• Korean journal of applied entomology
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• v.25 no.2 s.67
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• pp.63-70
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• 1986

Severity of incidence of white rot on apple fruit ranged from 5 to 16% and averaged 9% over major apple growing area in 1981. An isolate of Botryosphaeria ribis obtained from rotted apples developed lesions on leaves, branches and fruits of apple, pear, peach and grape in a series of wound inoculation test. B. ribis grew well on both potato sucrose agar and oatmeal agar. The best condition for vegetative growth on these two media was at $25{\sim}30^{\circ}C$ pH 4 and $10{\sim}15%$ sucrose content under light illumination. Rot development on fruit was first observed in the orchard at early August when sugar content in fruit reached 9.0%. Thereafter, number of rotted apples increased as sugar content increased. There was no correlation between the pH of juice of fruit and rot incidence. Infection on fruit began to occur as early as mid-June when young fruits were formed and infections were continued until harvest. When apple fruits were collected at 10-day intervals from the orchard beginning from early June and were wound-inoculated with B. ribis, rot lesion developed regardless of the stage of fruit growth. Incidence of white rot in the orchard was severe on Golden-delicious and Yukou, intermediate on Aoli, Fugi and Indo, and least on Jonathan and Red-delicious.

• Korean journal of applied entomology
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• v.21 no.2 s.51
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• pp.61-67
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• 1982

The strawberry cultivar Hokowase showing rapid wilting and death around harvest time was first found in the fold at Woongcheon, Chungnam province in 1974. The fungus, Fusarium oxysporum was isolated frequently from the crown, petiole and root of strawberry plants collected from Woongcheon and was pathogenic to Hokowase. The fungus abundantly produced micro-and macro-conidia and chiamydospore on PSA. The size of micro conidia, macro conidia and Chlamydospores was $5.0\~13.0\times2.5\~3.0,\;12.8\~62.5\times2.5\times50\mu\;and\;7.5\~13.8\times5.5\~12.5\mu$, respectively. Mycelial growth of the fungus was best between $25\~30^{\circ}C$ on PSA. The disease at Woongcheon occurred from the end of March and incidence of the disease increased from the beginning of May reaching $40.2\%$ of diseased Plants at the 1st part of June. In laboratory and field evaluation tests with twelve fungicides, Difolatan, Benlate T and Tospin M showed some control effects against the disease although they did not show ignificant differences in effects compared with that of the non-treatment. The cultivar Yachiyo, Daehak 1, Line 10-2, and Senga Sengana were highly resistant, and Harunoka and Empire were moderate resistant whereas Northwest and Hokowase were highly susceptible to the fungus under field condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.2
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• pp.137-145
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• 1981

Using the milled, blast infected leaves (BIL) as an inoculum source on the screening for the resistance to blast of rice plant was a simple and useful technique. The temperature with high (25^\circ C\sim 35^\circ C) and low (15^\circ C\sim 28^\circ C) and the water stressed or not, was conditioned of to the inoculation with the BIL to the test varieties in seedling stage. In low temperature, most of the varieties were more infected with blast, however the Indica-Japonica hybrids were more infected in high temperature conditions. The water stressed was more infected with blast than the not stressed. The interaction of variety with water stress was not so much as that of variety with temperature. Resistant reaction to blast (BIL) was not affected by the temperature and water stress, but the moderately resistant or susceptible one was much affected by them. Inoculum of BIL was virulent to the newly bred Indica-Japonica hybrid cultivars such as Tongil, Nopung, etc, but not virulent to the Japonica cultivars such as Nongbaek, Jinheung, etc. The discrete, mixed or variable lesions were observed mainly in the moderately resistant or susceptible cultivars such as Kanto 51, Yashiromochi, Ishikari-shiroke, etc.

