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Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

Colletotrichum panacicola isolates were obtained from anthracnose lesions of Korean ginseng and compared with four Colletotrichum species in morphology, molecular phylogeny and pathogenicity. Based on morphological characteristics, C. panacicola was easily distinguished from Colletotrichum gloeosporioides but not from Colletotrichum higginsianum, Colletotrichum destructivum and Colletotrichum coccodes. A phylogenetic tree generated from ribosomal DNA-internal transcribed spacer sequences revealed that C. panacicola is remarkably distinguished from C. gloeosporioides and C. coccodes but not from C. higginsianum and C. destructivum. However, molecular sequence analysis of three combined genes (actin + elongation factor-1α + glutamine synthatase) provided sufficient variability to distinguish C. panacicola from other Colletotrichum species. Pathogencity tests showed that C. panacicola is pathogenic to Korean ginseng but not to other plants. These results suggest that C. panacicola is an independent taxon distin-zguishable from C. gloeosporioides and other morphologically similar Colletotrichum species.

Stem canker symptoms were observed in a rape field in Muan, Korea during a disease survey in May 2006. A total of 15 isolates of Phoma sp. were obtained from the infected stems of the plant. All isolates were identified as Leptosphaeria biglobosa based on their morphological and cultural characteristics. The Korean isolates of L. biglobosa were assigned to `brassicae` among six subclades of L. biglobosa complex based on the entire ITS sequences of rDNA. Pathogenicity of the fungal isolates was confirmed on leaves and stems of rape by artificial inoculation. This is the first report that Leptosphaeria biglobosa causes stem canker of rape in Korea.

Bacterial wilt, Fusarium wilt and Foot rot caused by Ralstonia solanacearum, Fusarium oxysporum, and Phytophthora capsici respectively, continue to be severe problems to tomato, potato and black pepper growers in Vietnam. Three bio-products, Bacillus vallismortis EXTN-1 (EXTN-1), Bacillus sp. and Paenibacillus sp. (ESSC) and Bacillus substilis (MFMF) were examined in greenhouse bioassay for the ability to reduce bacterial wilt, fusarium wilt and foot rot disease severity. While these bio-products significantly reduced disease severities, EXTN-1 was the most effective, providing a mean level of disease reduction 80.0 to 90.0% against bacterial wilt, fusarium wilt and foot rot diseases under greenhouse conditions. ESSC and MFMF also significantly reduced fusarium wilt, bacterial wilt and foot rot severity under greenhouse conditions. Bio-product, EXTN-1 with the greatest efficacy under greenhouse condition was tested for the ability to reduce bacterial wilt, fusarium wilt and foot rot under field condition at Song Phuong and Thuong Tin locations in Ha Tay province, Vietnam. Under field condition, EXTN-1 provided a mean level of disease reduction more than 45.0% against all three diseases compared to water treated control. Besides, EXTN-1 treatment increased the yield in tomato fruits 17.3% than water treated control plants.

Twenty isolates of Bacillus spp. obtained from livestock manure composts and cotton-waste composts were tested for in vitro antagonistic effects against soilborne plant pathogenic fungi, Fusarium oxysporum, Phytophthora capsici, Rhizoctonia solani AG-4, and Sclerotinia sclerotiorum. Seven isolates of Bacillus spp. had antagonistic effects on mycelial growth of all the isolates of F. oxysporum tested. The bacterial isolate RM43 was the most effective to inhibit the mycelial growth of the fungal isolates. Twelve isolates of Bacillus spp. had antagonistic effects on mycelial growth of all the isolates of P. capsici tested. The bacterial isolates M34 and M47 were very effective to inhibit the mycelial growth of the fungal isolates. Thirteen isolates of Bacillus spp. had antagonistic effects on mycelial growth of all the isolates of R. solani AG-4 tested. The bacterial isolates M27 and M75 were very effective to inhibit the mycelial growth of the fungal isolates. Fourteen isolates of Bacillus sp. had antagonistic effects on mycelial growth of all the isolates of S. sclerotiorum tested. The bacterial isolates M49 and M75 were very effective to inhibit the mycelial growth of the fungal isolates. The antagonistic effects of most Bacillus spp. isolates against the isolates of the four fungi differed depending on the fungal species and the isolates of each fungus. The bacterial isolates M27 and M75 were the most effective to inhibit the mycelial growth of all four fungi.

