Optimum Temperature For Mycelial Growth Research Articles

First Report of Anthracnose Caused by Colletotrichum acutatum on Begonia (Begonia semperflorens Link.) Nurseries

Anthracnose severely occurred on begonia (Begonia semperflorens Link.) nurseries in Gyeongju, Gyeongbuk in July, 2004. More than <TEX>$80\%$</TEX> of begonia seedlings were diseased in the greenhouse surveyed and diseased leaves per plant were <TEX>$12.1\%$</TEX> in average. Yellowish spots occurred on the leaves of begonia as initial symptoms, and they coalesced irregularly to form large brown pleomorphic lesions. Severely infected leaves were defoliated, resulting in abnormal growth of the entire plant. Colletotrichum sp. was repeatedly isolated from the diseased plants and was identified as Colletotrichum acutatum on the basis of the mycological characteristics on potato dextrose agar and RAPD analysis. Pathogenicity of the fungus was also confirmed by artificial inoculation on healthy plants. The optimum temperature for mycelial growth of C. acutatum was around <TEX>$25^{\circ}C$</TEX>. The fungus was sensitive to azoxystrobin, bitertanol, diethofencarb-carbendazim, difenoconazole and tebuconazole. This is the first report on the anthracnose of begonia caused by C. acutatum in Korea.

Sclerotium rolfsii에 의한 비비추 흰비단병

2004과 2005년 7월 경상남도 진주시 칠암동 남강변에 재배중인 비비추에서 S. rolfsii에 의한 흰비단병이 발생되었다. 병징은 잎자루, 줄기, 지제부위가 수침상으로 물러지고 부패하면서 암갈색으로 되고 시들어 말라 죽는다. 병반부와 지제부위의 토양 표면에 흰색의 곰팡이가 솜털처럼 생기고 갈색의 둥근 균핵을 많이 형성되었다. 감자한천 배지에서 갈색의 둥근 균핵을 많이 형성하였으며 크기는 <TEX>$1\~3$</TEX>mm였다. 균사의 폭은 <TEX>$4\~8{\mu}m$</TEX>이며, 균사생육 적온은 <TEX>$30^{\circ}C$</TEX>였다. 균사특유의 clamp connection이 관찰되었다. 비비추에서 발생한 병징과 균학적 특징 및 병원성을 검정한 결과, 이 병을 Sclerotium rolfsii Saccardo에 의한 비비추 흰비단병으로 명명하고자 한다. The stem rot disease was found on Hosta longipes that planted in the flower beds along the Namgang riverside in Jinju city, Korea. The disease occurred first time in July, 2004 and sporadically occurred in 2005. The typical symptom of the disease is water-soaking, dark brown spot on the stem, and getting wilt. The infected plants were mostly died. White mycelial mats were spread over lesions and sclerotia were formed on stems and near soil line. The sclerotia were globoid in shape, <TEX>$1\~3$</TEX> mm in diameter and white to brown in color, The optimum temperature for mycelial growth of the fungus on PDA was <TEX>$30^{\circ}C$</TEX> and the hyphal width was <TEX>$4\~8{\mu}m$</TEX>. Clamp connections were observed in the hyphae of the fungus grown on PDA. Pathogenicity of the causal organism was proved on Hosta longipes according to Koch,s postulate. On the basis of mycological characteristics and pathogenicity to host plants, the fungus was identified as Sclerotium rolfsii Saccardo. This is the first report on the stem rot of H. longipes caused by S. rolfsii in Korea.