• Korean Journal of Breeding Science
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• v.42 no.4
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• pp.374-380
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• 2010

In order to select excellent cross parents in strawberry breeding, 11 varieties were self-pollinated and tested their progenies. Among the 11 varieties, 'Akihime', 'Maehyang' and 'Seolhyang' showed superior in plant vigor, disease resistance and yield. Combining ability was tested using 15 progenies obtained from crosses between 3 selected varieties as seed parents and 5 varieties as pollen parents. Plant vigor was the strongest when 'Akihime' was used as a seed parent while ripening time tended to the fastest when 'Seolhyang' as a seed parent. Average fruit weight of the crosses 'Seolhyang' ${\times}$ 'Tochiotome', 'Seolhyang' ${\times}$ 'Geumhyang', 'Seolhyang' ${\times}$ 'Wongyo 3111' and 'Akihime' ${\times}$ 'Wongyo 3111' were above 18 g for marketable fruits. Fruit hardness was superior at crosses of 'Maehyang' as a seed parents to other crosses combinations, especially 'Maehyang' ${\times}$ 'Tochiotome'. Soluble solid contents (SSC) was not significantly different among cross combinations. The best cross combination for marketable yield was 'Akihime' ${\times}$ 'Wongyo 3111', followed by 'Seolhyang' ${\times}$ 'Geumhyang', 'Maehyang' ${\times}$ 'Geumhyang', 'Akihime' ${\times}$ 'Tochiotome', in order.

• The Korean Journal of Mycology
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• v.5 no.1
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• pp.13-19
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• 1977

In order to investigate histopathologically the nature of varietal resistance and infection process of the rice bast fungus, Pyricularia oryzae. this experiment was undertaken by using the resistant cultivar Tongil and susceptible cultivars Norin No.6 and Jinheung in 1973 to 1974. 1) It was found that appressorium of the fungus forms not only at 4 hours after incubation under the favorable conditions but also peak of appressorial formation is at 48 hours treatment. Physical stimulus known to be a definite factor for appressorial formation. The optimum temperature range for appressorial infection was at $24^{\circ}C$ to $28^{\circ}C$, and pH was between 4.8 to 8.0 with 6.8 as the optimum. 2) Although percent of appressorial formation on the leaves of resistant Tongil and susceptiible Norin No.6 were only slightly different, there was a remarkable difference between resistant and susceptible cultivars with regard to percent of hyphal infection and index for hyphal extension. Index of hyphal extension was 1.6-2.7 in Tonyil. while in susceptible cultivar was 3.4-6.6. The rate of discoloration of infected cells, a indication of hypersensitivity, was greater in the resistant than in susceptible cultvar. 3) Therefore, it could be concluded that resistance of Tongil cultivar may be attributable to a higher degree of mechanical barriers as well as a higher level of antifungal substance accumulation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.176-184
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• 2019

The rice variety Chucheongbyeo is mostly cultivated for organic farming in the central region of Korea. This variety is more delicate than the recently developed varieties in rice yield, quality, and pest resistance, and is therefore, not suitable for organic farming. This study was conducted to select suitable varieties for organic rice farming in the central plain area of Korea. We tested 15 different varieties in the organic paddy field of Cheongju city from 2011 to 2013. As the experimental field had good fertility because it had been organically managed for many years, culm length and number of panicles developed better than the varietal characteristics. Daebo, Chinnong and Hyeonpum had slightly lower ripened grain ratio than Chucheongbyeo. The milled rice yield of Samkwang, Sukwang, Haiami, Cheonghaejinmi and Daebo increased by 9-18% compared to that of Chucheongbyeo. The protein content was under 7% for Cheongnam, Sukwang, Daebo, Samkwang, Hyeonpum, Chinnong, Chilbo, Hopyung, Hwangkeumnuri, Suryeojinmi and Jinsumi and under 6% for Sukwang and Samkwang. The whiteness was over 40 in Sukwang, Daebo, Samkwang and Jinsumi. The palatability grade and head rice ratio were good in Daebo, Sukwang, Samkwang and Jinsumi. Therefore, this study recommended Samkwang, Daebo, and Jinsumi as the optimal varieties for organic rice farming in the central plain area of Korea. These varieties could replace Chucheongbyeo, which is inferior to the recently developed varieties in terms of disease and pest resistance and yielding performance.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.49-60
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• 2018

