• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.85-89
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• 1998

Effect of soil residue paraquat (1,1-dimethyl-4,4-dipyridinium dichloride) on growth of barley (Hordeum vulgare L. cv. Sacheon No.6 and cv. Tapgolbori) and soybean [Glycine max (L.) Merr. cv. Alcheon and Danyeop] was investigated. Changes in soil residue paraquat during the cultivation period and residue amount in the p1ants at harvest were also determined. Experiments were conducted at two paraquat residue conditions; the first was done in an apple orchard soil where paraquat residue recorded 30.2 ppm in 1996, but decreased to about 9 to 9.8 ppm at the time of crop seeding and the second was conducted in the soil fortified to about 27 to 32 ppm paraquat residue. In both conditions, no crop injury due to the residue paraquat was observed and number of emerged seedlings and plant height of the two crops were not affected by soil residue paraquat. Residue amount of paraquat in the plants occurred less than 0.5 ppm detection limit. At the first condition, soil residue paraquat was further slightly decreased for 90 days after seeding, while no great change in the residue level was found at the second condition for 30 days after seeding. The results suggest that no carry-over effect occurs at about 30 ppm of soil residue paraquat and at present crop cultivation in Korean orchard soils are safe with respect to crop growth and paraquat residue in the plants.

• Journal of Species Research
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• v.5 no.3
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• pp.477-482
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• 2016

Mite of the genus Hypoaspis of family Laelapidae are free-living soil predators mostly observed on the open grass field. Five species in the genus Hypoaspis were listed in Korean Catalog (NIBR, 2013) without detail information. Recent series of soil acarine biodiversity survey in Gyeongbuk and Gangwon provinces during 2009-2015 recovered a new record of Hypoaspis sardous (Canestrini, 1884) to Korean inventory from apple orchard and riparian grass land. Detailed description and morphological comparison with the related species, H. aculeifer which is well known biological control agent of horticultural crop pests were provided with identification keys.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.30-35
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• 2014

Arctosa yasudai (Tanaka, 2000) and Pardosa isago Tanaka, 1977 belonging to Lycosidae were captured by pitfall trap in rice field and apple orchard during the intensive survey of arthropod fauna of agricultural ecosystem in Korea. Taxonomic descriptions for two species are presented with diagnostic illustration.

• The Plant Pathology Journal
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• v.37 no.3
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• pp.299-306
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• 2021

Pollination is an essential process for plants to carry on their generation. Pollination is carried out in various ways depending on the type of plant species. Among them, pollination by insect pollinator accounts for the most common. However, these pollinators have be decreasing in population density due to environmental factors. Therefore, use of artificial pollination is increasing. However, there is a lack of information on microorganisms present in the artificial pollens. We showed the composition of bacteria structure present in the artificial pollens of apple, kiwifruit, peach and pear, and contamination of high-risk pathogens was investigated. Acidovorax spp., Pantoea spp., Erwinia spp., Pseudomonas spp., and Xanthomonas spp., which are classified as potential high-risk pathogens, have been identified in imported pollens. This study presented the pollen-associated bacterial community structure, and the results are expected to be foundation for strengthening biosecurity in orchard industry.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.215-219
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• 1994

This experiment was tried for finding out some soil chemical problems when new apple trees were replanted in old orchards. Soil samples were collected from the soil horizons in the old apple orchards cultivated over 40 years and reference soils. The non-cultivated reference soils were located near the old apple orchards and each of the soils was showed as the same pedon with each of the cultivated soils. The results were as follows : Soil pH showed a tendency to decrease in low horizons of the cultivated soils whereas increase in those of the uncultivated soils. As a comparision with each chemical component, the content of exchangeable Ca or total Mn was likely to be deficient in the cultivated soils. But all components except those were not like that. Total exchangeable cations in the cultivated soils were lower than in uncultivated soils. The pH in the cultivated soils showed very high positive correlation with total exchangeable cations. From those result, it was assumed that lower pH in lower horizon which would be originated from low content of total exchangeable cations, reacts as a factor for the deterioration of old apple orchard soil.

• Research in Plant Disease
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• v.22 no.4
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• pp.269-275
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• 2016

Black shoot blight disease caused by Erwinia pyrifoliae have damaged economic loss to apple and pear growers until now since it was firstly reported in 1995 in Korea. This study was performed to reduce economic loss by mandatory eradication of all infected trees in case of more 10% disease incidence per orchard as official control. It also aims to set up effective management protocol for this disease by examining how far bacterial pathogen is present from the border of symptomatic and asymptomatic regions in infected apple twigs. Colony-PCR using isolated bacterial cells instead of genomic DNA was used to identify bacterial pathogen, EpSPF/EpSPR primer designed in enterobacterial repetitive intergenic consensus (ERIC) region was selected as specific for E. pyrifoliae. As results of monitoring of this disease during April to October in 2014-2015 by colony-PCR, occurrence of this disease was frequent from mid-May to early-July, when daily average temperature was around $25^{\circ}C$. Moreover, bacterial cells were continuously detected only in symptomatic regions and also asymptomatic regions of less than 20 cm from symptomatic regions. Therefore, we concluded that pruning of infected twigs at the region of more than 20 cm from symptomatic regions might be effective to manage black shoot blight disease in apple trees.