【Biocontrol activity of five strains of selected rhizo-bacteria were tested in tomato against bacterial wilt caused by Ralstonia solanacearum. After root bacterization the plants were grown in a perlite-hydroponic system. Upon challenge inoculation with the pathogen, all of the rhizobacterial strains efficiently suppressed the bacterial wilt in tomato in various rates, at maximum by the strain, Bacillus vallismortis strain EXTN-1. While the percent of infected plants in the non-bacterized control plants were 95%, it was only 65% in plants pre-treated with EXTN-1. It was also demonstrated that the movement of R. solanacearum within the stem was significantly hampered when the plants were root bacterized. As EXTN-1 has no antagonistic properties against R. solanacearum, the bacterial wilt was probably suppressed by a mechanism other than antibiosis. Previously, the strain had been proven to produce an efficient elicitor for inducing systemic resistance in many crops. As the present study confirmed that EXTN-1 has the ability for reducing the pathogen spread in tomato, the strain could be effectively used as a potential biocontrol agent against bacterial wilt.】

Four leguminous crops grown in greenhouses and fields in Korea were surveyed from 2000 through 2002. Sclerotinia rot most severely occurred up to in Phaseolus vulgaris grown in greenhouses but occurred as low as in that grown in fields. Incidence of the disease in Pisum sativum grown in greenhouses ranged , and that in Vicia Java and Vigna sinensis grown in fields was and , respectively. Symptoms of Sclerotinia rot commonly developed on stems and pods of the crops. A total of 59 isolates of Sclerotinia species were obtained from diseased stems and pods of the crops. All of the isolates were identified as Sclerotinia sclerotiorum based on their morphological characteristics. Eight isolates of the fungus were tested for their pathogenicity to four host crops by artificial inoculation. All of the isolates induced rot symptoms on stems of the host crops tested, which were similar to those observed in the fields. The pathogenicity tests revealed that there was no significant difference in the susceptibility to the isolates among the leguminous crops tested This is the first formal report that S. sclerotiorum causes the Sclerotinia` rot of the four leguminous crops in Korea.

Soft rot occurred severely in onion bulbs stored under low temperature () in storage houses at Changyoung, Kyungnam province, Korea in early 2000. Water-soaking and yellowish-brown lesions initially appeared on the outside scales of diseased onion bulbs, gradually progressing into the inside scales. Among the bacterial isolates obtained from the lesions, K-2 isolate was found to be responsible for the disease, which grew at a temperature range of from to with optimum temperature of -. However, it showed strong pathogenicity to onion bulbs at and at 3 days and 2 months, respectively. The bacterium also caused soft rot on potato and showed hypersensitive reactions to tobacco and potato. The causal bacterium of onion soft rot was identified as Pseudomonas marginalis based on morphological, biochemical, and physiological characteristics including LOPAT, Soft rot in onion under low temperature storage caused by P. marginalis has not been previously reported.

Powdery mildew symptoms were frequently on plants of goat`s-beard (Aruncus dioicus var. kamtschaticus) found cultivated in the island Ulleungdo in June 2008. The symptoms appeared as powdery mycelial colonies and dark brown cleistothecia on leaves, petioles, stems and budding flowers of the plant. Incidence of the disease was as high as 50-80% in the goat`s-beard fields. Specimens of the diseased plants were collected and examined for morphological characteristics of the causal fungus. On the basis of morphological characteristics of the conidial stage and the teleomorph, the fungus was identified as Podosphaera ferruginea. This is the first report of goat`s-beard powdery mildew caused by Podosphaera ferruginea in Korea.