Here, we reported 159 varieties of major cultivars using grapevine genetic resources to identify the resistant grape ripe rot cultivars. To do this, we performed pathogenicity assays from these grape cultivars by inoculating Colletotrichum acutatum and Colletotrichum gloeosporioides. Genotyping-by-sequencing(GBS) method was also used to compare genetic diversity among grape varieties. As a result, leaves inoculated with C. acutatum showed that 58 cultivars were susceptible, while 17 cultivars were resistant. In the case of C. gloeosporioides, 34 cultivars were found to be susceptible, while 25 cultivars were resistant. The 8 cultivars that showed resistance to both species were 'Agawan', 'Huangguan', 'Xiangfei', and 5 other cultivars from the hybrids of European and American species. Most of the varieties such as 'Emerald Seedless', 'Tano Red', and 'Rem 46-77(Aestivalis GVIT 0970)' originated in European species were identified as susceptible. These results can be used in the effective management of grape disease. In addition, these findings provide information for the development and cultivation of resistant to grape ripe rot disease cultivars.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.356-369
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• 1985

In Korea, inevitable researches for the blast control exactly started from 1927 by the organization of Office of Rural Development with the local extensive outbreak of panicle blast at Jeonlla Buk-Do Province in 1926. At present, the rice blast is still one of the most destructive and widespread diseases in spite of considerable contributions by rice scientists, particularly plant pathologists during last 55 years in Korea. Rice blast control and management are very difficult because of the marked variability in pathogenicity of the blast fungus. From the results obtained through the disease surveys during last 70 years, different 3 prevalence type of blast such as bimodal leaf-blast type, bimodal panicle-blast type and bimodal continual blast type were recognized. In generally speaking, pattern of blast outbreak is said to be characterized by severe outbreak of panicle blast after slight outbreak of leaf blast with discontinuity between leaf and panicle blast. So we have to pay much attention for successful management of panicle blast giving direct influence to rice yield. Main factors induce blast epidemic were pointed out to be breakdown of the disease resistance, nutritional unbalance such as excess application of nitrogen, delay of transplantation and longspell of rain fall by extensive surveys and researches on blast during last 70 years in Korea. The fact some of Japonica varieties such as Kokuryomiyako, Tamanishiki, Ginbozu and Pungok belong to varietal group A had been cultivated with extensive acrage over 30 years in this country should be mentioned by Korean rice scientists. Differences in field resistance between varieties in the same group are detectable and apparently small but sometimes epidemiologically significant differential effects may be found out in case of blast. Much more attention should be payed to accumulate the knowledges on field resistance for successful management of blast. Excess application of nitrogen is more effective to outbreak of panicle blast than that of leaf blast of IR varieties. In comparatively low level application of nitrogen infection rate of panicle blast of IR varieties is considerably high. Low temperature effects on outbreak of blast is very great. It results in remarkable increase of the inoculum potential on the leaf lesions and infection of panicle blast in leaf sheathes of IR varieties during the booting stage. In economic point of view, it is concluded that 5 times sprays of effective fungicides including 3 times before and 2 times after heading is good enough to control blast. We have experienced no one of control measures for blast is superior to all others. The integrated control measures was established as guideline of blast control around 1950 in Korea. This guideline must be helpful for rice growers as long as rice growing continue.