Rhizopus stolonifer에 의한 여주 무름병

2003년부터 2005년까지 경남 창원시 대산면 북부마을 여주재배 농가에서 Rhizopus stolonifer에 의한 여주 무름병이 발생하였다. 병징은 처음 과실껍질 부분이 수침상으로 물러지면서 빠르게 부패되었다. 균사생육 적온은 <TEX>$25^{\circ}C$</TEX> 내외로 처음 흰색에서 연한 갈색으로 되며 검은색의 포자낭을 많이 형성한다. 포자낭경은 처음 흰색에서 회색을 나타내며 포자낭을 균사 끝에 형성하고 폭은 <TEX>$15\~30{\mu}m$</TEX> 이었다. 포자낭은 처음에 흰색에서 나중에 검은색으로 되었고 모양은 반구형으로 크기는 <TEX>$90\~180{\mu}m$</TEX>이었다. 주축의 모양은 반구형으로 크기는 <TEX>$80\~150{\mu}m$</TEX>이었다. 포자낭포자는 담갈색으로 단포이며 구형 또는 타원형으로 불규칙한 것이 많으며 크기는 <TEX>$7\~18{\times}6\~12{\mu}m$</TEX>이었다. 이상과 같은 병원균의 균학적 및 병원학적 특성조사 결과로 본 병해를 Rhizopus stolonifer (Ehrenberg ex. Fr.) Lind에 의한 여주 무름병으로 명명할 것을 제안한다. A Rhizopus soft rot caused by Rhizopus stolonifer occurred on Momordica charantia at Daesan-myon, Chang-won city, Gyeongnam province from 2003 to 2005. The disease usually started from wound on fruit with water-soaking lesions. The lesion rapidly expanded and softened. The fungal mycelia grew vigorously and sporangia, sporangiophores, and stolons were formed on surface of the fruit. Spoyangiophores were <TEX>$15\~30{\mu}m$</TEX> in width. Sporangia were globose or hemispheric and <TEX>$90\~180{\mu}m$</TEX> in size. The color of sporangia was white and cottony at first and turned to brownish black with many spores at maturity. Columella were hemispheric and <TEX>$80\~150{\mu}m$</TEX> in size. Sporangiospores were irregular round or oval, brownish-black streaked and <TEX>$7\~18{\times}6\~12{\mu}m$</TEX> in size. The optimum temperature for mycelial growth of the fungus on PDA was <TEX>$25^{\circ}C$</TEX>. On the basis of mycological characteristics and pathogenicity to host plants, the causal fungus was identified as Rhizopus stolonifer (Ehrenberg ex. Fr,) Lind. This is the first report of Rhizopus soft rot on M. charantia caused by R. stolonifer in Korea.

Effects of Curing on Green Mold and Stem-End Rot of Citrus Fruit and Its Potential Application Under Florida Packing System.

The potential of citrus fruit curing for the control of green mold caused by Penicillium digitatum, and the impact of this treatment on stem-end rot caused by Lasiodiplodia theobromae were investigated. The optimum temperatures for mycelial growth of P. digitatum and L. theobromae were about 25 and 30°C, respectively. P. digitatum did not grow at 35°C, while L. theobromae did. Injuries of 'Valencia' oranges developed less green mold disease at 30 and 35°C than at 25°C or lower. Green mold incidences on 'Valencia' oranges treated at 21°C (uncured control), 30 and 35°C for 48 h were 51, 17.4, and 0%, respectively, for inoculated fruit, and 18.8, 11.4, and 0%, respectively, for wounded fruit after 2 weeks of storage at 21°C. However, a significant increase in stem-end rot occurred at 35°C when compared with 21°C (uncured control). In two of three different tests, curing fruit at 35°C for 48 h achieved better green mold control than a shorter curing time of 24 h. Curing 'Pineapple' oranges showed a similar or better efficacy for green mold control than imazalil at 500 and 1,000 ppm applied by either dip or packingline drip. The combination of thiabendazole drench (500 ppm) and curing of wounded 'Valencia' oranges and inoculated 'Flame' grapefruit reduced both green mold and stem-end rot by more than 93%. This study suggests that curing (35°C for 48 h) could be integrated into the current Florida citrus packing system to effectively control postharvest decays.

Stem Rot of Tawny Daylily (Hemerocallis fulva) Caused by Sclerotium rolfsii in Korea

In July 2002, a destructive stem rot of tawny daylily (Hemerocallis fulva) was occurred sporadically in exhibition farm of Gyeongsangnam-do Agricultural Research and Extension Services located in Hamyang-gun, Korea. The fungus also caused collar and crown rot, and systemic wilt or blight of whole plant. White mycelium spread over stems and petioles of infected plants and sclerotia were formed on the old lesions and near the soil surface. The optimum temperature for mycelial growth and sclerotial formations was 30°C on PDA. The mycelial width ranged 4.2~10.4 μm and the color was white, usually many narrow mycelial strand grew in the aerial mycelium and formed clamp connection. The shape of sclerotia was spherical and 1.0~3.2 mm in diameter. The fungus was isolated repeatedly from the infected tissues and confirmed its pathogenicity to Hemerocallis fulva and identified as Sclerotium rolfsii. This is the first report on the stem rot of H. fulva caused by S. rolfsii in Korea.

