• Korean journal of applied entomology
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• v.39 no.2
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• pp.73-82
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• 2000

Two Psyllidae species of Cacopsylla pyricola (Foerster) and C. pyrisuga (Foerster)damaging pear trees have been reported in Korea. However, their ecological characteristics and damagepatterns have not been evaluated yet. To establish basic control measures of C. pyricola, field phenology,overwintering ecology, seasonal fluctuation and temperature-dependent development of C. pyricola wereexamined. C. pyricola overwintered under the bark scale of pear trees as winter form adults and theymoved to fruiting twigs from mid-February. Honeydew produced by C. pyricola nymphs and adults asthey feed caused serious black sooty mold on leaves and fruits. The seasonal occurrence of C. pyricolawas different every year. In 1993, characterized by cold temperature and heavy precipitation, C. pyricolapopulation was maintained highly during growing season. However, the population was decreased rapidlyfrom early July in 1994, year of hot and dry weather condition. In 1995, year of average temperature, thedensity of C. pyricola population was decreased during hot months of July and August, and rebuilt up inSeptember and October. The development periods of C. pyricola eggs were 13.33 days at 15"C, 9.32 daysat 20$^{\circ}$C, 7.82 days at 25"C, 6.60 days at 30$^{\circ}$C, and 7.75 days at 35$^{\circ}$C. The development periods ofnymphs were 33.75 days at 15OC, 23.77 days at 20$^{\circ}$C, 15.21 days at 25"C, and 17.40 days at 30$^{\circ}$C. Theirdevelopment periods and mortalities were increased in higher temperatures. The parameters of nonlineardevelopment model, Weibull and linear development models of Cacopsylla pyricola were estimated.models of Cacopsylla pyricola were estimated.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.228-233
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• 2007

Pear psylla, Caccopsylla pyricola (Homoptera: Psyllidae), is a serious insect pest in pear orchards. C. pyricola overwinters as adults under rough bark scales of pear trees. When the weather warms up in the spring, the overwintered adults become active, climb up to the tree branches, and inhabit on fruit twigs to lay eggs. This study was conducted to develop a forecasting model for the onset of upward-movement of overwintered C. pyricola adults to control them by timely spraying of petroleum oil. The adult population densities were observed under rough barks (B) and on fruit twigs (T) of pear trees. Relative upward-movement rates (R) were calculated as T/(B+T). Low threshold temperatures for the activation of overwintered C. pyricola adults were selected arbitrarily from 5 to $9^{\circ}C$ at a $1^{\circ}C$ interval. Then, the days (D) when daily maximum air temperatures were above each low threshold temperature were counted from 1 February until to the dates with R $\geq$ 0.8. The same methods were applied for the prediction of the first observation of eggs. The variation of coefficients (CV) for the mean Des were lowest with the low threshold temperature of $6^{\circ}C$. At this selected threshold temperature, the upward movement of C. pyricola adults occurred with 12 D and they started laying eggs with 25 D. In the field validation, the model outputs with the $6^{\circ}C$ threshold temperature reasonably well explained the observed data in Suwon and Cheonan in 2002. Practical usages of the model were also discussed.

• Korean Journal Plant Pathology
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• v.12 no.3
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• pp.368-373
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• 1996

배나무잎 검은점병에 이병된 신고와 지표식물 PS-95의 잎을 전자현미경으로 세포내 미세구조를 검경한 결과 굴곡성 사상형 유사바이러스 입자가 집단으로 존재하고 있는 것을 확인하였다. 엽육유세포질에 있는 유사바이러스 입자들의 직경은 12 nm였으나 입자들의 길이는 측정하지 못하였다. 섬유사를 함유하고 있는 소포는 일반적으로 ssRNA genome을 갖는 식물바이러스에 의해 이병된 세포에서 생성된다. 본 연구에서 이 소포들은 tonoplast에 형성되었다. 배나무잎 검정점병의 이병잎을 초본 지표식물에 즙액접종하였으나 어떠한 병징도 나타나지 않았다. 또한 접목접종 전염에 의하여 전염되어 전형적인 검은점이 발병하였다. 발병된 잎에는 유사바이러스 입자가 존재하고 있었다. 이상의 결과 병징, 섬유사를 함유한 소포의 존재, 그리고 접목전염을 기초로하여 볼 때 배나무 검은점병을 일으키는 유사바이러스 입자는 closteroviruses의 하나로 생각된다.