• Korean Journal of Agricultural Science
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• v.15 no.1
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• pp.36-46
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• 1988

Twelve soybean cultivars were cultivated in the 1/2,000a. Wagner pots with irrigation and without irrigation for 30 days after flowering, and the differences of plant growth and bean yield among cultivars were compared. And to investigate the varietal differences in the rate of photosynthesis under different relative humidity, 6soybean cultivars were cultivated in 1/2,000a. Wagner pot and the rate of photosynthesis of each soybean cultivar at flowering time was measured under the relative humidity of 80, 70, 60, 50 and 40%. The results obtained are summarized as follows; 1. The days to maturity of the soybean cultivars were shortened by non-irrigation treatment. The response of the maturing dates to non-irrigation was significantly different among the soybean cultivars. The days for maturing of Paldal, Danyeob and Eundaedu were delayed 2 days but those of Jangbaek and Tamahomare were delayed about 7 to 8 days under non-irrigation treatment. 2. The stem length, stem diameter, number of nodes of the mainstem, number of branches and number of branch nodes of all soybean cultivars were decreased by non-irrigation treatment. The number of branches and the number of branch nodes were especially severely influenced by non-irrigation treatment. 3. The number of pods per plant and the number of perfect pods was significantly reduced by non-irrigation treatment but the number of imperfect pods was increased. The non-irrigation treatment reduced the number of pods per plant by 58.0% and the ratio of the number of the perfect pods per plant by 46.6% relative to the ordinary cultivation with irrigation. 4. The grain yield of all cultivars was significantly reduced by the non-irrigation treatment, and average grain yield of soybean cultivars cultivated under non-irrigation treatment was 35.9% of that of soybean cultivars cultivated with irrigation. The influence of non-irrigation treatment was lowest in Paldal and significantly high in Tamahomare and Jangbaek. 5. The rate of photosynthesis of soybean leaves was significantly different among cultivars and was also influenced by relative humidity. Ratio of the photosynthetic amount of soybean leaves at 40% RH to the maximum photosynthesis at optimal humidity was 97.2% in Paldal, 96.4% in Danyeob and 88.8% in Baekun. 6. At 40% relative air humidity, highly significant correlations were found among the photosynthesis rate, the amount of transpiration and the respiration rate.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.242-252
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• 1985

In order to get information on the ecology of rice false smut, germination ability and pathogenicity of sclerotia and chlamydospores of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. The degree of outbreak of rice false smut was higher in the upland rice in comparison with the paddy field rice in respect to the number of affected grains per ear, the size and weight of smut balls formed on affected grains as well as the ratio of sclerotial formation produced on smut balls. 2. Germination percentage and days required for germination of overwintered sclerotia placed on the soil surface in July were 81% and 19 days, respectively, while those of overwintered sclerotia treated in May were 60-70% and 41 days. Sclerotia placed on the soil surface or under 1 cm depth of the soil surface and incubated at $25-30^{\circ}C$ were germinated well, whereas those placed under 3 cm or 5 cm depth of the soil surface were not germinated at all. Germinability and stroma productivity of sclerotia were reduced when the sclerotia were cutted into small pieces. 3. The average number of stroma formed on a sclerotium was six and that of perithecia formed in a stroma was about 50 to 140. 4. Percentage of germination of chlamydospores on the yellow balls was very high and was decreased as the color of the balls being darken with maturation. 5. Panicle of rice plants were successfully infected by injection inoculation with suspention of ascospores and chlamydospores of the pathogen to the sheaths at the booting stages, while seeding infection by spraying with suspensions of chlamydospores was unsuccessful. 6. More number of infected grains was distributed on basal parts of an affected ear than that of infected ones distributed upper parts of the ear, when the affected ear was divided into five parts from its basal portion to the apical of the ear. 7. The occurrence of the disease was more severe in the late maturing varieties of rice in comparison with the early maturing varieties. 8. When the level of nitrogen applied was increased, the incidence of disease increased, and the infection percentage of the disease was increased as the transplanting date was delayed. 9. The weight of panicles and 1000 kernels and the ratio of ripenness were reduced, and the contamination degree of grains with chlamydospores were increased as the number of smut balls per panicle were increased.