• Korean journal of applied entomology
• /
• v.48 no.4
• /
• pp.479-484
• /
• 2009

A leafhopper, Zorka sp. was collected from a persimmon (Diospyrosi kaki, cv SangjuDungsi) orchard in Sangju, Gyeongsangbuk-do, Korea on 15 June, 2008. This leafhopper gave a serious damage to persimmon leaves, being a new pest to persimmon. This leafhopper was tentatively identified as Zorka sp., which has not been recorded in the science. White spots of <1mm-circle occurred around the vein of damaged leaves. Most part of leaf was turned to white when heavy infection occurred. The first symptom occurred from 4 days after introduction of Zorka sp. (4 adults/persimmon leaf). We investigated the occurrence of Zorka sp. in the persimmon orchards in Korea from 2008 to 2009. Total 143 orchards from 11 cities in 6 provinces were observed from July to August. The damage caused by Zorka sp. was found in 22 orchards (15.4%) of the investigated. According to locality, 40.7% of orchards were damaged in Yeongdong, Chungcheongbuk-do and 33.3% in Wanju, Jeollabuk-do. However, no damage was observed from the orchards in Gyeongsangnam-do and Jeju-do, south part of Korea. Especially, 9 of 11 orchards in Youngdong were located close to grapevine yards.

• Korean Journal of Environmental Agriculture
• /
• v.15 no.3
• /
• pp.335-340
• /
• 1996

A green house experiment was conducted to investigate the growth of Chinese cabbage, radish and soybean and change in the chemical properties of the soil after the 10mm application of the simulated acid rain(SAR) of pH 2.7 in the form of sprinkle and mist. It was applied 30 times for Chinese cabbage and radish and 62 times for soybean at the two-day intervals. The results obtained are summarized as follows: 1. Visual damages caused by SAR were dark-brown or red brown leaf spots in Chinese cabbage, and dark-brown and wrinkled leaf margins in radish and soybean. 2. The degree of visual damages became severer as the number of SAR applications increased and it was severer with mist than with sprinkle of SAR. 3. Chlorophyll content was reduced by SAR, but it was not affected by the form of SAR application(sprinkle or mist) in all crops, although it was slightly lower with mist than with sprinkle of SAR. 4. Fresh weight of Chinese cabbage heads and radish roots and grain yield of soybean were reduced by SAR, and were not affected by the form of SAR application. 5. Contents of K, Ca, and Mg in leaves were reduced, while S content increased by SAR in all crops. The forms of SAR application did not affect contents of mineral nutrients in all crops. 6. SAR decreased soil pH and the contents Ca, Mg, and K of soil, while increased $SO_4$ content. However, the contents of soil organic matter, N, and P were not affected by SAR. Forms of SAR application did not affect soil chemical properties either.

• Research in Plant Disease
• /
• v.19 no.1
• /
• pp.55-59
• /
• 2013

The purpose of this experiment was to investigate the development of new spot disease on the leaf and stem of rosemary (Rosmarinus officinalis) in commercial greenhouses at Jeonju and Namwon in Korea. Incidence of target spot on rosemary was higher at the end of the rainy season with high humidity. Those symptoms were black ring spots (3-5 mm in diameter) and withering on green leaves and stems. Conidiophores and conidia were formed on the infected tissue in moist chamber and conidia were shown as the cylindrical and oval types in chain, ranged from 55 to $275{\mu}m$ in length, and 7 to $14{\mu}m$ in width. Conidia with eight to ten pseudosepta were formed on the conidiapore. The optimum growth temperature of isolates was $30^{\circ}C$ on the PDA medium under the dark condition. In the pathogenesis test, the target spot and withering symptoms were appeared on the leaves and stems 3 days after inoculation showing similar symptoms compared to those of in nature. The same fungus was re-isolated from infected lesion, indicating that Corynespora cassiicola caused leaf target spot and twig blight on rosemary. The rDNA ITS nucleotide sequences of the pure cultured isolate from the diseased area on rosemary showed 100% similarity to the sequences of C. cassiicola available in the GenBank database (JQ595296, JQ595297, FJ852715 and AY238606). Therefore, we report that the target spot of leaves and stems in rosemary was caused by C. cassiicola.