• Korean journal of applied entomology
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• v.19 no.1 s.42
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• pp.39-44
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• 1980

The outbreak of the pear rust caused by Gymnosporangium haraenum SYDOW has increased gradually since 1973, and amounted to 60.3 percent infection of leaves in 1975. But it has reduced due to regulation of juniper plantings by Plant Protection Law enacted in 1974. The teliospores of C. haraeanum germinated from middle of April to middle of May under natural condition. The germination of teliospores was observed 5 day earlier under laboratory condition with the artificial rainfall than that of natural condition. It was required considerable rainfall and longer than 3hr rainy period to germinate teliospores after being matured. Infection of rear leaves took place in the rain or just after the rain, but not after 24hr. The incubation period of G. haraeanum on the leaf was 9 to 10 days. In case that the distance between orchard and juniper trees was less than loom, almost all of the pears were infected, but the chance oft infection reduced in proportion as the distance increased. No infection occurred at the distance of further than 2000m.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.205-208
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• 1996

Psylla pyricola population from Suwon($37^{\circ}$16' N) begins to enter diapause by exposure to a photoperiod of 14hr light. Over 93% of adults were induced to enter diapause when exposed to 13hr loght period, and at 18 and $25^{\circ}C$, the critical photoperiod was not influenced. When the photoperiod was switched during the nymphal stage from 16L to 10L, no morph change was occurred in the 4th and 5th instars. Average number of eggs laid per female was 486.2 in winter form adult and 387.2 in summer form adults, and average oviposition periods were 34 and 24 days, respectively.

• Korean journal of applied entomology
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• v.21 no.4 s.53
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• pp.207-210
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• 1982

The studies were carried out to examine susceptibility or resistance of junipers as an inform ediate host of pear rust, to select effective fungicides to pear and juniper rust, and to determine their application time. The telia were formed abundanty on Juniperus chinensis var. kaizuka, moderately on J. chinensis, J. chinensis var. sargentii and J. virginiana, but little on J. chinensis var. globosa and J. utilis. The telia from the junipers were pathogenic to pear. Spraying juniper host with the fungicide Actidione in the 1st and End parts of April greaty inhibited swelling of telia as well as germination of teliospores. The two or three applications of Bayleton at the end of April to May 10 were remarkably effective for the control of pear rust. Fungicide sprays just before rain were more effective than those after rain.

• Horticultural Science & Technology
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• v.19 no.1
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• pp.43-47
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• 2001

This study was conducted to investigate the integrated control strategy against pear black leaf spot disease. Using indicator plant PS-95 we selected six virus-free trees (cv. Niitaka) from commercial orchards in the major pear production area. Disease symptom by pear black leaf spot in the shoot of pear (Niitaka) has been successfully inhibited by heat treatments for 3 weeks at temperature of $40^{\circ}C$ (day) and $32^{\circ}C$ (night) or 4 weeks at $37^{\circ}C$ and $30^{\circ}C$, respectively. However, survival rate of the shoot tips on stocks was low. Seven cultivars Niitaka, Imamura- aki, Waseaka, Nijisseiki, Wasenijisseiki, Shinsetsu and Whangkeumbae produced visible symptoms in the first year after inoculation with the virus. Other 11 selections remained symptomless. Two resistant cultivars Suwhangbae and Gamcheonbae were selected, which showed high fruit quality. It is recommended that these cultivars could be top-grafted onto the infected Niitaka trees to overcome the damage caused by the disease in the orchard.

