• Korean Journal of Organic Agriculture
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• v.19 no.2
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• pp.229-243
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• 2011

Consumers' interest and government's support for the fruits rapidly increased organic fruit productions. This study was examined to compare the soil physicochemical and microbial properties of orchards soil in conventionally and organically management systems. Organic cultivation had lower soil bulk density, solid phase, and penetration resistance than the conventional cultivation. Soil pH and organic matter contents increased from March to August, and the values were greater in the organic cultivation than the conventional cultivation. Total nitrogen (N) and phosphorous concentrations decreased from March to August, and the organic soils had greater N but lower phosphorous concentrations than the conventional soils. Soil microbial carbon biomass increased 36% and 15% for organic and conventional cultivations, respectively, from March to August. Soil microbial N biomass was greater in June than March or August, and the organic cultivation had a greater biomass N compared to the conventional cultivation. Soil dehydrogenase and chitinase activities were greater in June than in March or August. ${\beta}$-glucosidase activity declined in both cultivations, while the phosphatase activity increased. Organic cultivation had greater enzyme activities in March, June, and August, except for the acid phosphatase activity in June.

• Korean Journal of Organic Agriculture
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• v.18 no.3
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• pp.363-375
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• 2010

Sustainable farming systems have remarkably increased in Korea due to the increase of environmental concerns caused by the conventional systems. This study was performed on eight-year-old 'Niitaka' pear tree s to investigate the effects of different organic fertilizers on soil chemical and microbial properties and leaf and bud developments. Treatment and applications included 10 kg of rice bran (RB), 10 kg of coffee bran compost (CBC), 10 kg of Chitin incubated compost (Micro keeper$keeper^{(R)}$, CIC), and 30 kg of the mixture of the RB, CBC, and CIC (RCC). Control received 60 g of NPK (16-11-12) chemical fertilizer. The organic fertilizers increased organic matter, nutrient concentrations such as P, K, Ca, and Mg, and microbial biomass in soils compared to the control. RCC had the greatest specific leaf weight (SLW), and the other treatments did not have a significant difference for the SL W. Leaf P and K concentrations were different among the treatments, but they were not affected by the amounts of the soil nutrients. No differences were observed in the leaf Ca and Mg concentrations in the treatments. Organic fertilizers had greater chlorophyll contents than the control but had similar flower bud characteristics to the control.

• The Korean Journal of Pesticide Science
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• v.12 no.4
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• pp.375-381
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• 2008

A new disease causing skin sooty dapple symptoms on fruits, leaves, and young shoot of Asian pear occurred in Korea. However, no chemical control approaches has been developed to control this disease. To investigate ecological aspects of this disease, we conducted field surveys in the high or low disease occurred orchards. The years with heavy rainfall caused severe occurrence of the skin sooty dapple disease than the years with lower rainfall during all growth stages of pear fruit. Different fruit-wrapping bags did not prevent occurrence of skin sooty dapple disease, and lesion numbers were higher in lower parts of fruit equatorial line inside of fruit-wrapping bags. There is a direct correlation between occurrence of the skin sooty dapple disease and frequency of fungicide application in the orchards. Among the tested commercial fungicides, thiophanate-methyl WP and penconazole WP completely inhibited the growth of the Cladosporium sp. in in vitro studies but little protection was observed in the field following fungicide applications. However, application of lime sulfur combined with the use of fruit-wrapping bags most effectively reduced incidence of the disease in the field. Our results suggest that skin sooty dapple disease could be a serious problem in sustainable organic pear farms and effective control methods for this disease urgently required.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.16-23
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• 2011