후숙 온도가 참다래 저장병 발병에 미치는 영향

This study was conducted to identify optimum ripening condition for kiwifruits (Actinidia deliciosa) to prevent postharvest fruit rots caused by Botryosphaeria dothidea, Diaporthe actinidiae and Botrytis cinerea. The optimum temperatures for mycelial growth of B. dothidea, D. actinidiae and B. cinerea were , and , respectively, and the incidence was closely related with the temperature. Although kiwifruits ripened faster at higher temperatures, the rates of diseased fruits increased with the rates of ripened fruits increased. Optimum conditions for ripening of kiwifruit were 20-day at 17C.

Sooty Mold of Persimmon (Diospyros kaki) Caused by Cladosporium cladosporioides

【In 2002, sooty mold was observed on persimmon (Diopyros kald) from the Jinju Agricultural Products Wholesale Market in Gyeongnam, Korea. The lesion of the sooty mold usually appeared as scars or wounds formed on the surface of the fruits. The symptom started with water soaking lesion, then the fruit softened rapidly. Colony of the causal pathogenic fungus was dark green in color on potato dextrose agar. The diameter of growing hyphae was 1-2 $\mu\textrm{m}$ . The mostly one-celled conidia were ovoid, lemon or cylinder in shape, blastophores, and sized 46-132 $\mu\textrm{m}$ . Erected conidiophores were long-branched chains and their lengths varied from 24 to 346 $\mu\textrm{m}$ with 2-5 $\mu\textrm{m}$ width. The optimum temperature for mycelial growth was about 2 $0^{\circ}C$ . Based on their mycological characteristics, the fungus was identified as Cladosporium cladosporioides. This is the first report in Korea of the sooty mold of persimmon caused by the said fungus.】

고추 갈색점무늬병원균 (Cercospora capsici)의 배양특성과 다량 포자형성법

High sporulation method and cultural characteristics of Cercospora capsici causing Cercospora leaf spot of pepper were examined. Optimum temperature for mycelial growth of Cercospora capsici was . The fungus did not grow below and over . Optimum pH for mycelial growth was pH 4.0~pH 8.0. Mycelial growth was not influenced by light. C. capsici sporulated well on pepper leaf agar (5g/l). A standard method of sporulation established was as follows. The mycelial plugs were ground with some water in motar with pestle. The mycelial suspension was smeared on the surface of medium and incubated for 2~3 days at . The culture surface was lightly scraped with a brush after adding 1 ml of sterile water to stimulate sporulation and further incubated for 2~3 days.

제주지역 감자더뎅이병 발생 특성

제주지역 감자재배포장에서 문제가 되고 있는 더뎅이 병의 방제대책 마련을 위해 1995년부터 1999년까지 더뎅이병의 발생 특성에 관한 연구를 실시한 결과 감자재배 기간이 오랠수록 더뎅이병 이병율은 증가하였고, 토양 pH가 높아질수록 발병이 증가하는 경향이었으며, 감자 연작포장의 더뎅이병 발생율이 54.8% 인데 비해, 감자 재배 전 보리 혹은 배추를 재배하거나 휴경을 한 포장에서는 더뎅이병 발생율이 20.8~26.3%로 비교적 낮았다. 분리한 균주에서 Stteptomyces scabies, S. turgidiscabies, S. acidiscabies가 동정되었으며, 이들 균의 분리 비율은 각각 37.7%, 14.8%, 18.0%였다. 더뎅이병원균의 균사생육 최적온도는 <TEX>$28~30^{\circ}C$</TEX> 였으며, 최적 pH는 6~7이었다. This study was conducted to clarify developmental characteristics of scab in potato fields in Jeju island, Korea from 1995 to 1999. Occurrence of potato scab increased with repeated cultivaton of potato and high soil pH in the fields. Incidence of the disease was high as 54.8％ in the repeatedly cultivated potato fields but relatively low as 20.8~26.3% in the non-cultivated fields and in the fields where barley and Chinese cabbage were formerly cultivated. A total of 66 isolates were obtained from the diseased patato tubers and identified as Streptomyces scabies, S.turgidiscabies and S. acidiscabies. The isolation frequency of each Streptomyces species was 37.7%, 14.8% and 18.0%, respectively. The optimum temperature for mycelial growth of the Streptomyces spp. was <TEX>$28~30^{\circ}C$</TEX>, and the optimum pH for that 6~7.

