• Research in Plant Disease
• /
• v.18 no.4
• /
• pp.338-348
• /
• 2012

Potato late blight caused by Phytophthora infestans Cooke is one of the major diseases in the cultivation of potatoes in Korea. Effect of chitosan preparations (SH-1 and SH-2) was evaluated on the inhibition of mycelial growth of P. infestans, and protective activity using detached potato leaf assay both in vivo and in the field test. SH-1 and SH-2 were showed protective activity of young plant with control values more than 95% potato late blight by inoculation with pathogens under growth chamber conditions. Mycelial growth was inhibited the radial growth over 74% at a concentration of $300{\mu}g/ml$ of both SH-1 and SH-2. Spraying with SH-1 and SH-2 on the leaves for detached leaf assay reduced disease development. The content of total polyphenol in stem was significantly increased by SH-1 and SH-2 application in the field. In field experiments, foliar application with both SH-1 and SH-2 were significantly reduced the development of late blight on potato plants. Control of late blight disease was obtained with control values of 72% and 53% by application of 1% SH-1 and SH-2, respectively, with 4 times at 7 days interval, and reduced with similar disease control values by application with 3 times at 14 days interval compared with untreated control. SH-1 and SH-2 applications increased the fresh weight of potato, and higher grade potatoes were also increased. The results showed that SH-1 and SH-2 applications can be used as eco-friendly natural fungicide for organic farming for the increase of yields and control of late blight.

• Korean Journal Plant Pathology
• /
• v.13 no.3
• /
• pp.145-151
• /
• 1997

An unusual young fruit rot of apple caused by two species of Phytophthora was epidemic from late May to early July of 1996 in Andong, Uisung and Chungwon areas of Korea. The disease spread to over 30 apple orchards in the areas and percent of the infected tree and fruit was ca. 10~90% and 1`15%, respectively. Water soaking lesions or spots on leaves and shoot blight were also developed by the pathogen. Among 39 isolates collected, 25 were identified as P. cactorum and the others were as zp. cambivora on the basis of their distinctive morphological characters. While the former fungus was homothallic, all isolates of the latter were A1 mating types. Koch's postulate was fulfilled. Both fungi showed strong pathogenicity not only to young fruits, leaves and shoots of apple but also to those of pear and peach. Several vegetables tested did not show symptoms even by wound inoculation. An Occurrence of young fruit rot of apple caused by Phytophthora has not been reported in Korea, especially, P. cambivora has not been recorded previously as the causal agent of the disease in the world.

• Research in Plant Disease
• /
• v.17 no.2
• /
• pp.129-135
• /
• 2011

Chitosan is a linear polysaccharide composed of randomly distributed ${\ss}$-(1-4)-linked D-glucosamine and Nacetyl-D-glucosamine. There have been many reports on the induced systemic resistance and in vivo antifungal activities of higher molecular weight chitosans with molecular weights over 3,000 amu (atomatic mass unit), but there are few papers on in vivo antifungal activities of low molecular weight chitosans (oligochitosans) with molecular weights less than 3,000 amu. In our study, an oligochitosan sample (320.3,000 amu) showed a potent 1-day protective activity with control values more than 94% at concentrations of 500 and 1,000 ${\mu}g$/ml especially against tomato late blight caused by Phytophthora infestans under growth chamber conditions. It also displayed a moderate 1-day protective activity with control values of 67.89% at concentrations of 500 and 1,000 ${\mu}g$/ml against wheat leaf rust and red pepper anthracnose. On the other hand, it showed a 16-hr curative activity against red pepper anthracnose, but not against tomato late blight and wheat leaf rust. In field experiments, oligochitosan effectively suppressed the development of late blight on potato and tomato plants with control values of 72% and 48%, respectively. The results strongly indicate that oligochitosan can be used as an eco-friendly organic material for the control of late blight on tomato and potato plants.