BACKGROUND: This study was conducted to investigate the effects of different organic treatments and a chemical fertilizer on the soil chemical, physical, and microbial properties in an organic pear orchard. METHODS AND RESULTS: Control was referred as a NPK chemical fertilizer (15N-9P-10K) and organic treatments included compost containing with oil cake, compost containing with humic acid, and compost containing with chitin substance. All treatments applied at rates equivalent to 200 g N per tree per year under the tree canopy in March 30 of 2008 and 2009. Soil bulk density, solid phase, liquid phase, and penetration resistance were not significantly different among the treatments. Organic treatment plots had greater organic matter, total nitrogen, potassium, and magnesium concentrations compared to control, and the nutrient concentrations were not consistently affected by the organic treatments. Microbial biomass nitrogen and carbon, dehydrogenase, acid-phosphatase, and chitinase activities overall increased from March to August. Organic treatments, especially compost containing with oil cake or chitin aicd, increased the microbial variables compared to control. CONCLUSION(s): All the organic treatments consistently stimulated soil biological activity. The consistent treatment effect, however, did not occur on the soil mineral nutrition as the trees actively taken up the nutrients during a growing season, which would have diminished treatment effects. Long-term study required for evaluating soil physical properties in a pear orchard.

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.831-841
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• 2017

Different timings of coverage by a small paper bag at the young fruit stage were tested in order to evaluate the effect on the protection of fruit damage occurred by disease or pest, and quality deterioration during organic cultivation of 'Hwasan' (Pyrus pyrifolia Nakai) pear cultivar. The occurrence of four major moth populations and two major diseases in pears were monitored from April to September 2015. Among major moths and diseases, Grapholita molesta and pear rust were found often in the organic pear orchard, and they were observed frequently in May. Coverage by a small paper bag at the young fruit stage resulted in better fruit quality and a higher proportion of commercial fruits compared to a coverage timing of conventional paper bag. Interestingly, the fastest coverage timing of a small paper bag at the young fruit stage (when it was covered in April) showed the lowest occurrence of damaged fruits, which indicates that it successfully protected fruits from the damage caused by moths and diseases during April and May. Moreover, this timing of small paper bag coverage did not negatively affect the major qualitative and quantitative characteristics of fruits. These results suggest that early coverage by a small paper bag at the young fruit stage can be considered an efficient management strategy for organic cultivation of 'Hwasan' pear cultivar.

• Korean Journal of Plant Resources
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• v.28 no.5
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• pp.641-647
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• 2015

This study was conducted to select native ground cover plants for sod culture in an organic apple orchard by estimating the effect of three native ground cover plants, Glechoma hederacea, Thymus magnus, and Ixeris stolonifera, on the soil coverage, time-periodic weed occurrence, fruit characteristics, and soil chemical properties. The plant height of G. hederace, T. magnus and I. stolonifera were 15.0 ㎝, 13.4 ㎝ and 7.2 ㎝, respectively. The dry weight of G. hederace, T. magnus and I. stolonifera were 463 ㎏/10a, 247 ㎏/10a, and 255 ㎏/10a, respectively. The plant height and dry weight of G. hederacea were higher than in the other species. T. magnus and I. stolonifera having relatively lower soil cover rate during their life cycle produced a lot of weeds in the orchard as compared with the control. In contrast, G. hederacea showed 100 percentage of ground cover in the first year, and maintained high percentage of ground cover in the growing season of ‘Tsugaru’ apple for another 2 years. When the soil was covered with G. hederacea in the orchard for 3 years, the amount of weed was only 114 ㎏/10a and number of weeding was also reduced about 33% compared with control as well as the other species. There were no differences in the tree growth and fruit characteristics between the native ground cover plants and the control; however, positive effects of native ground cover plants on soil chemical properties were found. In G. hederacea, available P₂O₄content in soils remarkably increased and was a significant difference among native species. In addition, cation (Ca, Mg and K) content in soils increased by 39% in Ca, 6% in Mg, and 11% in K at G. hederacea compared with control. These results suggest that G. hederacea could be advantageous in terms of reducing the amount of herbicide applied and the labor required for weed control, and controlling soil chemical properties; therefore, it is a good candidate for sod culture in an organic apple orchard.