• Research in Plant Disease
• /
• v.24 no.2
• /
• pp.123-131
• /
• 2018

Kiwifruit has been cultivated in southern coastal regions of Korea since late 1970s. New cultivars have been successively released in recent years. In this study, we investigated major disease and pest incidences in new kiwifruit cultivars 'Goldone', 'Redvita' and 'Garmrok' at open field in Sacheon for 3 years and rain-proof field in Jeju for 2 years. For the bacterial canker, the 3 new cultivars showed more disease occurrence in Sacheon but rare in Jeju. For leaf spot disease, compared to disease incidence of 20% on 'Hayward' in Sacheon, cv. 'Garmrok' had high incidence about 60% but cv. 'Goldone' and cv. 'Redvita' had low incidence less than 20%. However, in Jeju, diseases incidences of all the new cultivars were lesser than 20%. In the case of Hemiptera, many Halyomorpha halys and Nezara antennata appeared in Sacheon but in Jeju Plautia stali was dominated. Isolated bacterial canker pathogen was identified as Pseudomonas syringae pv. actinidiae biovar 3. Leaf spots pathogens were Phomopsis sp., Phoma sp., Fusarium tricinctum and Alternaria alternata. This study shows the disease information on new kiwifruit cultivars and the adequate disease managements will be required.

• Research in Plant Disease
• /
• v.22 no.3
• /
• pp.158-167
• /
• 2016

A pathogen that causes a new disease on green pumpkin in the nursery and the field was characterized and identified. Symptoms of the disease on green pumpkin were water soaking lesions and spots with strong yellow halo on leaf, brown lesion on flower, and yellow spot on fruit. The bacterial isolates from the leaf spot were pathogenic on the 8 curcubitaceae crop plants, green pumpkin, figleaf gourd, wax gourd, young pumpkin, zucchini, cucumber, melon, and oriental melon, whereas they did not cause the disease on sweet pumpkin and watermelon. They were Gram-negative, rod shape with polar flagella, fluorescent on King's B agar and LOPAT group 1a by LOPAT test. Their Biolog substrate utilization patterns were similar to Pseudomonas syringae pv. syringae's in Biolog database. Phylogenetic trees with 16S rRNA gene sequences and multilocus sequence typing (MLST) with nucleotide sequences of 4 housekeeping genes, gapA, gltA, gyrB, rpoD and those of P. syringae complex strains in the Plant Associated and Environmental Microbes Database (PAMDB) showed that the green pumpkin isolates formed in the same clade with P. syringae pv. syringae strains. The clade in MLST tree was in the genomospecies 1 group. The phenotypic and genotypic characteristics suggested that the isolates from green pumpkin lesion were P. syringae pv. syringae.

• Korean Journal of Environmental Agriculture
• /
• v.1 no.1
• /
• pp.53-58
• /
• 1982

A study was carried out to examine the effects of chlorine and hydrogen chloride gas with various concentrations (0.1, 0.25, 0.5 and $1.0\;g/m^3/hr)$ on rice and soybean plants. Symptoms, ratios of destroyed leaf, grain yield and chlorophyll contents in leaves were investigated. The results are as follows. 1) Hydrogen chloride gas damaged the margine parts of rice and soybean leaves, but chlorine appeared grayish subtle spots in whole parts of rice and soybean leaves. 2) Rice leaves showed higher damage ratio in hydrogen chloride fumigation than in soybean leaves, but less damage in chlorine. 3) Chlorophyll contents in rice leaves were higher in chlorine gas fumigated than hydrogen chloride fumigated. 4) The ratio of destroyed leaf was negatively correlated with chlorophyll contents.