• Journal of Korean Society of Forest Science
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• v.99 no.6
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• pp.885-890
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• 2010

This study was conducted to confirm the application as ingredients of cosmetics through an examination of the function for anti-oxidant activity of the fraction isolated from Pyrus ussuriensis leaves. The dried leaf of Pyrus ussuriensis were extracted with acetone-$H_2O$ (6:4, v/v), concentrated and fractionated with the upper layer of acetone on a separatory funnel. Each fraction was freeze dried, then a portion of acetone soluble powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol as eluents and also used the MIC-gel using a series of aqueous methanol as developing solvent. The isolated compounds were identified by silica-gel TLC. The concentration of total phenolic compound of Pyrus ussuriensis acetate soluble fraction was high, 914 mg/g. The results obtained from the analyses of the anti-oxidanat effects of Pyrus ussuriensis acetate fraction can be summarized as follows: In the result of DPPH scavenging radical activity, Pyrus ussuriensis acetate soluble fraction showed more than 80% at 100 ppm. SOD-like activity of one of Pyrus ussuriensis acetate soluble fractions was 77% at 1000 ppm. Xanthine oxidase inhibition of Pyrus ussuriensis acetate soluble fraction was 38% at 100 ppm. From these results, we confirmed that acetate fraction of Pyrus ussuriensis has a great potential as a natural ingredients with a natural antioxidant and antimicrobial source.

• Journal of the Korean Applied Science and Technology
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• v.36 no.3
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• pp.685-699
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• 2019

Antioxidant, antibacterial, and skin penetration tests were conducted to investigate the skin absorption of Pyrus serotina var leaf extracts using polymer micelles and their applicability to cosmetic ingredients. Total polyphenol content was found to be $118.83{\pm}9.39mg/g$ in Pyrus serotina var leaf ethanol extract and $106.89{\pm}4.45mg/g$ in Pyrus serotina var leaf hydrothermal extract. The DPPH radical scavenging activity was found to be the highest radical scavenging activity of $74.39{\pm}7.48%$ of the Pyrus serotina var leaf ethanol extract at the concentration of 500 mg/L. The SOD-like activity was $91.62{\pm}0.43%$, the highest value at the concentration of 1,000 mg/L in the hydrothermal extract. After the experiment, antioxidation, wrinkle improvement and whitening activity were confirmed, and the Pyrus serotina var leaf extract was highly likely to be realized as antioxidant and antibacterial material. In the skin penetration experiment with the Pyrus serotina var leaf ethanol extract, the permeation amount of total accumulated tannic acid was found to be Formulation 2 ($55.45{\mu}g/cm^2$), Formulation 1 ($46.43{\mu}g/cm^2$), Formulation 0 ($34.36{\mu}g/cm^2$). In the liposome's skin penetration experiment containing pear leaf hydrothemal extract, the total amount of accumulated tannic acid permeation was found to be Formulation 5 ($75.01{\mu}g/cm^2$), Formulation 4 ($64.01{\mu}g/cm^2$) and Formulation 3 ($36.60{\mu}g/cm^2$). Through this study, we confirmed the possibility of antioxidant and wrinkle effects of Pyrus serotina var leaf extract. In addition, as a result of skin penetration through the production of polymer micelles and liposome containing Pyrus serotina var leaf extract, It will be more usable in cosmetic industry.

• The Bimonthly Magazine for Agrochemicals and Plant Protection
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• v.13 no.3 s.108
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• pp.35-41
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• 1992

최근 과수산업은 소비자의 기호에 맞게 보다 품질이 좋은 품종의 재배가 증가하고 있기 때문에 정지전정(整枝剪定), 시비, 약제방제 등 재배관리법도 그 품종에 맞도록 바뀌고 있다. 또 산업화에 따라 농촌인구의 감소, 겸업농가의 증가등 사회요인의 영향도 있어 재배관리 작업의 생력화가 강조되고 있다. 이와 같은 재배환경의 변천에 따라 배나무의 병해 발생은 늘어날 것으로 전망된다.