• Title/Summary/Keyword: Field Citrus

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Effects of Using Bio-Sulfur on Open Field Citrus Melanose (Diaporthe citri) and Panonychus citri (바이오 황의 노지 감귤 검은점무늬병 및 귤응애에 대한 효과)

  • Oh, Myung-Hyup;Park, Won-Pyo;Hyun, Hae-Nam
    • Journal of Environmental Science International
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    • v.29 no.10
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    • pp.997-1002
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    • 2020
  • In this study, we investigated the effects of the eco-friendly chemical bio-sulfur, on the citrus melanose-causing pathogen, Diaporthe citri, and on the pest, Panonychus citri. In an open field experiment with a plot-scale application of the chemicals: Mancozeb, lime sulfur, lime sulfur + machine oil, and bio-sulfur, the control group showed 70.6% disease severity compared with 10.3% for the Mancozeb-treated group. Among the eco-friendly treatments, disease severity was the lowest for the group treated with lime sulfur + machine oil (32.2%) and was 53.9%, 58.8%, and 58.1% following treatment with lime sulfur, and bio-sulfur diluted 500 and 1000 times, respectively. The proportion of diseased fruit showed similar results, suggesting that bio-sulfur is an effective alternative to lime sulfur. Three days after treatment acaricidal effects on P. citri showed a 197.6% control survival rate whereas the machine oil, and bio-sulfur diluted 500 and 1000 times treatments showed rates of 2.9%, 5.8%, and 9.0%, respectively. After three days, the control value for bio-sulfur diluted 1000 times was 73.2% compared with the values for the machine oil (96.4%) and bio-sulfur diluted 500 times (94.6%) treatments. Therefore, we suggest that additional research is needed on the combined application of bio-sulfur and oils to enhance the additive control effect on citrus melanose and Panonychus citri.

Suppression of Citrus Melanose on the Leaves Treated with Rhizobacterial Strains after Inoculation with Diaporthe citri (식물근권세균 처리에 의한 감귤 검은점무늬병에 대한 방제 효과)

  • Ko, Yun Jung;Kang, So Young;Jeun, Yong Chull
    • Research in Plant Disease
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    • v.18 no.4
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    • pp.331-337
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    • 2012
  • Citrus melanose is one of important disease in citrus cultivation, reducing quality of citrus fruits and resulting in economic loss. Like other diseases in citrus, melanose was mainly protected by chemical fungicide in the field. Recently, alternative method of disease control is highly required due to the side effect of the chemicals. In this study four rhizobacterial strains TRH423-3, MRL408-3, THJ609-3, and TRH415-2 are selected by dual-culture testing its antifungal activity against Diaporthe citri causing citrus melanose. To investigate the protection efficacy of the selected rhizobacterial strains to citrus melanose, the bacteria were pre-treated on citrus leaves following inoculation with melanose pathogen. Pre-treatment with all selected rhizobacterial strains showed disease suppression in which the levels of protection rates were different by the rhizobacterial strains. Additional treatment with the rhizobacterial strains after the pathogen inoculation enhanced protection rates in all cases. The strain MRL408-3 and TRH423-3 were identified as Burkholderia gladioli, TRH415-2 as Pseudomons fluorescens and THJ609-3 as Pseudomonas pudia as a result of analyzing the internal transcript spaces of the rhizobacterial strains rDNA. The selected rhizobacterial strains may be valuable as biological control agents in the environment-friendly citrus farm in which chemical application is limited.

