• The Plant Pathology Journal
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• v.24 no.2
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• pp.112-117
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• 2008

Pre-infection behavior of Fusarium circinatum on stems of pine species was investigated with scanning electron microscopy. Two-year-old stems of Pinus densiflora and p. rigida were inoculated with the fungal conidial suspension and subjected to $25^{\circ}C$ for up to 16 hr. Most microconidia germinated 12 hr after inoculation on pine stems. Conidia produced germ tubes from either one or both ends of microconidia. Germ tubes grew over the stem surface and appeared to enter host tissues through natural openings on pine stems. Surface cracks in the cork were entrance sites of germ tubes of F. circinatum. In addition, host cell wall cracks were often found at the tip of germ tubes. The cuticle appeared to be eroded either at the tip of germ tubes or around germlings. Germ tubes also produced appressoria-like structures, exhibiting swollen tips of germ tubes on the stem surface. There seems to be no significant differences in the pre-infection behavior of F. circinatum on stems between the two pine species.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.402-409
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• 2005

This study was undertaken to compare and estimate the severity of pitch canker of individual trees of Pinus rigida and Pinus rigida ${\times}$ P. taeda in two seed orchards in Jeju island, in which the orchards have been damaged by the pitch canker for seven years. Wind-pollinated two-year-old seedlings of P. rigida and P. rigida ${\times}$ P. taeda, in which the seedlings of P. rigida ${\times}$ P. taeda were from seeds of phenotypically selected, uninfected(but untested) trees, were inoculated with the pathogenic fungus, Fusarium circinatum, isolated from P. rigida and P. thunbergii. The virulence of the isolates was also identified. Statistically significant difference was found in 'stem cankers'(SC; ${\chi}^2=7.76$, P=0.05) among 4 plantations of P. rigida ${\times}$ P. taeda of two seed orchards. P. rigida was higher in 'top kill' (TK) and 'branch tip symptoms' (BT) than those of P. rigida ${\times}$ P. taeda. In artificial inoculation tests, mortality of the seedlings from the resistant candidates was 14% higher than that of the seedlings from the susceptible candidates. This result may becaused by unknown pollen trees and/or candidate tree selection based only on phenotype. Two of five fungal isolates, C-6-L(9) and C-6-L(19), showed significantly higher mortality (68% and 60%, respectively) than others, suggesting that these isolates can be used as virulent isolates for a mass artificial inoculation. Resistance candidate seedlings that were selected from this study can be utilized as useful materials for fundamental studies of genetics and biochemistry to breed resistance varieties to pitch canker.

• Research in Plant Disease
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• v.6 no.1
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• pp.36-38
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• 2000

A disease of Kalopanax pictus was found in Taebaec of Kang-won province. Korea, 1998. Typical symptoms were dark green to brown lesions appeared on the leaf and the stem canker. Many spores appeared on the lesions under humid conditions. A Botrytis species was consistently isolated from the infected plants. Conidia were obvoid to ellipsoid, 1-celled, hyaline or pale brown. The conidia were about 6-12${\times}$4-8$\mu\textrm{m}$ under scanning electron microscope, many micro-projections appeared on the surface of conidia. the isolated fungus infected heathy Kalopanax pictus. symptoms in inoculated plants were similar to those of originally diseased plants. The causal agent was identified as Botrytis cinerea. Gray mold of Kalopanax pictus was proposed to name this disease.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.2
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• pp.93-106
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• 2003

Soilborne diseases pose a serious problem for mulberry cultivation during nursery plantation and established gardens, which cause severe loss in revenue generation of mulberry growers as compared to foliar diseases. Various soilborne diseases affect mulberry. Among them, root knot and root rot affect the established plantation resulting in severe loss in leaf yield apart from deterioration in leaf quality, which is a pre-requisite in successful sericulture to get the good quality of cocoons. Besides, stem-canker, cutting rot, collar rot and die-back, affect the initial establishment and survivability of mulberry plantation in nursery. The problem is difficult to handle, due to the complex nature of the diseases and also involvement of various biotic and abiotic factors. This is compounded by the occurrence of disease complex (especially nematode ＋ soilborne pathogenic microbes) in established mulberry gardens, which facilitates quick spread of the disease and enhance the plant mortality, resulting substantial loss in leaf yield. Therefore, prevention and timely control measures need to be taken up to protect the mulberry plants from different soilborne plant pathogens. In this review article, symptomatology, epidemiology, disease cycle and control measures of soilborne diseases of mulberry are discussed.

