• The Plant Pathology Journal
• /
• 제19권3호
• /
• pp.129-132
• /
• 2003

Fusarium wilt of cucumber caused by Fusarium oxy-sporum f. sp. cucumerinum is a serious vascular disease worldwide. Biological control of Fusarium wilt in several crops has been accomplished by introducing non-pathogenic Fusarium sup. and other biocontrol agents in soil or in infection courts. In this study, quantitative models were used to determine the biocontrol efficacy of inundatively applied antagonist formulations and the length of their effectiveness in controlling Fusarium wilt of cucumber. Quantitative model of the form [Y=L (1${-exp}^{-kx}$)] best described the relationship between disease incidence (Y, %) and inoculum density (X) of isolates F51 and F55. Isolate F51 was selected as a more virulent isolate based on the extent of its effectiveness in causing the wilt disease. The degree of disease control (Xi/X) obtained with the density of the biocontrol agent (Z), was described by the model [Xi/X=A (1${-exp}^{-cz}$)]. The zeolite-based antagonist formulation amended with chitosan (ZAC) was better at lower rates of application and peaked at around 5 g/ kg of the potting medium, whereas the peat-based antagonist formulation (PA) peaked at around 10 g/kg of the potting medium. ZAC formulation provided significantly better suppression of Fusarium wilt as described by the curvilinear relationship of the type Y= a+bX+c$X^2$, where Y represents percent disease incidence and X represents sustaining effect of the biocontrol agent.

• The Plant Pathology Journal
• /
• 제21권1호
• /
• pp.68-72
• /
• 2005

The production of antibiotic substances by Serratia plymuthica A21-4 was greatly enhanced by modifying components of a growth medium. When the minimal medium containing $K_2HPO_4$ 0.7%, $KH_2PO_4$ 0.2%, $(NH_4)_2SO_4$ 0.1%, $MgSO_4$ 0.01% was used as basal medium, the best carbon source for antibiotic production was glycerol and the most favorable nitrogen source was ammonium sulfate. The modified medium for antibiotic production also increased colonization ability of A21-4 on pepper root and in the rhizosphere soil. When the cells of A21-4 were suspended in modified medium, the population density of A21-4 on pepper root was 10-100 times higher than that suspended in 0.1 M $MgSO_4$. The population density of A21-4 on root did not decrease under $10^6$ cfu/groot up to 21 days after treatment although the inoculum of A21-4 was reduced to $10^7$ cell/ml. Similar tendency was also observed in the rhizosphere soil. Consequently, Phytophthora blight of pepper was successfully controlled by A21-4 with $10^7$ cell/ml suspended in the modified buffer solution instead of $10^9$ cfu/ml suspended in 0.1 M $MgSO_4$.

• Journal of Microbiology and Biotechnology
• /
• 제13권6호
• /
• pp.881-891
• /
• 2003

Paenibacillus polymyxa is a plant growth-promoting rhizobacterium (PGPR) which can be used for biological control of plant diseases. Several bacterial strains were isolated from rotten roots of Korean ginseng (Panax ginseng C. A. Meyer) that were in storage. These strains were identified as P. polymyxa, based on a RAPD analysis using a P. polymyxa-specific primer, cultural and physiological characteristics, an analysis utilizing the Biolog system, gas chromatography of fatty acid methyl esters (GC-FAME), and the 16S rDNA sequence analysis. These strains were found to cause the rot in stored ginseng roots. Twenty-six P. polymyxa strains, including twenty GBR strains, were phylogenetically classified into two groups according to the ERIC and BOX-PCR analyses and 16S rDNA sequencing, and the resulting groupings systematized to the degrees of virulence of each strain in causing root rot. In particular, highly virulent GBR strains clustered together, and this group may be considered as subspecies or biovar. The virulence of the strains seemed to be related to their starch hydrolysis enzyme activity, but not their cellulase or hemicellulase activity, since strains with reduced or no starch-hydrolytic activity showed little or no virulence. Artificial inoculation of the highly virulent strain GBR-1 onto the root surfaces of Korean ginseng resulted in small brown lesions which were sunken and confined to the outer portion of the root. Ginseng root discs inoculated in vitro or two-year-old roots grown in soil drenched with the inoculum developed significant rot only when the inoculum density was $10^{6}-10^{7}$ or more colony-forming units (CFU) per ml. These results suggest that P. polymyxa might induce ginseng root rot if their population levels are high. Based on these results, it is recommended that the concentration of P. polymyxa should be monitored, when it is used as a biocontrol agent of ginseng, especially in the treatment of stored roots.