Sclerotinia sclerotiorum에 의한 미나리 균핵병

2002년 12월 경상남도 의령군 가례면 비닐하우스 밭미나리 재배포장에서 미나리 잎과 줄기부분이 수침상으로 물러지고 썩으면서 그 부위에 흰색 곰팡이와 균핵이 발생하는 이상증상이 발생했다. 균총은 무색에서 흰색을 띠면서 초코렛색으로 된다. 균핵은 병반부와 PDA 배지 모두 검은색의 구형, 타원형 또는 불규칙한 모양이었으며, 크기는 1.0~10.7 <TEX>${\times}$</TEX>1.0~7.6 mm 이었다. 자낭반은 컵모양으로 크기는 0.4~1.6cm이었다. 자낭은 원통형으로 자낭안에 자낭포자가 8개 들어있으며, 크기는 74~236 <TEX>${\times}$</TEX>4.2~24.8 <TEX>$\mu\textrm{m}$</TEX> 이었다. 자낭포자는 타원형으로 단세포이며 무색이다. 크기는 8.3~<TEX>$12.4{\times}3.6$</TEX>~7.2 <TEX>$\mu\textrm{m}$</TEX> 이었다. 균사생육 최적온도는 <TEX>$25^{\circ}C$</TEX>이며, 균핵형성 최적온도는 15~<TEX>$20^{\circ}C$</TEX>이었다. 이상과 같이 병원균의 균학적 특징 및 병원성을 검정한 결과, 이병을 Sclerotinia sclerotiorum에 의한 미나리 균핵병으로 명명할 것을 제안하였다. A sclerotinia rot of Water cress (Oenanthe javanica) occurred in the commerical farmers field at Garye-myon, Uiryeong-gun, Gyeongnam Province, Korea, 2002. The typical symptoms appeared on leaves and stems. At first, the infected leaves or stems turned dark green later become watery soft rotted; white fluffy mycelia grew from the lesion, later formed black sclerotia. Sclerotia on the infected plants and PDA medium were globose to cylindrical or irregular in shape and 1.0~10.7 <TEX>${\times}$</TEX>1.0~7.6 mm in size. Cup-shaped aphothecia with numerous asci were formed from sclerotinia and the size were 0.4~1.6 cm in diameter. Asci with 8 spores were cylindrical and 74~236 <TEX>${\times}$</TEX> 4.2~24.8 m in size. Ascospores of one cell were hyaline, ellipsoid to ovoid in shape, and 8.3~12.4 <TEX>${\times}$</TEX> 3.6~7.2 m in size. The optimum temperature for mycelial growth was <TEX>$25^{\circ}C$</TEX> , and sclerotinia forma-tion was between 15~<TEX>$20^{\circ}C$</TEX>. On the basis of mycological characteristics and pathogenecity test to host plants, the fungus was identified as Sclerotinia sclerotiorum. This is the first report of Sclerotinia sclerotiorum caused sclerotinia rot on Oenanthe javanica caused by in Korea.

Corky Root of Tomato Caused by Pyrenochaeta lycopersici in Korea

Corky root symptoms caused by Pyrenochaeta lycopersici were observed on the roots and stem base of tomato plants in Korea. Symptoms on infected plants typically appeared as stunting and generally lacking vigor, and infected plants die back from the foliage tips after fruits have set. Brown lesions appearing with bands around the roots were characteristic symptoms of the disease. The lesions become swollen and cracked along the length of the root with corky appearance. Based on cultural and morphological characteristics, the fungus from the diseased plants was identified as Pyrenochaeta lycopersici. Pycnidia were solitary, globose to subglobose, brown to black, darker around the neck region, and measured 173-215 in diameter with septate setae up to 102-1326.5 . Conidia were hyaline, unicellular, and 4.2-4.7l.5-2.0 long. Optimum temperature for mycelial growth of the p. lycopersici isolates ranged from to . Fifteen isolates off lycopersici were tested for pathogenicity to susceptible and tolerant cultivars of tomato plants by artificial inoculation. Three isolates of P. lycopersici induced typical corky root discoloration on susceptible tomato cultivars but not on tolerant tomato. This is the Erst report in Korea of tomato corky root disease caused by P. lycopersici.

Screening of Urdbean (Vigna mungo L.) Germplasm for Resistance to Charcoal Rot Disease