• Journal of Bio-Environment Control
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• v.21 no.3
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• pp.286-293
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• 2012

This study was initiated to find out the suitable perennial ground covers naturally grown in thirteen organic orchards in Chonnam Province as a organic nutrient source for maintaining annual fruit tree growth. The ground covers were observed in April, June, and August in the orchards. Agropyron tsukusinense and Panicum virgatum observed in April and June, respectively, produced the highest dry weight, which increased amounts of N, $P_2O_5$, and $K_2O$, mineralizing from the residue in the ground covers. The occurrence of perennial ground covers in August decreased compared to April and June. Amount of residue in mowed Agropyron tsukusinense and Panicum virgatum satisfied nutrient demand (N; 20 kg/10a, $P_2O_5$; 11 kg/10a, and $K_2O$; 19 kg/10a) to achieve the annual growth of twenty-year old fruit tree.

• Korean Journal of Organic Agriculture
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• v.26 no.2
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• pp.245-257
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• 2018

The efficacy of different control techniques against the large black chafer, Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae), in organic pear (Pyrus pyrifolia) orchards was evaluated. In this study, field trials were conducted in three locations in Korea-Naju, Hampyeong, and Boseong-to evaluate different techniques to suppress these beetles. Pheromone traps, bio-insecticides (Hongmengye and Melchungdaejang), and a combination of the two were applied as treatments. In Naju, Hampyeong, and Boseong, the highest number of adult H. parallela were caught in the control plots (n=45, n=39, and n=20, respectively), while the fewest were caught in the pheromone plus bio-insecticide plot (n=19) in Naju and in the combined treatment plot in Hampyeong (n=10). In Naju, the greatest leaf damage was observed in the control (66%), and in all locations (Naju, Boseong, and Hampyeong), the least damage occurred in the combined treatment plots (42%, 36%, and 24%, respectively). Regarding the tree canopy, the greatest leaf damage was observed in the upper canopy, and less damage was observed in the lower canopy. These results demonstrate that the combination of sex pheromone traps and bio-insecticides can be used to manage H. parallela in organic pear orchards.

• Korean Journal of Organic Agriculture
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• v.28 no.2
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• pp.209-221
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• 2020

Highbush blueberries (Vaccinium corymbosum), 'Duke', 'Bluecrop', and 'Elliott', were applied with ground cover mulch systems to evaluate bush growth and fruit characteristics. Soil temperature variation was lower in the woodchip mulching plot. Therefore, CEC, soil pH, phosphate, mineral ions were not significantly different among mulching materials. The number of main stem was higher in woodchip > sawdust > rice husk > plastic film mulching plot, respectively. Total shoot number was also higher in organic mulching plots than in plastic film plot. However, total shoot number was not significantly different among the organic mulching plots. Fruit weight was the highest in the woodchip mulching plot of all blueberry cultivars, however, soluble sugar content, organic acidity, fruit firmness were not significantly different in mulching materials. Yield was higher in organic mulching plots than in plastic film plot in all blueberry cultivars. Especially, yield per shrub of woodchip plots was the highest about 3.6 kg in 'Duke', 2.7 kg in 'Bluecrop', and 2.6 kg in 'Elliott'. Furthermore, correlation of main stem number and yield was highly significant (r² = 0.8413). Therefore, woodchip mulching is expected to be an eco-friendly method to increase the number of stems and the yield of blueberries.

• Research in Plant Disease
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• v.11 no.2
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• pp.115-121
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• 2005

This studies were carried out to elucidate the control effect of copper fungicides against some citrus diseases, assess copper spray injury on leaf and fruit of citrus by spraying of copper fungicides according to growth stages and spray seasons and by tank mixing with paraffin oil in field experiments for 3 years (2003-2005 season). As results, the control value was approximately $75\%$ against scab disease in all tested copper fungicides, $85-88\%$ to canker and $75-86\%$ to melanose. In case of leaf, the copper injury was the severest in early stage of shooting, and the injury was gradually weakened according to growth of leaf. In fruit, the copper injury was more severe in midsummer (late of July and August) than early of summer and spring season (June and ealy of July). Among copper fungicides, the bordeaux mixture which made by level of farm induced more injury compared to other copper fungicides commercialized. Less copper spray injury was observed on treatments in which copper fungicide was sprayed as tank mixtures with paraffin oil when compared to treatment which sprayed with only copper fungicide.