• The Plant Pathology Journal
• /
• 제36권4호
• /
• pp.335-345
• /
• 2020

Tomato grey mould has been one of the destructive fungal diseases during tomato production. Ten mM of menadione sodium bisulfite (MSB) was applied to tomato plants for eco-friendly control of the grey mould. MSB-reduced tomato grey mould in the 3rd true leaves was prolonged at least 7 days prior to the fungal inoculation of two inoculum densities (2 × 10⁴ and 2 × 10⁵ conidia/ml) of Botrytis cinerea. Protection efficacy was significantly higher in the leaves inoculated with the lower disease pressure of conidial suspension compared to the higher one. MSB-pretreatment was not effective to arrest oxalic acid-triggered necrosis on tomato leaves. Plant cell death and hydrogen peroxide accumulation were restricted in necrotic lesions of the B. cinereainoculated leaves by the MSB-pretreatment. Decreased conidia number and germ-tube elongation of B. cinerea were found at 10 h, and mycelial growth was also impeded at 24 h on the MSB-pretreated leaves. MSB-mediated disease suppressions were found in cotyledons and different positions (1st to 5th) of true leaves inoculated with the lower conidial suspension, but only 1st to 3rd true leaves showed decreases in lesion sizes by the higher inoculum density. Increasing MSB-pretreatment times more efficiently decreased the lesion size by the higher disease pressure. MSB led to inducible expressions of defence-related genes SlPR1a, SlPR1b, SlPIN2, SlACO1, SlChi3, and SlChi9 in tomato leaves prior to B. cinerea infection. These results suggest that MSB pretreatment can be a promising alternative to chemical fungicides for environment-friendly management of tomato grey mould.

• 한국토양비료학회지
• /
• 제25권1호
• /
• pp.77-88
• /
• 1992

항생제 내성 변이균주 JB7 $nal^rspe^r$와 CB756 $str^rrif^r$을 이용하여 살균하지 않은 밭토양에서 접종방법이 근류균의 증식과 근류형성 및 질소고정에 미치는 영향을 조사하였다. JB7 $nal^rspe^r$균주(菌株)를 종자당 $10^2$에서 $10^8$세포수준으로 접종(接種)했을때 접종농도(接種濃度)의 증가와 함께 근류형성(根瘤形成)이 증가하였다. 접종방법별(接種方法別)로는 YMB배양 액체접종(液體接種)이 Peat slurry나 Peat입자(粒子) 접종(接種)보다 더 많은 근류(根瘤)를 형성(形成)했고, Peat slurry와 입자(粒子) 접종간(接種間)에는 차이가 없었다. 토양(土壤) g당 $10^3$ 세포(細胞)의 근류균(根瘤菌)을 함유(含有)하는 토양(土壤)에 JB7 $nal^rspe^r$와 CB756 $str^rrif^r$을 혼합(混合)하여 접종(接種)했을때 모든 근류(根瘤)가 접종균(接種菌)에 의하여 형성되었으며, JB7 $nal^rspe^r$균주(菌株)에 의한 근류점유율이 월등히 높았다. 품종간에 근류점유율의 차이는 없었다. 접종균류(接種菌株)는 근권에서 점진적으로 증식되었으며, JB7 $nal^rspe^r$가 더 큰 폭으로 증가되었다. 땅콩의 수량은 무접종구보다 접종구가 높았으나 질소처리구(窒素處理區)와 접종구간에는 차이가 없었다.

• 한국작물학회지
• /
• 제32권2호
• /
• pp.173-180
• /
• 1987

본 시험은 참깨 발병(병원균 : Phytophthora nicotianae var. parasitica)에 대한 품종저항성 검정방법 확립을 위해 실시하였다. 공식작물의 묘령, 접종방법, 토양수분상태 및 접종원의 농도는 공시한 중도저항성계통 B-67, IS 103과 나병성계통 수원9호, 수원 2006 모두의 병진전속도와 발병심도에 영향을 주는 것으로 나타났다. 그러나, 파종후 20일된 유묘에 1 $m\ell$당 200개 포자상의 접종원을 폿트(8$\times$16.7$\times$7.2cm)당 10$m\ell$씩 토양표면에 접종한 후 저면관수로 토양수분을 포화상태로 유지하였을 때 계통간 저항성의 차이를 갈 볼 수 있었다. 묘령 70일의 성묘를 사용하였을 때는 토양접종을 하였을 때나 분무접종을 하였을 때 모두 계통간 저항성 차이를 잘 볼 수 있었다. 전술한 유묘검정방법에 의해 이병성계통인 수원2006는 이병주율로는 100%, 발병심도로는 최대치인 9.0을 보였다. 반면에 중도저항성계통인 B- 67은 이병수율로는 20%, 발병심도로는 1.7을 보였다. 발병심도는 0에서 9까지 지수화하여 나타내었다. 예를 들면, 발병심도 0은 병징이 없는 상태, 5는 지면부 줄기가 변색된 경우, 9는 잎마름증상과 함께 줄기변색이 지면부로 부터 10cm 이상인 경우이다. 품종간 저항성의 차이는 병총면적률로도 조사를 하였으며, 이 결과는 발병심도로 조사한 검정결과와 잘 일치하였다.