Each of 48 monoconidial isolates of Colletotrichum gloeosporioides Penz. obtained from diseased fruits of pepper was classified into strain G or strain R based upon pathogenicity to green and red fruits, morphology of conidia, and cultural characteristics in potato dextrose agar. The strain G was designated for isolates to cause anthracnose symptoms both on green and red fruits. All isolates of the strain G produced conidia abundantly. but produced no perithecia and setae in PDA. Conidia of all isolates in the strain G were attenuated or round at one end. The optimum temperature for mycelial growth of strain G was . The mycelia of strain G in PDA appeared to be whitish when young, and turned to be dark in old culture. Symptoms on pepper fruits caused by the strain G were somewhat sunken to be circular to elliptical lesions. Yellowish conidial masse were observed at the center of lesions, and the lesions turned to irregular shape and to reddish brown color in the later stage of disease development. No setae were visible on the acervuli. The strain R was designated for isolates to cause anthracnose symptoms only on red fruits of pepper. All isolates of the strain R produce conidia, and perithecia of Glomerella cingulata (Stonem.) Spauld. & v. Sch. in PDA. Some isolates of the strain R produced setae in culture under fluorescent light. Conidia of all isolates in the strain R were round and blunt at the ends. The optimum temperature for mycelial growth of strain R was the same as that of strain G. The mycelial growth of strain R was faster than that of strain G in PDA. The mycelia of strain R in PDA appeared to be gray to dark. Symptoms on pepper fruits caused by the strain R were circular to irregular black ring-spots Short setae or no setae were visible on the acervuli.

Coniella granati에 의한 석류 열매썩음병

2002년 7월 경남 통영시 광도면 석류재배 농가포장에서 열매가 부패되는 이상증상이 발생하였다. 분리된 병원균은 감자한천배지에서 균총의 색깔은 흰색이며 물결모양을 이루면서 왕성하게 자랐고, 배지상에서 분생포자각을 잘 형성하였다. 분생포자는 단세포이며 모양은 방추형이고, 색깔은 갈색 또는 올리브색이다. 크기는 10.3~17.4<TEX>$\times$</TEX>2.8~4.0 <TEX>$\mu\textrm{m}$</TEX> 였다. 분생포자 형성 세포는 짧은 원통형이며 무색으로 크기는 12.4~1.4<TEX>$\times$</TEX>2.8~3.6 <TEX>$\mu\textrm{m}$</TEX> 였다. 불생포자각의 모양은 구형이며 갈색으로, 각벽은 2~3세포이고, 크기는 124.6~228.4 <TEX>$\mu\textrm{m}$</TEX> 였다. 균사생육 적온은 <TEX>$25^{\circ}C$</TEX>였다. 분리된 병원균을 건전한 석류에 유상, 무상접종한 결과 접종 3일 후 감염을 일으켰으며, 병원성이 강하였다. 이상과 같이 이 병원균을 Coniella granati에 의한 석류열매 썩음병으로 명명할 것을 제안한다. Fruit rot of pomegranate (Punica granatum) caused by Coniella granati were observed in several farmer's fields in Gwangdo-myon, Tongyeong City, Gyeongnam Province, Korea. The symptoms occurred on fruit with rotting then eventually dropping and mummification. The colony color of causal fungus was whitish on potato dextrose agar. Conidia were single celled, pale brown or olive in color at maturity, straight or slightly curved fusiform in shape, and were 10.3~17.4<TEX>$\times$</TEX>2.8~4.0 <TEX>${\mu}{\textrm}{m}$</TEX> in size. Conidiogenous cell were hyaline, branched only at the base aseptate, elongate, phialidic, enteroblastic and 12.4~1.4<TEX>$\times$</TEX>2.8~3.6 <TEX>${\mu}{\textrm}{m}$</TEX> in size. Pycnidia were black in color and globose in shape and 124.6~228.4 <TEX>${\mu}{\textrm}{m}$</TEX> in size. Optimum temperature for mycelial growth was <TEX>$25^{\circ}C$</TEX>. On the basis of mycological characteristics and pathogenecity test on host plants, the fungus was identified as Coniella granati. This is the first report on the fruit rot of pomegranate caused by Coniella granati in Korea.

Effect of environmental factors on growth, pycnidial production and spore germination of Microsphaeropsis isolates with biocontrol potential against apple scab

The potential as biocontrol agents of the apple scab pathogen, Venturia inaequalis and the effect of environmental factors on growth, pycnidial production and spore germination of four isolates of Microsphaeropsis were examined on culture media and leaf discs. V. inaequalis ascospore production was reduced by 52, 77, 89 and 95% on leaf discs treated with the isolates IMI 294735, P176A, DAOM 198536 and P130A, respectively. For all isolates, optimum temperature for mycelial growth was 25 °C. More pycnidia were produced on culture media than on leaf discs. On culture media, optimum temperature was from 15 to 25 °, while on leaf discs it varied among isolates. Pycnidial production was inhibited by darkness and a minimum of 8 h light d −1 was required. Spores of isolates P130A and DAOM 198536 germinated at temperatures above 15 ° and at pH 4–5, as compared to 10 ° and pH 4–8 for isolates P176A and IMI 294735. The best candidates were P130A and DAOM 198536 and optimum conditions for growth, pycnidial production and spore germination were temperatures between 20 and 25 °, pH approx. 4 and light.

