• Horticultural Science & Technology
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• v.19 no.3
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• pp.362-366
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• 2001

This survey was carried out to investigate the effect of flooding by heavy rain on growth characteristics and disease incidence of 'Fuji'/M.26 mature apple tree in 1998 at Kyongbuk province. The surveyed regions were Andong, Uisung, and Gunwi area. The six orchards were selected from one area, totally 18 orchards were surveyed. The flooded depth of surveyed orchards was from 70 to 350 cm, and the flooded duration was from 6 to 72 h. Defoliation ratio, number of abnormal budding, and flowering per tree were increased along with the increment of flooded depth and duration. Rooting ratio was decreased rapidly with the increment of flooded duration, and dead root ratio was 16.2% in flooded orchards. Marssonia blotch (Diplocarpon mali), white rot (Botryosphaeria dothidea) of fruit, and phytophthora fruit rot (Phytophthora cactorum) incidence were increased in flooded orchards. The analysis results of pearson correlation coefficient among surveyed items showed that higher relationship of abnormal growth characteristics and increment of disease incidence of 'Fuji'/M.26 apple trees with flooded duration than with flooded depth. With these results, the flooded depth was found to be the main factor for the abnormal growth characteristics and disease incidences of 'Fuji'/M.26 apple trees.

• Korean journal of applied entomology
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• v.60 no.1
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• pp.105-114
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• 2021

Ground-dwelling arthropods are important components in apple orchard providing beneficial ecological services of predation and decomposition as well as herbivory. Groundcovers are managed differentially in organic and conventional apple orchards influencing ground-dwelling arthropod assemblages. We conducted 3-year studies to assess the effects of orchard management relative to weed management on the abundance and diversity of ground-dwelling arthropods using pitfall trapping. Most arthropods were classified as higher taxonomical groups and functional feeding guilds, while carabid beetles were classified into species level. Coleoptera was the dominating taxon of all ground-dwelling arthropods. Abundance of herbivores and predators was significantly higher in organic apple orchards than conventional ones. Higher abundance and diversity of carabid beetles were found in organic orchards than in conventional orchards. The abundance of Araneae, Coleoptera, or carabid beetles was negatively correlated to weed management frequency. It was found that ground-dwelling arthropods were more influenced by weed management practices than the farming systems.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.881-892
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• 2022

Fire blight in apple and pear orchards, caused by Erwinia amylovora, is a global problem. Ongoing outbreaks have occurred since 2015. In 2020, 744 orchards were infected compared with 43 orchards in 2015 in Korea. When are insufficient. In Korea, all host plants in infected orchards are buried deeply with lime to eradicate the E. amylovora outbreak within a few days. Apple trees with infected trunks and branches and twigs with infected leaves and infected blooms were collected from an apple orchard in Chungju, Chungbuk province, where fire blight occurred in 2020. We used these samples to investigate the population density and internal distribution of E. amylovora on infected branches and twigs during early season infections. Infected branches and twigs were cut at 10 cm intervals from the infected site, and E. amylovora was isolated from tissue lysates to measure population density (colony-forming unit [CFU]·mL^-1). The polymerase chain reaction was performed on genomic DNA using E. amylovora specific primers. Real-time polymerase chain reaction (PCR) was performed to detect E. amylovora in asymptomatic tissue. The objective of these assays was to collect data relevant to the removal of branches from infected trees during early season infection. In infected branches, high densities of greater than 10⁶ CFU·mL^-1 E. amylovora were detected within 20 cm of the infected sites. Low densities ranging from 10² to 10⁶ CFU·mL^-1 E. amylovora were found in asymptomatic tissues at distances of 40 - 75 cm from an infection site.

• Journal of Applied Biological Chemistry
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• v.50 no.2
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• pp.88-96
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• 2007

Organic farming systems based on ecological concepts have the potential to produce sustainable crop yields with no decline in soil and environmental qualities. Recent expansion of sustainable agricultural systems, including organic farming, has brought about need for development of sustainable farming systems based on value judgments for key properties of importance for farming. Chemical and microbiological properties were chosen as indicators of soil quality and measured at soil depth intervals of 5-20 and 20-35 cm in conventional and organic-based apple orchards located in Yeongchun, Gyeongbuk. The orchards were two adjacent fields to ensure the same pedological conditions except management system. Soil pH in organic farming was around 7.5, whereas below 6.0 in conventional farming. Organic farming resulted in significant increases in organic matter and Kjeldahl-N contents compared to those found with conventional management. Microbial populations, biomass C, and enzyme activities (except acid phosphatase) in apple orchard soil of organic farming were higher than those found in conventional farming. Higher microbial quotient ($C_{mic}/C_{org}$ ratio) and lower microbial metabolic quotient for $CO_2(qCO_2)$ in organic farming confirmed that organic farming better conserves soil organic carbon. Biological soil quality indicators showed significant positive correlations with soil organic matter content. These results indicate organic-based farming positively affected soil organic matter content, thus improving soil chemical and biological qualities.

