• Journal of Korean Society of Forest Science
• /
• v.28 no.1
• /
• pp.97-100
• /
• 1975

Korean white pine (Pinus koraiensis Sieb. & Zucc.), native to Korea and currently the most important timber species in Korea is being threatened by a blister rust discase caused by a Cronartium species. The fungus has been tentatively identified as Cronartium ribicola Fischer. The fungus alternates between P. koraiensis and Pedicularis resupinata L. (a herbaceous perennial) under natural conditions in Korea although experimentally it has been shown to infect several Ribes species. The taxonomic diagnosis of the causal fungus is not fully resolved. A review of the status of this rust disease on P. koraiensis and other possible hosts in Korea and its potential international significance along with present work underway in Korea is discussed.

• Research in Plant Disease
• /
• v.13 no.3
• /
• pp.220-222
• /
• 2007

Rust disease on Korean Azalea (Rododendron yedoense) was occurred in Jeonju, Jeonbuk province of Korea. The typical symtoms of the disease appeared first as small yellowish spots on leaves. Uredinia were observed at hypophyllous of the leaves, yellow or dark yellow in color and globoid in shape with the size of $0.27{\sim}0.46{\times}0.31{\sim}0.61$ mm. Urediniospores were also observed in the leaves, yellow in color with globoid or ovoid in shape with the size of $17.1{\sim}29.2{\times}12.8{\sim}18.2{\mu}m$. Surface characterization of the spores revealed that these spores have papilla-like projections, which were made of $2{\sim}3$ annulation (SA; small annulate). Based on these morphological characterizations the causative fungus was identified as Chrysomyxa rhododendri.

• Journal of Korean Society of Forest Science
• /
• v.37 no.1
• /
• pp.61-63
• /
• 1978

Both bark and wood sections obtained, by cutting with a razor blade, from living tissue of Cronartium ribicola cankers of Korean white pine (Pinus koraiensis) were transferred to a mixture of 2 parts of chloroform and 1 part of methanol, and the sections were stained using a modified lactophenol cotton blue. The formula for this staining is as follows: Lactic acid 20gm, phenol crystal 20gm, cotton blue 0.05gm, and 60% EtOH 100ml. The rust hyphae and haustoria were stained blue, and the wide hyphae with straight or curved haustoria could be distingwished from the pine tissue.

• Corrosion Science and Technology
• /
• v.11 no.2
• /
• pp.48-55
• /
• 2012

Clamping force of a high strength bolt is reduced by a certain period of time after the initial set-up. In case of special treatments on faying surfaces such as protective coating, clamping force is relaxed more severely. Tests for slip critical joints subject to various faying surface parameters were conducted. Five different surface treatments were tested including mill scale surface, blast surface, rust surface and coated surfaces. Each specimen was composed of F10T M20 of high strength bolts and steel plates. Based on the result of slip coefficient test, blast treatment surface showed 0.59, rust treatment surface showed 0.54 and inorganic zinc treatment surface exhibited 0.44. Clean mill treatment surface and red lead paint treatment surface were 0.23, 0.21 respectively. It is identified that the slip coefficient in Korean structural design guide should be determined for various surface conditions. Subsequently from long term relaxation test of ASTM A 490 high strength bolts, relaxation of no-coated surfaces such as blast, clean mill, rust treatment, the loss of initial clamping load was 10.5%, 13.6% and 7.9% for 1,000 hours, while the loss of initial clamping force was reached as 15.0%, 18.7% more than the required redundancy 10% in case of inorganic zinc and red lead painted treatment. It is required that the limit of relaxation on coated faying surface should be established separately for various surfaces.

• The Korean Journal of Mycology
• /
• v.49 no.1
• /
• pp.119-125
• /
• 2021

Hydrangea petiolaris, belonging to the family Hydrangeaceae, is a vine plant distributed in Ulleung, Jeju, and other southern islands of Korea. In October 2017, a rust fungus was discovered on H. petiolaris in Jeju Island, Korea. To identify the rust fungus, we performed a morphological examination and molecular phylogenetic analysis of the internal transcribed spacer and 28S large subunit rDNA sequences. As a result, the fungus was identified as Pucciniastrum hydrangeae-petiolaris, consistent with previous reports from Japan and Russia, but showed a significant phylogenetic distance from Pucciniastrum hydrangeae reported on Hydrangeae spp. in North America. This is the first record of P. hydrangeae-petiolaris on H. petiolaris in Korea.