Pseudocercospora dendrobii에 의한 덴드로비움 검은잎마름병

Sooty leaf blight was found on Dendrobium sp. in several farmers` fields located in Namji-eup, Changnyeong-gun, Gyeongnam province, Korea in 2001. Symptoms of the disease appeared on leaves. Sooty leaf spots were started with amphigenous, subeircular to irregular spots, with light grayish brown to black color with definite margin lines on the upper surface of leaves. Infected leaves became defoliated and whole plants eventually were died. The infection rates of the disease in the surveyed area reached up to 64.8%, in the early September. Conidiophores of the causal fungus were dark grayish brown in color, densely fasciculate, straight, curved to sinuous, branched, septate and in size. Conidia were pale to olivaceous in color, obclavatecylindric, straight to slightly curved in shape, septate and in size. The optimum temperature for mycelial growth of the fungus was . The fungus was identified as Pseudocercospora dendrobii on the basis of its mycological characteristics. This is the first report on sooty leaf light of Dendrobium sp. caused by Pseudocercospora dendrobii in Korea.

느타리버섯 유해균 Hypocrea sp.의 형태 및 URP-PCR 분석

느타리버섯 균상에 발생하는 Hypocrea속 균의 분류학적 위치를 확립하기 위하여 유성세대 및 무성세대의 형태적 특징을 조사하였고, 국내 분리 균주의 RAPD, RFLP, URP-PCR 분석 등 분자생물학적 특징을 조사하였다. 1. 충남과 전남 일대의 8개 시, 군의 느타리 재배사에서 19 균주를 분리하였으며 이들 균주간의 형태적, 발생생태학적 변이는 없었고, 기존 보고된 Hypocrea 종들과는 다른 형태적 특징을 나타내었다. 2. Hypocrea 자좌의 크기는 <TEX>$6.0{\sim}13.0{\times}3.0{\sim}11.0mm$</TEX>이었고, 위유조직으로 구성되어 있으며 대부분 군생하고 처음엔 백색이지만 성숙되면 노란빛을 띤 갈색을 나타내었다. 자낭각은 구형으로 크기가 평균 <TEX>$239.9{\times}204.1{\mu}m$</TEX>이었으며, 자낭에는 16개의 자낭포자(part ascospores)를 형성하였고, 자낭과 장낭포자의 크기는 각각 <TEX>$103.3{\times}4.9{\mu}m$</TEX>와 <TEX>$6.5{\times}4.7{\mu}m$</TEX>이었다. 3. 무성세대의 phialide는 보통 Trichoderma virens와 유사한 형태로 모여서 형성되나 때때로 penicillate의 형태도 관찰되었다. T. virens형 phialide의 크기는 <TEX>$10.8{\times}3.5{\mu}m$</TEX>이었고 penicilliale형은 <TEX>$14.7{\times}3.4{\mu}m$</TEX>이었다. 분생포자는 계란형에서 타원형으로 표면은 매끈하고 크기는 <TEX>$4.5{\times}2.9{\mu}m$</TEX>이었다. 4. Hypocrea 균주들의 배양적 특징 조사한 결과, PDA 배지에서 균사생장 최적 온도는 <TEX>$25^{\circ}C$</TEX>이었고 자좌는 <TEX>$15{\sim}25^{\circ}C$</TEX> 범위에서 발생하였으며 자좌 발생 최적 온도는 <TEX>$20^{\circ}C$</TEX>였다. 5. RAPD 및 RFLP 분석을 실시한 결과 Hypocrea속 균은 공시균주는 모두 단일 유전 개체군으로 느타리 재배사에서 발생하는 Trichoderma속 균 및 기존에 보고된 Hypocrea spp.와는 다른 분류군으로 나타났다. Recently a serious outbreak of weed mould caused by a species of Hypocrea occurred in oyster mushroom (Pleurotus ostreatus) substrates in Korea. The disease was characterized by a rapid infestation of the oyster mushroom substrates by Hypocrea sp. and subsequent inhibition of fructification of the mushroom. In spite of it's serious losses to the oyster mushroom industry in Korea, etiology and ecology of the disease have not been studied. Morphological characteristics of the fungus were examined and molecular characteristics of the fungus were compared with those of the green moulds (Trichoderma spp.) isolated from oyster mushroom bed. Stromata formed superficially on suface of the substrates were pulvinate to effuse or irreguler, initially white but becoming yellowish brown, measuring <TEX>$6.0{\sim}13.0{\times}3.0{\sim}11.0mm$</TEX>. Perithecia were globose to subglobose, immersed in stroma, <TEX>$223{\sim}263\;(Ave.239.9){\times}167.3{\sim}231\;(Ave.204.1){\mu}m$</TEX> in size. Asci were unitunicate, cylindrical, nonamyloid, <TEX>$82.7{\sim}124.8\;(Ave.103.3){\times}4.1{\sim}5.1\;(Ave.4.9){\mu}m$</TEX> in size, 16 part-spored. Ascospores were bullet-shaped or somewhat oblong, hyaline, bicellular, roughened or warted, <TEX>$5.4{\sim}7.4\;(Ave.6.5){\times}3.6{\sim}5.5\;(Ave.4.7){\mu}m$</TEX> in size. This fungus readily form the stroma on PDA. Mycelia on PDA nearly invisible and without cottony aerial mycelium. Optimum temperature for mycelial growth of this fungus was <TEX>$25^{\circ}C$</TEX> on PDA and its growth rate was 15 mm per day. This species did not grow at below 10 and above <TEX>$35^{\circ}C$</TEX>. Phialides in culture enlarged in the middle and aggregated to penicillate type. They were very variable, shorted ampulliform and occasionally curved when matured, but cylinderical when young, measuring <TEX>$11.9{\sim}24.3\;(Ave.\;14.7){\times}2.9{\sim}3.9\;(Ave.\;3.4){\mu}m$</TEX> when matured and <TEX>$7.2{\sim}14.0\;(Ave.\;10.8){\times}2.8{\sim}4.9\;(Ave.\;3.5){\mu}m$</TEX> when young. Phialosopres were ovoid to ellipsoid, smooth, measuring <TEX>$3.5{\sim}7.2\;(Ave.\;4.5){\times}2.6{\sim}3.3\;(Ave.\;2.9){\mu}m$</TEX>. Nineteen isolates of Hypocrea sp. were analyzed on the basis of molecular characteristics and classified into phenotypic groups. On the basis of RAPD, URP-PCR, the fungus was confirm to monoclonal, and was classified as a different taxon from reported species of Hypocrea and Trichoderma and supposed to be a new species not previously reported in literature.