• Asian Journal of Turfgrass Science
• /
• v.24 no.1
• /
• pp.9-15
• /
• 2010

During 2008~2009 winter season, yellow patch and gray snow mold occurred on turfgrass plants in golf courses in Kangwon and Jeonbuk provinces, respectively. The fungi associated with the diseases were identified as Rhizoctonia cerealis Van der Hoeven and Typhlua incarnata Lasch ex Fr., based on the morphological characteristics of hyphae and sclerotia. R. cerealis and T. incarnata were pathogenic to most turfgrass and crop species tested. R. cerealis infected crown, stem and leaf tissue of the host plants, and the symptom was light yellow circular patch. Individual infected leaf near the margin of patch developed red color first and finally turn brown. The symptoms caused by gray snow mold pathogen are water-soaked spots, and became a watery soft rot. Infection parts became yellow and then turned brown followed by death of the whole plant. White mycelia were developed on higher petioles, leaves, and on soil where these plant parts lay, and black sclerotia of variable size and shape formed in the mycelial mass. All isolates tested were pathogenic on most turfgrass and crop plants, and significantly different in aggressiveness. Disease severity increased with longer snow cover days on target plants, suggesting that disease severity was expressed over snow cover days. There were significant differences in disease severity among the graminious species, and among cultivars within each species, indicating varying levels of susceptibility to R. cerealis and T. incarnata.

• Korean Journal of Soil Science and Fertilizer
• /
• v.40 no.1
• /
• pp.31-35
• /
• 2007

In order to find out the cause of plant injury, the symptom of plant injury, and contents of element concerned in the plant were analysed. Also, a case study was conducted to find out the factor of plant injury at a agriculture and industry complex in Gyeongsang province in 2004. The distribution of isomeric curve was made with meteorological data, toxic gas concentration exhausted from pollution source. The general symptom of plant injury by ammonia gas was dry and dead of leaves with white color. At low concentration of ammonia gas, plant leaf showed spots of reddish brown. The characteristic of plant injury symptom by hydrogen fluoride gas was that the symptom was appeared at the edge of leaf. The isomeric curve of sulfur dioxide at the region, where the plant was damaged, showed that the area was affected by exhausted gas from the pollution source. Especially, this area was affected more deeply at summer than any other season.

• Korean Journal of Breeding Science
• /
• v.41 no.2
• /
• pp.145-148
• /
• 2009

Phalaenopsis (Phal.) "Yellow Dream" was developed by the National Institute of Horticultural & Herbal Science (NIHHS), Rural Development Administration (RDA) in 2005. This hybrid came from the progenies of a cross between Phal. "3031" which has yellow colored petals and small plant size, and Phal. "Golden Emperor" which has yellow colored petals with red spots and small plant size in 1995. "Yellow Dream" was finally selected in 2005 after the investigation of the growth and flower characteristics from 2000 to 2004. "Yellow Dream" had a yellow (Y4D) base color and light orange stripe petals (ORN34A) with a red lip (R42D). The average leaf length and flower width of "Yellow Dream" were 21cm and 6.8cm, respectively. It has a half erect leaf form and is a fast growing cultivar. This hybrid is relatively easy to make clones.

• The Plant Pathology Journal
• /
• v.21 no.2
• /
• pp.142-148
• /
• 2005

Whereas most of isolates of Cucumber mosaic virus(CMV) can induce green mosaic systemic symptoms on zucchini squash, foliar symptoms of a pepper isolate of CMV (Pf-CMV)-infected zucchini squash revealed systemic chlorotic spots. To assess this biological property, infectious full-length cDNA clones of Pf-CMV were constructed using long-template RT-PCR. The complete nucleotide sequences of RNA2 and RNA3 of Pf-CMV were determined from the infectious fulllength cDNA clones, respectively. RNA 2 and RNA3 of Pf-CMV contain 3,070 nucleotides and 2,213 nucleotides, respectively. Overall sequence homology of two RNAs revealed high similarity (90%) between CMV strains, and 60% similarity to those of Tomato aspermy virus and Peanut stunt virus strains. By sequence analysis with known representative strains of CMV, Pf- CMV belongs to a typical member of CMV subgroup IA. The virus has high evolutionary relationship with Fny-CMV, but the pathology of Pf-CMV in zucchini squash was quite different from that of Fny-CMV. The pesudorecombinant virus, F1P2P3, induced chlorotic spot leaf symptom and timing of systemic symptom in squash plants, similar to the plants infected by Pf-CMV. No systemic symptoms were observed when Pf-CMVinoculated cotyledons were removed at 5 days postinoculation (dpi) while Fny-CMV showed systemic symptom at 2 dpi. These results suggest that the pepper isolate of CMV possesses unique pathological properties distinguishable to other isolates of CMVs in zucchini squash.