• The Korean Journal of Mycology
• /
• v.49 no.4
• /
• pp.531-537
• /
• 2021

Styrax japonicus is a deciduous shrub or a small tree belonging to the family Styracaceae. Since 1990, a rust fungus has continuously been found on S. japonicus leaves across the country. The morphological characteristics of the rust fungus were most consistent with those of Pucciniastrum styracinum reported on Styrax obassia in Japan. The species identification was confirmed by molecular phylogenetic analysis of the internal transcribed spacer and large subunit rDNA sequences. The current study provides mycological information with morphological measurements and molecular phylogenetic data of P. styracinum found on S. japonicus in Korea. Therefore, this is the first confirmed report on the presence of P. styracinum on S. japonicus in Korea.

• Horticultural Science & Technology
• /
• v.34 no.6
• /
• pp.845-859
• /
• 2016

This study was conducted to examine the effect of nighttime ventilation and heating on changes in temperature and humidity, the occurrence of white rust, and growth of standard chrysanthemum (Dendranthema grandiflorum) 'Baekma' in a greenhouse. For the ventilation treatments, the mean nighttime humidity in the control greenhouse, which had a closed side window, was higher (94.5%), but the humidity in the natural and natural+fan ventilation treatments was lower (74.3% and 72.8%, respectively). The rate of occurrence of white rust at 34 days after treatment was 100, 98.3, 75.6, and 43.3% for the control, fan ventilation, natural ventilation, and natural+fan ventilation treatments, respectively. The number of infected leaves and telia were the lowest in the natural+fan ventilation treatment compared with the other treatments. The growth of the chrysanthemum 'Baekma' was significantly suppressed in the control because of the occurrence of white rust and high humidity, while plant height, number of leaves, stem diameter, and fresh weight were the greatest in the natural+fan ventilation treatment. For the heating treatments, the mean nighttime temperature of the control (RH 95% heating), which was heating and held at 95% humidity, was $18.4^{\circ}C$, while the temperature of the heating treatment, which was held at 70% relative humidity (RH 70% heating) was $25.8^{\circ}C$. The rate of occurrence of white rust (34.4%), number of infected leaves (0.9), and telia (1.0) were the lowest in the RH 70% heating treatment compared with the other heating conditions. Also, the RH 70% heating treatment showed the best growth in terms of plant height, stem diameter, number of leaves, and fresh weight. Therefore, the natural+fan ventilation and RH 70% heating treatments were effective for the control of white rust and the growth of standard chrysanthemum 'Baekma' in a greenhouse.

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

• The Korean Journal of Pesticide Science
• /
• v.9 no.2
• /
• pp.122-131
• /
• 2005

For development of new agrochemical fungicide, syntheses of pyrrolo[2,1-b]thiazole carboxanilide derivatives 9 and antifungal screening against 6 kinds of plant pathogens were carried out. Functionalization of carboxylic acid on C-2 into carboxanilide in the pyrrolo[2,1-b]thiazole resulted in new 20 candidates, in which are ${\alpha},{\beta}$-unsaturated carboxanilide and methyl groups that are in cis relationship. Treatment of acetoxy-1,4-thiazin with magnesium in refluxing methanol gave pyrrolo[2,1-b]thiazole ethyl ester 4 in higher yield than that of the previous report. Hydrolysis of this compound afforded the corresponding acid 5, which reacted with aniline derivatives in the presence of coupling reagent, DIC to give pyrrolo[2,1-b]thiazole carboxanilides 9. As the result of in vivo antifungal assay of 9 against rice blast, rice sheath blight, cucumber gray mold, tomato late blight, wheat leaf rust, and barley powdery mildew, some compounds showed selectively antifungal activities against the rice blast and wheat leaf rust.

• Research in Plant Disease
• /
• v.14 no.3
• /
• pp.214-218
• /
• 2008

Coleosporium neocacaliae, a needle rust fungus, was described and illustrated for the first time on the needles of Pinus koraiensis (Korean pine) in Korea. Detailed descriptions of the species were verified based on symptoms and signs, and light and scanning electron microscopic observations on aecia, aeciospores and peridial cells. The present needle rust fungus was apparently different from C. eupatorii, a solely recorded Coleosporium species on P. Koraiensis in Korea until this time, in having comparatively large sized aeciospores as $20-39{\times}14-27\;{\mu}m$ than those of latter species (size of aeciospores $15-27{\times}10-20\;{\mu}m$). Verrucose surface structure of aeciospores in light microscopy was revealed to be annulated with three to four rings and root-like base in scanning electron microscopy. Aecial stage of C. neocacaliae were formed on the middle days of April to the early days of June and collected around the central parts of Korean peninsula, including high mountains of about 1,000 m above sea level.