• The Plant Pathology Journal
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• v.18 no.6
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• pp.342-344
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• 2002

Apple scar skin viroid (ASSVd) has been one of the most destructive diseases in Korean apple orchards. Symptoms of the scar skin viroid disease were detected in various apple cultivars, namely, Sansa, Fuji, Chukwang, Miki-Life, Hongro, and Songbongeum cultivated in the southern part of Korea. The RNA molecules were extracted from the apples bearing dapple apple symptoms with the application of CF-11 RNA extraction method. The purified RNAs were used for the synthesis of cDNA with RT-PCR. The PCR products were cloned and sequenced. The viroid RNA molecules from the six different cultivars bearing the dapple symptos showed the same nucleotide sequences as that of the Korean strain of ASSVd（ASSVd-K). ASSVd-K was detected from apple orchards in Kunwi, Sangju, Uiseong, Yeong-yang, Andong, and Youngduk in Gyeongbuk Province in 2001, and in Muju in Jeonbuk Province in 2002. As the viroid disease could be propagated vegetatively, it can be widely transmitted gradually in Korea.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.415-425
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• 2014

This study investigated population fluctuations in two mite species in apple orchards over 20-year period. The occurrence of two major mite pests infesting apple trees, two-spotted spider mite Tetranychus urticae and European red mite Panonychus ulmi (Acari: Tetranychidae), was investigated from 1992 to 2011 in major apple-producing districts, including four to eight cities, in the southern part of the Republic of Korea. The 20-year trend revealed that more orchards were infested by T. urticae from 1992 to 1999, but thereafter P. ulmi became dominant. The observed mean density of P. ulmi was consistent, whereas that of T. urticae fluctuated during this period. The analysis of occurrence in four time periods reveals that the density of T. urticae decreased after 2002. The monthly sampling, revealed that the density of P. ulmi was higher in April, whereas the density of T. urticae was higher from May to August. This change may be due to a change in the frequency of pesticide spraying, ground vegetation management, a decrease in nitrogen fertilization, and the overall orchard management practices. However, this projection should be examined in more detail. On the basis of the findings of this study, it can be concluded that cultural practices, including fertilization, and environmental changes, such as pesticide spray frequency and integrated pest management practices, affect species dominance and population densities of the two mite species in apple orchards.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.417-421
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• 2009

Monitoring was conducted to investigate the occurrence of Grapholita dimorpha Komai in Korean apple orchards using sex pheromone traps. G. dimorpa showed four peaks per year: early May, from late June to early July, from late July to mid August, and from late August to September. After adult emergence of the over-wintered G. dimorpha, G. dimorpha catches was decreased significantly and increased again after July. In G. molesta traps, G. molesta and G. dimorpha were trapped by 98.8 and 1.2%, respectively. Conversely in G. dimorpha traps, G. dimorpha and G. molesta were trapped by 99.7 and 0.3%, respectively. The 30.6% of the moths from the damaged apple fruits were G. dimorpha. This is the first report on G. dimorpha in apple orchards in Korea.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.230-237
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• 1995

Airborne and waterborne ascospores and conidia of Botryosphaeria dothidea were collected in apple orchards at Suwon and Chunan in 1992 through 1994. Both waterborne and airborne spores were first detected in mid April to early May. Thereafter, spores were abundant in early June to late August and present until early December. Rainwater collections contained much more conidia than ascospores during the apple growing seasons. Airborne ascospores catches, which were also detected on humid days without measurable rainfall, were much more than airborne conidia catches. High amounts of ascospores were detected in early times of apple growing season, whereas most conidia catches occurred in later times of the season. The number of waterborne conidia and airborne ascospores was positively correlated with mean daily maximum, minimum, and average air temperatures during the trapping periods (p=0.01). However, no significant correlation was found between the number of spores and the total precipitation during the trapping periods.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2004.05a
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• pp.159-159
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• 2004

• Current Research on Agriculture and Life Sciences
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• v.11
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• pp.91-99
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• 1993

In order to clarify the possibility of occurrence of apple replant disease and the severity of it in Kyungbuk area, 23 apple orchard soils older than 20 years were collected and growth response of apple seedlings in the soil was tested by soil fumigation. Some factors concerned with apple replant disease in some cases were also checked. The results were as follows. 1. Plant height of apple seedlings was significantly increased in 6 apple orchards and up to 38% in a most conspicuous case by soil fumigation. 2. Fresh weight of aboveground part(except leaves), underground part and whole plant(except leaves) of apple seedlings was significantly increased in 10,4 and 9 apple orchards, respectively by soil fumigation. The response of soil fumigation was pronounced in fresh weight of aboveground part of apple seedlings, more than 50% increase in 5 apple orchards. 3. The effects of available copper and arsenic content in soil and soil nematodes population on the plant height and fresh weight of apple seedlings were not recognized as important factors causing apple replant disease. 4. Effect of soil PH on the occurrence of apple replant disease was not recognized.