• Research in Plant Disease
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• v.23 no.1
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• pp.49-55
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• 2017

The previous study showed that die-back of apple trees caused by soil-borne diseases was significantly high in the apple orchards in Chungbuk province. The correlation between dieback ratio and cultivation environment in apple orchards infected by soil-borne diseases was investigated in this study. The dieback ratio of five orchards diseased by violet root rot and five places infected by white root rot showed significantly positive correlation with Ca content and available $P_2O_5$ content in soil, respectively. Whereas, the dieback ratio of fourteen orchards diseased by Phytophthora root rot was not significant. Subgrouping of cultivation environment analysis showed that the slope degree of orchard and the number of fruit setting also affected the dieback ratio caused by violet root rot and Ca content in soil also affected the dieback ratio caused by white root rot. It showed that the slope degree, soil texture, Mg and Ca content affected the dieback ratio caused by Phytophthora root rot. These results can be applied to reduce die-back ratio by the modification cultivation environment for each soil-borne disease.

• Research in Plant Disease
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• v.26 no.4
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• pp.222-228
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• 2020

Erwinia amylovora, a causal bacterium of fire blight disease, is registered as a prohibited quarantine pathogen in Korea. To control the disease, the government should diagnose the disease, dig and bury the host trees when fire blight occurs. Fire blight was the first reported in 43 orchards of Anseong, Cheonan, and Jecheon in 2015, and 42.9 ha of host trees were eradicated. However, the disease spread to eleven cities, so that 348 orchards and 260.4 ha of host trees were eradicated until 2019. Fire blight of Asian pear occurred mainly in the southern part of Gyeonggi, and Chungnam province, on average of 29±9.2 orchards per year. And the age of the infected trees were mostly 20-30 years old. In apple trees, the disease occurred mainly in the northern part of Gyeonggi, Gangwon, and Chungbuk province, on average of 41±57.6 orchards per year, increased highly in 2018 and 2019. The age of infected apple trees were under 20 years old. Therefore, because the disease spread rapidly in young apple trees, spraying control agents to the trees in a timely manner and removing infected trees quickly are important to prevent the spread of fire blight in the orchard of immature trees.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.147-156
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• 1997

The survey of weed population in apple orchard was conducted to investigate basic information on weed flora and its ecology at 27 locations in 1996. The weed species observed include 7 species of grasses, 60 species of broadleaves and 2 species of sedges, and the ratio of annual weed vs perennial weed was 64 : 36. Major dominant weed species by frequence were Chenopodium album, Capsella bursa-pastoris, Digitaria sanguinalis, Rorippa islandica, Alopecurus aequalis and Erigeron canadensis. While, on the basis of dry weight, the most dominant weeds were C. album followed by E. canadensis, A. aequalis, R islandica and R indica. The dominant weed species in middle-north Kyeongbuk region were C. bursa-pastoris, C. album, R indica and R islandica, were E. canadensis, Persicaria hydropiper, A. aequalis and Arenaria serpylliforia in Chungbuk region and were A. aequalis, E. canadenris and R islandica in Honam region.

• Korean Journal of Organic Agriculture
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• v.25 no.3
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• pp.587-602
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• 2017

Correlations of soil and leaf nutrients and growth of young 'Enterprise' apple (Malus ${\times}$ domestica Borkh.) trees were analyzed with tree damage, such as Japanese beetle (JB; Popillia japonica Newman)-damaged leaves, vole damage to trunk, tree mortality, and weed density in a certified organic orchard in warm and humid environment of Southern USA. Interaction treatments of four mulch and three fertilizers were applied around trees as follows: mow-and-blow (MB), shredded paper (SP), wood chips (WC), and green compost (GC) as a mulch, with no fertilizer (NF), poultry litter (PL), and commercial organic fertilizer (CF) as a fertilizer applied in April. Vole damage to trunk and weed density were little correlated with mineral nutrients and tree growth. JB-damaged leaves were highly stimulated to 26.5% in GC-treated plots while tree mortality were increased by MB treatments. Biomass production per tree was approximately 3,700 g on the WC- and GC-treated plots, which was two times higher than those values observed on the other two mulch plots. JB-damaged leaves tended to get worse when nutrients in soil and leaf increased through the correlation analysis, with a strong positive relationship ($r^2=0.585$) observed between JB-damaged leaves and trunk cross sectional area, a vegetative indicator. Tree mortality was more negatively associated with nutrient contents and growth of trees than those of soil nutrients. Wood chips was considered for a local organic mulch materials to increase organic matter contents and to produce healthy young trees in Southern USA, with control insect, such as beetle, and vole density in an orchard habitat.