Rhizopus stolonifer에 의한 감귤 무름병

2002년 진주시 농산물 도매시장에서 Rhizopus stolonifer에 의한 감귤 무름병이 발생하였다. 병징은 처음 과일 껍질 부분이 수침상으로 물러지면서 급속히 진전되어 썩었다. 균사는 처음 흰색에서 연한 갈색으로 되며 검은색의 포자낭을 형성한다. 포자낭병은 처음 무색에서 회색을 나타내며 포자낭을 끝에 만들고 길이는 <TEX>$900{\sim}4300{\mu}m$</TEX>였다. 포자낭은 처음에 무색에서 나중에 검은색이고 아구형으로 크기는 <TEX>$98{\sim}346{\mu}m$</TEX>이다. 추축은 아구형 또는 타원형으로 직경은 <TEX>$60{\sim}216{\times}72{\sim}143{\mu}m$</TEX>이다. 포자낭포자는 담갈색으로 단포이며 구형 또는 타원형으로 크기는 <TEX>$8{\sim}18.3{\mu}m$</TEX>였다. 균사생육 적온은 <TEX>$25^{\circ}C$</TEX>였다. 이상과 같이 병원균의 균학적 특징과 병원성을 검정한 결과 이병을 R. stolonifer에 의한 감귤 무름병으로 명명할 것을 제안하고자 한다. A fruits soft rot caused by Rhizopus stolonifer found on citrus fruit in Jinjn City Agricultural Products Wholesale Market. The disease infection usually started from wounding. At first, the lesions started water soaked and rapidly softened and diseased lesion gradually expanded to other fruits in the same container. The mycelia grew vigorously on the surface of fruits and formed sporangia, sporangiophores and stolons. Sporangiophores were <TEX>$900{\sim}4300{\mu}m$</TEX> in size. Sporangia were globose or subglobose and <TEX>$98{\times}346{\mu}m$</TEX> in size. The color of sporangia was white at first and then turned black with many spores. Columella were globose or ellipsoid and <TEX>$60{\sim}216{\times}72{\sim}143{\mu}m$</TEX> in size. Sporangiospores were globose or ellipsoid, brownish-black streaked and <TEX>$8{\sim}18.3{\mu}m$</TEX> in diameter. Zygospores were globose, black and <TEX>$98{\sim}176{\mu}m$</TEX> in size. The optimum temperature for mycelial growth of the fungus on PDA was <TEX>$25^{\circ}C$</TEX>. The causal fungus was identified as Rhizopus stolonifer. This is the first report of rhizopus soft rot on citrus fruit caused by R. stolonifer in Korea.