• 식물병연구
• /
• 제18권2호
• /
• pp.86-92
• /
• 2012

Plasmodiophora brassicae Woron.에 의한 뿌리혹병은 배추과 작물에 발생하는 전 세계적으로 가장 중요한 식물병 중 하나이다. 본 연구는 Brassica oleracea에 속하는 양배추와 브로콜리의 뿌리혹병에 대한 효율적인 저항성 검정 방법을 확립하기 위하여, 레이스 9인 GN1 균주를 이용하여 접종원의 농도와 P. brassicae 접종 후 배양 기간 등의 발병 조건에 따른 양배추와 브로콜리 뿌리혹병 발생을 조사하였다. 접종원의 농도는 14일 재배한 유묘에 포트 당 $2.5{\times}10^9$개의 포자를 접종하는 것이 적당하였으며, 안정적인 발병을 위하여 접종한 유묘는 3일 동안 $20^{\circ}C$ 생육상에서 하루에 12시간 광을 처리하며 배양하고, 그 후 온실($20{\pm}5^{\circ}C$)에서 5주 동안 재배한 후에 발병 정도를 조사하는 것이 요구되었다. 위의 검정법을 이용하여 레이스가 다른 P. brassicae 4개 포장 균주에 대한, 시판 중인 양배추 16종과 브로콜리 17종 품종의 저항성 정도를 실험한 결과, 레이스 9인 GN1, GN2 그리고 GS 균주에 대해서는 중도저항성을 보이는 몇 가지 품종이 있었다. 그러나 레이스 2인 YC 균주에 대해서는 실험한 모든 품종이 고도의 감수성 반응을 나타내었다. 따라서 이 방법은 양배추와 브로콜리 뿌리혹병 저항성을 검정하기 위한 효율적인 검정법이라는 것을 알 수 있었다.

• 한국산림과학회지
• /
• 제101권1호
• /
• pp.77-82
• /
• 2012

표고를 재배하기 위하여 톱밥배지를 $65^{\circ}C$로 저온살균하는 과정은 살균시설비용이 적게들고 배지성분도 보전되는 장점이 있으나, 오염 확률이 높아서 효과는 일정하지가 않았다. 본 연구는 참나무 톱밥배지의 저온살균 후 성공률이 높은 효과적인 배양조건을 알고자 하였다. 참나무톱밥배지를 $65^{\circ}C$, $100^{\circ}C$, $121^{\circ}C$로 살균한 후, 표고톱밥종균을 접종하고 $15^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$에서 배양하거나, 표고종균의 접종간격을 1 cm, 2 cm, 4 cm(표면적 비율은 4%, 11%, 25%)로 하여 표고균사의 생장과 배지의 오염정도를 비교하였다. 저온살균된 배지에서 표고균사생장은 배양온도 $25^{\circ}C$ 이하에서는 $100^{\circ}C$나 $121^{\circ}C$ 살균된 배지에서 처럼 양호하였으나, $30^{\circ}C$ 배양에서는 표고균사생장이 크게 위축되었다. 그리고 저온살균배지에서 표고종균 접종밀도를 1 cm 간격으로 하였을 때에는 배지가 표고균사로 완전점유되었으나, 2~4cm 간격 접종밀도에서는 14~33%의 배지가 오염되었다. 따라서 저온살균배지는 $25^{\circ}C$ 이하에서 25% 이상의 충분한 종균을 접종하여 배양하는 것이 성공적이라고 결론짓는다.

• 한국식물병리학회지
• /
• 제14권4호
• /
• pp.325-330
• /
• 1998

On the basis of the fact that the pycnidiospore of Botryosphaeria dothidea, the causal fungus of apple white rot is a typical water borne spore, a method for quantitative analysis of pycnidiospore dispersal from the warts produced on the diseased apple tree stem was developed. The warts on which cracks developed either on or around them were cut off at the base, and shaked in the water for 4hours at 2$0^{\circ}C$, in which condition the maximum number of spores were released. The volume of shaking solution was calculated as 1 ml per one wart. At the end of shaking, Trio, a household detergent was added to the shaking solution to the concentration of 0.1%, and shaked for additional 10 minutes at 35$^{\circ}C$ to take off the spores attached on the glass ware. One milliliter of the spore suspension thus prepared were passed through transparent membrane filter (pore size : 3.0 ${\mu}{\textrm}{m}$), and the spores attached on the filter were counted under a microscope ($\times$200) after staining them with lactophenol supplemented with aniline blue. The results thus obtained were statistically consistent when at least 30 warts were used simultaneously in single shaking. This method can be applicable in the elucidation of ecology of sporulation and spore dispersal, and also in the screening of the sporulation inhibitor which can be used in the control of the disease by reducing the inoculum density.

• The Plant Pathology Journal
• /
• 제20권4호
• /
• pp.240-243
• /
• 2004

White rot on Allium crops recently had a high incidence with incrensed cultivating areas of tropical garlic types in Korea. Two types of Sclerotium have known as causal agents that produce different size and shapes of sclerotia in infested fields. Therefore, we developed a new method for isolation of sclerotia from infested field soils that can be used for ecological study of Sclerotium spp. and establishment of control strategy. Soil samples collected from heavily infested fields were evenly mixed and placed on a automatic sieve shaker connected with tap water, After 10 min of shaking, residues on 0.5 mm and 0.25 mm sieves were separately collected and suspended with 70% sugar solution, which method floats sclerotia in aqueous layer, Then, floated fraction was carefully separated and mixed with a same volume of 1% sodium hypochlorite solution to differentiate with organic materials. This method provides a direct count of sclerotia under a dissecting microscopy.