• Journal of agriculture & life science
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• v.50 no.2
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• pp.25-32
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• 2016

A severe outbreak of gray mold on kenaf (Hibiscus cannabinus L.) was observed on kenaf grown in the research field of Gyeongsangnam-do Agricultural Research and Extension Services, Jinju, Korea in 2014. Gray mold appeared on young plants as gray-brown velvety mold covering stems and leaves. Infections that girdled the stem caused wilting above the infected area and developed a canker. The casual fungus formed grayish brown colonies on potato dextrose agar. The conidia were one celled, mostly ellipsoid or ovoid in shape, colorless or pale brown in color, and 6-18 × 4-10 ㎛ in size. The conidiophores were 15-32 ㎛ in length. These measurements and taxonomic characteristics were most similar to those of Botrytis. DNA sequencing and phylogenetic analysis of the complete internal transcribed spacer rRNA gene region confirmed that the fungal isolates were indeed Borytis cinerea. Koch's postulates were supported by pathogenicity tests conducted on healthy plants. On the basis of mycological characteristics and pathogenicity test on host plants, the fungus was identified as Botrytis cinerea. To the best of our knowledge, this is the first report of a gray mold caused by B. cinerea on kenaf in Korea.

• Journal of Korean Society of Forest Science
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• v.81 no.2
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• pp.191-199
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• 1992

This study was conducted to identify fungi causing canker dieback and melanconis disease of walnut trees (Juglans sinensis Dode) in Korea and clarify the pathogenicity and factors affecting the growth of these fungi. The causal fungi isolated from infected walnut stems and branches obtained from the commercial walnut orchards in Cheonwon, Goesan, Youngdong were identified as Botryosphaeria dothidea (Moug, ex Fries) Casati et de Notaris, Phoniopsis albobestita Fairman, Melanconis juglandis (Ellis et Everhart) Graves and their pathogenicity was confirmed by inoculation test. Temperature range for minimum growth of three fungi was 8 to $35^{\circ}C$ and the optimum temperature for mycelial growth of B. dothidea and P. albobestita ranged from 25 to $30^{\circ}C$, while the optimum temperature for M. juglandis ranged from 20 to $25^{\circ}C$. The optimum pH range for mycelial growth of P. albobestita was 4.0~5.0 and that for B. dothidea and P. juglandis 4.0~8.0. Glucose, sucrose, starch or maltose, as a carbon source, and histidine or potassium nitrate as a nitrogen source were more suitable compounds for growth. of B, dothidea, P. albobestita grew very well on the medium containing alanine and potassium nitrate as a nitrogen source, and utilized well glucose and sucrose as a carbon source. M. juglandis grew well on the medium containing glucose, and sucrose as a carbon source and utilized well potassium nitrate as a nitrogen source. The dieback and twig blight caused by P. albobestita were more severe than those by B. dothidea and M. juglandis at three locations investigated. Incidences of canker and dieback were more frequently observed in aged walnut trees than in young ones.

• Journal of Korean Society of Forest Science
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• v.89 no.4
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• pp.480-487
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• 2000

Repeated measurement of 472 permanent subplots in slash pine (Pinus elliottii Engelm.) plantations were used to develop survival prediction equations for predicting future number of planted slash pine trees. On the average, about 40 percent of the slash pines in the experimental sites had a stem cankers due to fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) incidence. A stand level survival prediction model was developed that incorporated the incidence of fusiform rust and allowed the transition paths of trees from an uninfected stage to an infected stage. Predicted total surviving number of trees is obtained by adding together the predicted number of infected and uninfected trees. The influence of natural hardwood density and site quality on slash pine survivals tended to show a negative effects on future survivals.