Effect of soil temperature on disease development in melon plants infected by Monosporascus cannonballus

The effect of soil temperature on melon collapse induced by Monosporascus cannonballus was studied in the laboratory and in the field. In the laboratory, ascospore germination and hyphal penetration into melon roots were enhanced by increasing the temperature from 20 to 32°C. The optimum temperature for mycelial growth of five isolates of M. cannonballus was 30°C. In the field, the effect of temperature was studied in experiments conducted during the winter and autumn cropping seasons from 1995 to 1998. Disease progress was much faster in the autumn than in the winter crop seasons. Disease incidence reached 100% in the three consecutive autumn seasons studied. In the winter seasons, however, planting date influenced disease incidence. Early planting, at the beginning of January, resulted in a low disease incidence (6–26%, 125 days after planting), whereas planting at the end of January resulted in higher disease incidence (72–88%, 95–119 days after planting). In plots in which the soil was artificially heated to 35°C during the winter season, disease incidence reached 85%, as in the autumn season. Plants grown during the winter in unheated soil, or in artificially heated soil disinfected with methyl bromide, did not collapse. Root colonization by the pathogen was higher in the autumn and in heated soil than in the winter season in nonheated soil. Fifty per cent of root segments were colonized 35, 42 and 67 days after planting in the winter‐heated, autumn and winter‐unheated plots, respectively. A high correlation was found between soil temperatures above 20°C during the first 30 days after planting and disease severity. It is suggested that soil temperature during the early stages of plant development is an important factor in disease development and the expression of melon collapse caused by M. cannonballus.

Isolation and Identification of Colletorichum musae from Imported Bananas

Colletotrichum musae was isolated from dark-brown anthracnose lesions on commercial banana (Musa sapientum L.) to establish the causal agent of the symptom. The fungus grew fast and produced white aerial mycelium on PDA. Acervuli developed abundantly on culture plates after incubation for 10 days at <TEX>$25^{\circ}C$</TEX>. Pinkish conidial masses were produced on the acervuli, which mostly coalesced together, Conidia were aseptate, hyaline, straight, ellipsoid to globose, and 14.5<TEX>$\times$</TEX>6.9 <TEX>$\mu\textrm{m}$</TEX> in size. Black, clavate, round, or irregular-shaped appressoria measuring 8.8<TEX>$\times$</TEX>6.8 <TEX>$\mu\textrm{m}$</TEX> were readily formed from germ tubes. Setae-like structures were not found either on the lesion or on the cultures. Sclerotia were also absent. Among the media, PDA medium was the best for mycelial growth. The optimum temperature for mycelial growth was <TEX>$28^{\circ}C$</TEX>, while the optimum pH ranged from pH 5.5 to 6.5. The isolates of C musae caused black necrotic lesions on banana fruits by needle-wound inoculation, and orange-colored spore masses were produced on the lesions. The fungus also caused discoloration on apple fruits inoculated.

Occurrence of Strawberry Scab Caused by Cladosporium herbarum in Korea

A black scab was observed on strawberry (Fragaria ananasso) in plastic film houses around Jinju area during the winter of 2000. The disease started from leaves then moved to calyx and runner. At the beginning, the infected area started with small dark brown spots then gradually expanded. The pathogenic fungus was purely isolated from the diseased leaves, calyx and runner. The fungus was inoculated to test Koch’s postulates and proved to be the causal agent of the disease. The isolated fungus grew readily on potato dextrose agar, forming dark green to dark gray colonies. The optimum temperature for mycelial growth was about 25°C. The diameter of growing hyphae was 3.8~5.6 μm. Conidia were ellipsoidal, ovoid or subspherical, mostly one-celled but occasionally septate. The size of conidia were 4.1~11.7×3.8~5.3 1-cell, 9.3~ 18.8×4.0~7.4 μm 2-cell and formed in long branched chains on the erected conidiophores which were dark brown and variable in length between 28.8~236.2×3.0~6.2 μm in size. The fungus was identified as Cladosporium herbarum on the basis of its morphological characteristics. The black scab disease of strawberry caused by C. herbarum has not been reported in Korea previously.