted calyx were sometimes observed from mid-May. Optimal monitoring period to detect Psa was May when it could be easily detected from stems, leaves and blossoms. Disease cycle of bacterial canker of kiwifruit modified for Korea was proposed based on the seasonal prevalence of bacterial canker analyzed according to weather data in Boseong, Jeonnam over 2 years.

• KSBB Journal
• /
• v.10 no.2
• /
• pp.166-169
• /
• 1995

Spores of Trichoderma harzianum TCC 52445 for control of Rhlzocronia stem canker on potato were immobilized in various natural matrix, and germination rate and some rheological properties of the spore-matrix complex were Investigated. Germination rate of gelatin gel-spore complex and potato starch gel-spore complex were 2.8% and 2.9%, respectively, but hardness and cohesiveness of the gelstin gel-spoke complex were better than those of potato starch-spore complex. The hardness and cohesiveness were increased when the spores were immobilized in hybrid gelatin gel made by mixing several different types of natural matrix, but decreased their germination rate. Addition of corn steep liquor (1%) as spore nutrient in gelatin gel-spore complex was helpful for increasing the germination rate.

• Journal of Forest and Environmental Science
• /
• v.38 no.2
• /
• pp.137-139
• /
• 2022

In 2021, severely infected trees showing distinct symptoms including branch dieback, necrotic lesions on branches, cankers on the shoots, and dark brown discoloration on the stem on Hovenia dulcis were found in the provincial forest of Jeollabuk-do located in Jangsu, South Korea. The causal agent of the pathogen was identified as Botryosphaeria dothidea based on morphology and sequence comparisons. This is the first confirmed report of B. dothidea causing branch dieback and canker on H. dulcis.

• The Plant Pathology Journal
• /
• v.32 no.2
• /
• pp.85-94
• /
• 2016

Studies were conducted to determine the role of 3-methylthioproprionic acid (MTPA) in the pathogenicity of potato stem canker, Rhizoctonia solani, and the concentrations required to inhibit growth of R. solani under laboratory and plant house-based conditions. The experiments were laid out in a completely randomized design with five treatments and five replications. The treatments were 0, 1, 2, 4, and 8 mM concentrations of MTPA. The purified toxin exhibited maximal activity at pH 2.5 and $30^{\circ}C$. MTPA at 1, 2, 4, and 8 mM levels reduced plant height, chlorophyll content, haulm fresh weight, number of stolons, canopy development, and tuber weight of potato plants, as compared to the control. MTPA significantly affected mycelial growth with 8 mM causing the highest infection. The potato seedlings treated with MTPA concentrations of 1.0-8.0 mM induced necrosis of up to 80% of root system area. Cankers were resulted from the injection of potato seedling stems with 8.0 mM MTPA. The results showed the disappearance of cell membrane, rough mitochondrial and cell walls, change of the shape of chloroplasts, and swollen endoplasmic reticulum. Seventy-six (76) hours after toxin treatment, cell contents were completely broken, cytoplasm dissolved, and more chromatin were seen in the nucleus. The results suggested that high levels of the toxin concentration caused cell membrane and cytoplasm fracture. The integrity of cellular structure was destroyed by the phytotoxin. The concentrations of the phytotoxin were significantly correlated with pathogenicity and caused damage to the cell membrane of potato stem base tissue.

• Research in Plant Disease
• /
• v.12 no.2
• /
• pp.65-68
• /
• 2006

The rose is one of the most important commercial cut flowers in the world. Recently stem blight symptoms have often found in hydroponics and soil cultured roses. These symptoms are appeared by four diseases; gray mold caused by Botrytis cinerea, common canker by Coniothyrium fuckelii, anthracnose by Colletotrichum gloeosporioides, and Pythium root rot by Pythium sp. Each symptom and its causal pathogen is described.