• Research in Plant Disease
• /
• v.17 no.2
• /
• pp.121-128
• /
• 2011

Bacteriolytic myxobacteria have been known to secrete various antifungal metabolites against several soilborne phytopathogens including Phytophthora. Among the three isolates of Myxococcus spp., KYC 1126 and KYC 1136 perfectly inhibited the mycelial growth of Phytophtora capsici in vitro. In order to show the biocontrol activity on Phytophthora blight of hot pepper, we tried to find the best way of application of a myxobacterial isolate. Although KYC 1126 fruiting body was easily grown on the colony of Escherichia coli as a nutrient source, it did not control the disease when it was pre-applied in soil. Before the bioassay of a liquid culture filtrate of KYC 1126 was conducted, its antifungal activity was confirmed on the seedlings applying with the mixture of the pathogen's zoospore suspension and KYC 1126 filtrate. On greenhouse experiments with five and four replications, the control value of KYC 1126 on phyllosphere and rhizosphere was 88% and 36%, respectively. Whereas, the control value of dimetnomorph+propineb on phyllosphere was 100% and that of propamorcarb on rhizosphere was 44%. There was a phytotoxicity of the myxobacterial filtrate when seedlings were washed and soaked for 24 hours. Gummy materials were covered with roots. And stem and petiole were constricted, then a whole seedling was eventually blighted.

• Research in Plant Disease
• /
• v.17 no.1
• /
• pp.1-12
• /
• 2011

Incidence of Phytophthora blight of hot pepper (Capsicum annuum) and yield (fresh weight) of pepper fruits were investigated at four separate fields located in Cheongwon, Boeun, Eumsung, and Goesan, which are major pepper production areas in Chungcheongbuk-Do. In all of the experimental fields except the Goesan field, increased incidence of Phytophthora blight led to decreased yield of pepper fruits. The harvest time in which the yield of red pepper fruits was highly correlated with the incidence of Phytophthora blight was different between areas: it was highly correlated in the third harvest in Cheongwon (y=-11.0x+435.2, $r^2$=0.99), but in the second harvest in Boeun (y=-15.0x+944.6, $r^2$=0.76). In contrast, there was a very low correlation between the pepper yield and the disease incidence in Goesan in which pepper seedlings grafted on resistant stocks were planted. The final disease incidence in the Cheongwon experimental field reached 100% more than 40 days later in 2007 compared with that in 2006. The control threshold of Phytophthora blight in the pepper fields where disease incidence had been lower than 5% was set as 0.8% disease incidence, which caused less than 5% yield loss.

• Horticultural Science & Technology
• /
• v.28 no.5
• /
• pp.802-809
• /
• 2010

Phytophthora blight of pepper is the most economically important disease in the world cultivation regions. We investigated the phytophthora blight resistance of 300 accessions of Korean landrace of hot pepper germplasms collected from 83 local regions. The disease incidence rate was checked from 7 days to 28 days at an interval of 7 days after inoculation under greenhouse conditions. Among 300 accessions, the disease incidence rate of phytophthora blight of 67 accessions of pepper germplasm was more than 60.1%, while no disease was observed in 37 accessions at 7 days after inoculation. At 28 days after inoculation, five and eleven accessions of pepper germplasm were resistance and moderate resistance to $P.$ $capsici$, respectively. Two hundred forty four susceptible accessions (81.3%) of pepper were scored as having more than 60.1% of disease incidence of phytophthora blight. This result suggests that five candidate pepper germplasm might be used as breeding resources for the phytophthora blight resistance breeding program. Also, further genetic studies should be carried out to verify this result, with the overall focus of providing information on important characteristics of pepper germplasm.