Study on the over-wintering stage of citrus leaf miner Phyllocnistis citrella Stainton(Lepidoptera: Gracillariidae) in Jeju, Korea (제주도 노지재배 감귤원 내 귤굴나방 월동태 구명)

  • Soon Hwa Kwon;Kihye Shin;Young Eel Moon;Doog-Soon Kim
    • Korean Journal of Environmental Biology
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    • v.39 no.4
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    • pp.542-549
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    • 2021
  • Citrus leafminer (Phyllocnistis citrella) is an economically important pest in citrus orchards. This study was conducted to elucidate the over-wintering stage of P. citrella through experiments on the survival rate of P. citrella at low temperatures and field investigations during the winter season. There was a significant difference in the survival period depending upon the over-wintering stage of P. citrella at low temperatures, and the adults survived longer than the pupae. Evaluation of the survival period after inoculating citrus orchards with P. citrella adults and pupae showed that only the adults survived until mid-March of the following year, but all pupae died in January. This suggests that considering the fact that the germination of spring shoots in Jeju generally begins in mid-March, over-wintering adults are likely to form an early population the next year. However, pupae may not contribute to the formation of the initial population in the early season after wintering in fall shoots that are prone to freezing damage in winter because P. citrella could only survive in pupal chambers formed in fall shoots. Therefore, these results suggest that P. citrella adults that emerge in late autumn can over-winter in citrus orchards in Jeju, Korea.

Improvement of Control Efficacy of Mancozeb Wettable Powder against Citrus Melanose by Mixing with Paraffin Oil (파라핀유와 혼용 살포에 의한 만코제브 수화제의 감귤 검은점무늬병 방제 효과 증진)

  • Yi, Pyoung-Ho;Hyun, Jae-Wook;Hwang, Rok-Yeon;Kim, Kwang-Sik
    • Research in Plant Disease
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    • v.20 no.3
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    • pp.196-200
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    • 2014
  • This study was carried out to determine the effect of mixing with paraffin oil on rainfastness of mancozeb on citrus fruits and assay the improvement of control effect of mancozeb against citrus melanose by mixing with paraffin oil. In artificial rainfall condition (7.2 mm/hr), the attached contents of mancozeb on detached fruits were the most in treatment of mancozeb 0.2% + paraffin oil 0.1% as the contents was $7.43{\mu}g/cm^2$ after treatment of rainfall for 10 hr. In open field condition, the contents of attached mancozeb on fruits were significantly more in treatment of mancozeb 0.2% + paraffin oil 0.1% or 0.25% than the other treatments 1, 15 and 25 days after treatment 2009 and 2010 seasons. The disease incidence was significantly lower in treatment of mancozeb 0.2% + paraffin oil 0.1% or 0.25% than treatment of mancozeb 0.2% only 2009, 2010 and 2011 seasons. Based on this study, it was suggested that the control effect of mancozeb against citrus melanose can be improved by mixing with paraffin oil.

The Distribution Pattern of Eggs and Larval Survival Rate of Phyllocnistis citrella (Lepidoptera: Gracillaridae) on the Leaves of Shoots in a Citrus Orchard in Jeju (제주 감귤원에서 귤굴나방 알의 신초 잎 위치별 분포와 유충의 생존률)

  • Hyun, Seung Young;Kim, Su Bin;Kim, Dong-Soon
    • Korean journal of applied entomology
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    • v.58 no.3
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    • pp.175-182
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    • 2019
  • The citrus leafminer, Phyllocnistis citrella (Lepidoptera: Gracillaridae), is an important pest that decreases the productivity of citrus trees by attacking citrus leaves, and especially it causes a severe damage during the young growth stage. In this study, we investigated the distribution of eggs on the leaves of shoots according to the position and the survival rate of this pest in the field condition. The occurrence patterns of P. citrella eggs in citrus orchards were largely affected by the occurrence of shoots. Even if the adults were still being attracted in the pheromone traps, the eggs were not observed on leaves when the growth of shoots was stopped. The density of P. citrella eggs in the citrus shoots peaked at the fifth or sixth leaf from the terminal leaf, and over 90% of the eggs were found in the first to eighth leaves as a whole. In 2015 and 2016, the average survival rate of larvae surviving to pupa was 1.4%, and the rate of survival to adults was 0.2%, indicating that most of them died. Furthermore, we have discussed the management strategy of P. citrella considering the distribution of eggs and the larval survival rate in the citrus shoots.

Development of Artificial Intelligence Model for Predicting Citrus Sugar Content based on Meteorological Data (기상 데이터 기반 감귤 당도 예측 인공지능 모델 개발)

  • Seo, Dongmin
    • The Journal of the Korea Contents Association
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    • v.21 no.6
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    • pp.35-43
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    • 2021
  • Citrus quality is generally determined by its sugar content and acidity. In particular, sugar content is a very important factor because it determines the taste of citrus. Currently, the most commonly used method of measuring citrus sugar content in farms is a portable juiced sugar meter and a non-destructive sugar meter. This method can be easily measured by individuals, but the accuracy of the sugar content is inferior to that of the citrus NongHyup official machine. In particular, there is an error difference of 0.5 Brix or more, which is still insufficient for use in the field. Therefore, in this paper, we propose an AI model that predicts the citrus sugar content of unmeasured days within the error range of 0.5 Brix or less based on the previously collected citrus sugar content and meteorological data (average temperature, humidity, rainfall, solar radiation, and average wind speed). In addition, it was confirmed that the prediction model proposed through performance evaluation had an mean absolute error of 0.1154 for Seongsan area and 0.1983 for the Hawon area in Jeju Island. Lastly, the proposed model supports an error difference of less than 0.5 Brix and is a technology that supports predictive measurement, so it is expected that its usability will be highly progressive.

Analysis of Essential Oils from the Peel of Mandarine (Citrus unshiu Marc. Var. Okitsu) (온주 밀감의 껍질로부터 정유의 분리 및 분석)

  • Kim, Yu-Kyoung;Hyun, Seung-Won;Ko, Young-Hwan
    • Korean Journal of Food Science and Technology
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    • v.31 no.5
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    • pp.1178-1183
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    • 1999
  • Essential oils were isolated from the peel of mandarin (Citrus unshiu Marc. Var. Okitsu) cultivated in Cheju Island. Among three different isolation methods investigated, simultaneous distillation gave higher yield 1.14%(w/w) than solvent extraction or cold pressing. The densities of essential oils were between 0.8409 and 0.8530, which showed no significant effect of the isolation methods. Some variations in the number of constituents detected and the content of d-limonene in the peel oils were observed depending upon the isolation methods. The citrus fruit was collected seasonally from the field and used as a sample for analysis. The peel thickness and the peel content of citrus fruit were around 2 mm and about 17% on wet weight basis, respectively, in harvest season. The maximum yield of essential oils was obtained in September from citrus peels just prior to ripeness and thereafter the yield had a tendency of decrease but remained over 1%(w/w). The relative content of d-limonene, the major constituent of citrus peel oils. increased gradually with ripening up to 68.69%(relative peak area, RPA). The other minor constituents were ${\gamma}-terpinene,\;{\beta}-elemene$, farnesene, hexadecanoic acid, ${\alpha}-pinene,\; {\beta}-myrcene$ and linalool in the decreasing order of their own contents of 7.75, 2.96, 2.29, 1.76, 1.63, 1.56 and 1.46%(RPA).

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Studies on Physiology, Ecology and Protection of Citrus Canker Caused by Xanthomonas axonopodis pv, citri

  • Lee, Seong-Chan;Hyun, Jae-Wook;Kim, Dong-Hwan;Kim, Kwang-Sik;Lim, Han-Chul
    • Proceedings of the Korean Society of Plant Pathology Conference
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    • 2003.10a
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    • pp.124-124
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    • 2003
  • Citrus canker is very important disease in international trade of citrus. The disease was usually take place from late of June, and severe middle of July to middle of August, though disease occurrence was affected by environmental conditions. In pathogenicity test, three varieties, orange, lemon and kiyomi among 7 varieties, were succeptible, two varieties, satsuma mandarin and iwasachi, intermediate resistant. On the other hand, shiranuhi and yuzu were resistant relatively. The pathogen, Xanthomonas axonopodis pv. citri, grew well in PD broth adjusted to pH 7.0 at 26$^{\circ}C$. It's growth was best in medium containing group of monosaccharide as a carbon source and group of ammonium as a nitrogen source. Tow isolates were resistant to streptomycin among 11 isolates isolated from diseased leaves in field in Jeju-Do. The streptomycin sensitives isolate was controlled by in greenhouse test. On the other hand, the resistant and sensitive isolates were controlled by treatment with copper sulfate, the control value is 88.7% and 90.6%, respectively.