• Current Research on Agriculture and Life Sciences
• /
• v.20
• /
• pp.9-18
• /
• 2002

A total of 31 C. chinense lines selected from 2000 screening were tested again for resistance to P. capsid but resistance was not found in tile lines. A total of 26 selections from Korean land races tested 2001 spring were tested again for resistance to P. capsici, KC180, KC230, KC195 and KC194 showed moderate resistance to P. capsid. However, it was apparent on the basis of horticultural characteristics that KC180 and KC230 had been naturally crossed with AC2258 and CM334, respectively. CM334 and AC2248 seed lots that were increased in different years were taken out and tested for resistance to improve their genetic purity because the resistant genetic resources have been showing some off-types in tile population. Off-types began to be found in 1992 seed lots and tile proportion and degree of tile offs was increasing with time up to 2001. Plants true to the type in 1992 seed lots were selected and their inbred seeds were mass produced in a net cage in the greenhouse. AC2258 included in the experiment together was uniform. In 1995 seed lots of CM334, plants with resistance to P. capsici and low or no number of lateral branching at cotyledonary axil, although they were off from tile original CM334, were found and selection was applied to breed lines fixed in tile characters.

• Journal of Korean Medical classics
• /
• v.18 no.4 s.31
• /
• pp.134-144
• /
• 2005

통과대해역병재${\ulcorner}$동의수세보원(東醫壽世保元)${\lrcorner}$중적상관내용여현대의학적비교연구(中的相關內容與現代醫學的比較硏究), 가류추출여하결론(可類推出如下結論): ${\ulcorner}$내경(內經)${\lrcorner}$중출현적해역병, 재척부혹맥적진단법급자침적류오인식상(在尺部或脈的診斷法及刺針的謬誤認識上), 언급도해역병. 저시인위파열(這是因爲把熱), 혈소(血少), 비토허(脾土虛), 상화작위료기근원적연고(相火作爲了其根源的緣故). 해역병적증상시‘한불한(寒不寒), 열불열(熱不熱), 약불약(弱不弱), 장불장(壯不壯)’급(及)‘소삭, 행산, 불능거(不能去)’ 재(在)${\ulcorner}$동의수세보원(東醫壽世保元)${\lrcorner}$중칭위‘기병가유(其病可愈)’, 이종현대의학적각도진행연구결과(而從現代醫學的角度進行硏究結果), 인위유류사여말초신경적병증(認爲有類似與末稍神經的病證). 종현대의학적원인래간(從現代醫學的原因來看), 유어단백질(由於蛋白質)-능량적영양결핍화유생소급미량원소적부족(能量的營養缺乏和維生素及微量原素的不足), 출현말초신경병증(出現末稍神經病證). 재(在)${\ulcorner}$동의수세보원(東醫壽世保元)${\lrcorner}$적약물중(的藥物中), 야유능량화유생소급미량원소등성분(也有能量和維生素及微量原素等成分), 소이인위대태양인적처방(所以認爲對太陽人的處方), 종영양학각도진행분석연구시유가치적(從營養學角度進行分析硏究是有價値的).

• Research in Plant Disease
• /
• v.16 no.1
• /
• pp.106-108
• /
• 2010

This survey was conducted to investigate effect of covering with polyvinyl ($120{\times}90cm$) on incidence of Phytophthora blight and anthracnose and growth. Early growth of pepper plant was superior when was covered with polyvinyl after planting. Incidence of anthracnose and Phytophthora blight was lower 26.9% and 60.3% in covering system than those in conventional culture system, respectively. A yield of dried red pepper was more 48.5% in cultured with covering system than that in conventional culture system.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.3 no.1
• /
• pp.16-21
• /
• 2001

Regression models were obtained on the base of the correlation between Phytophthora blight incidence in red pepper and the microclimate data obtained from automated weather station (AWS) during 1997 and 1998. A computer program (PEPBLIGHT) was constructed based on the model that the R2 value is highest among regression models. This computer program uses the microclimate data from more than one AWS through the common dialogue box easy and it is able provide disease forecasting information. In addition, it could be applied far other diseases and converts the microclimate data of AWS to the input data for Statical Analysis System (SAS). PEPBLIGHT was first developed for the forecasting computer system of red pepper blight in Korea. PEPBLIGHT is operated on the MS Windows, so that it is easy to use.