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Seasonal Occurrence of Yellow Tea Thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) in Citrus Orchards and Its Damage Symptoms on Citrus Fruits (노지재배 감귤에서의 볼록총채벌레 발생 양상과 피해 증상)

  • Hyun, Jae-Wook;Hwang, Rok-Yeon;Lee, Kwan-Seok;Song, Jeong-Heub;Yi, Pyoung-Ho;Kwon, Hyeog-Mo;Hyun, Dong-Hee;Kim, Kwang-Sik
    • Korean journal of applied entomology
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    • v.51 no.1
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    • pp.1-7
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    • 2012
  • Silver-grey or dark brown scaring, or dark brown discolored damages caused by the yellow tea thrip, $Scirtothrips$ $dorsalis$ Hood (Thysanoptera: Thripidae) have occurred on citrus fruits cultivated in the open field in east-south area orchards of Jeju Island since 2007. The weekly population of yellow tea thrips adults caught with a yellow sticky trap increased gradually from early May and peaked in late August, 2009. In 2010 and 2011, the most population was in early October. The yellow tea thrips of some species usually dominated from July in open citrus fields, and seven generations, at least, had occurred from May to late October 2009 by a yellow sticky trap survey. In 2009, $S.$ $dorsalis$ larva were observed from July and with peaks from late August to mid September and early October on citrus fruits. The damage symptoms appeared in the mid September. In 2011, the population peaks were in early July and late September, and the symptoms increased continually from mid July to late October. The symptoms were silver-scars or initial dark discolorations and then gradually changed to dark-brown discolorations or dark-brown scars. The percent of damaged fruits were 0.9%, 0.4%, 0.8% and 2.7% in 2008, 2009, 2010 and 2011, respectively, by survey in 64 typical orchards in Jeju Island. We are the first to report symptoms of the yellow tea thrip ($Scirtothrips$ $dotsalis$) on citrus fruits.

Effect of the Harvest Season on the Yield and Growth of Unripe Fruit and Biennial Flowering of 'Miyagawa' Satsuma Mandarin in Open Field Cultivation (노지재배 풋귤 수확시기가 수량과 과실생육 및 다음해 착화에 미치는 영향)

  • Kang, Seok-Beom;Moon, Young-Eel;Yankg, Kyung-Rok;Joa, Jae-Ho;Lee, Hae-Jin
    • Korean Journal of Environmental Agriculture
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    • v.38 no.4
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    • pp.314-320
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    • 2019
  • BACKGROUND: As consumption of unripe mandarin increases, its cultivation has increased in open field cultivation areas. Because unripe mandarin must be harvested before ripening and color change, the optimum harvest time must be determined. This study investigated the effect of the harvest season on the yield of unripe fruit and biennial flowering of 'Miyagawa' satsuma mandarin. METHODS AND RESULTS: Two areas of unripe mandarin orchard were selected, and the yield, fruit growth, working time, and flowering of trees the following year were investigated. Fruit was harvested at 40, 60, 80, 100, and 120 days after full bloom and at general ripening. Fruit yield of unripe mandarin increased with later harvest time from 100th to 120th day except normal ripening. The next year, biennial occurred with normal ripening and harvesting, but not at the 120th day after full bloom. At the 40th day (earliest harvest time), summer and autumn shoots were present, but not after the 100th day. The 40th day required the most harvesting time; because the time gradually decreased with later harvest, the harvest time was shortest on the 120th day, and general ripening occurred shortly after the 120th day. CONCLUSION: Harvesting of unripe mandarin 100-120 days after full bloom was ideal to reduce harvesting time, enhance yield, and enable flowering the following year.