Mango ( Mangifera indica L.), an economically important fruit cropin the subtropics and tropics, was recently introduced into Korea. Itis being cultivated over an area of 20 ha with an annual productionof approximately 300 tons in Jeju Island. In July 2010, stem-end rotswere found on fruits of mango (cv. Irwin) grown in a greenhouse inJeju. In the early stage, the affected fruits appeared as small brownspots. As they enlarged, the lesions became circular, dark brown toblack and water-soaked patches and progressed from the surface toinner part of the fruit (Fig. 1A). Two fungal isolates were obtained from lesions on mango fruits.Cultures were initially white to smoke grey, with fluffy aerialmycelium on potato dextrose agar and became gray or black with afew medium grays in laterstage (F ig.1B) . The pycnidia produced onthe 14-day-old cultures (Fig. 1C) were simple, often aggregated,stromatic, ostiolate and hairy. Paraphyses within the pycnidia werehyaline,cy lindrica septate, occasionallyl, branched. Conidiogenouscells were hyaline, thin-walled, smooth, cylindrical, holoblastic(Fig. 1D). Young conidia were hyaline, unicellular and subovoid toellipsoid, with a granular content (Fig. 1E). Mature conidia wereone-septate, dark brown, thick walled, ellipsoidal, with longitudinalstriations (Fig. 1F) and measured 17.5 −26.8 × 12.3 −17.1 μm (mean22.7 × 14.7 μm). No teleomorph was observed in culture. The twofungal isolates were identified as Lasiodiplodia theobromae (Pat.)Griffon & Maubl. [Synonym: Botryodipodl ia theobromae Pat].bas edon their morphological and cultural characteristics, and correspondedto previous description for the species (Alves et al., 2008).To confirm the identification, the complete internal transcribedspacer (ITS) rDNA regions and translation elongation factor 1-alpha (EF1-α) of the two fungal isolates, ML1001 and ML1005were amplified using the primers ITS1/ITS4 and EF1-688F/EF1-1251R asd escribed by Alvese at . (20l 08) and sequencedTh . ere sultingsequences were deposited in GenBank (Accession numbersJN542561 and JN542562 for ITS rDNA, JN542563 and JN542564for EF1-α). Sequences of reference isolates were retrieved fromGenBank. A phylogenetic tree derived from combined sequences ofITS rDNA and EF1-α was constructed by the neighbor-joiningmethod with Kimura’s two-parameter distance model using MEGAversion 5.0. In the phylogenetic tree, the present isolates placed inthe same clade with L. theobromae in GenBank and clearlydistinguished from the closely related Lasiodiplodia species, L.parva and L. pseudotheobromae (Fig. 2).Pathogenicity tests were made on mango fruits. The fruits wereperforated with 3 mm cork borer, followed by drop-inoculated with100 μl of conidial suspensions (5×10

Mulberry (Morus alba L.) is native to China, and has long beenwidely cultivated to feed the silkworms. Recently, it is being used asa material for medical applications and health food in Korea. In July2009, leaf spot disease severely occurred in some local varieties ofmulberry grown in Suwon, Korea. Among different varieties surveyed,a variety, Hasusang, was found to be highly susceptible to the diseasewhere disease incidence reached nearly 90 percent. The disease usuallyoccurred on leaves close to the ground and gradually progressed toupper leaves. The symptoms appeared initially in the form of small,circular, dark-brown spots less than 1 mm and with age these spotsenlarged to large lesions with diffuse chlorotic halo (Fig. 1A and 1B).A total of eight fungal isolates were obtained from lesions on theleaves of mulberry plants. Acervular conidiomata produced onnecrotic lesions in concentric circles were white to pinkish white,subepidermal, separate or confluent, mostly 150 −200 µm wide (Fig.1C). Conidiophores were hyaline, cylindrical, holoblastic andmeasured 7.3 −21.5 × 2.3−4.5 µm (Fig. 1D). Conidia were hyaline,cylindrical, straight or curved, tapered towards the apex, 1 −6 septateand measured 21.0−68.8 × 2.5−5.2 µm (Fig. 1E). Colonies onpotato dextrose agar were slow growing, compact, producing palered diffuse pigment, white on top surface and dark green withpinkish white edge on reverse side (Fig. 1F)A . ll fungal isolates wereidentified as Phloeospora maculans (Sandri) Allesch . [teleomorphMycosphaerella mori (Fuckel) Wolf] based on their morphologicaland cultural characteristics. The morphological characteristics ofpresent isolates were also similar to those described previously(Punithalingam, 1990; Sutton, 1980).To confirm the results of conventional identification, the riboso-mal DNA-internal transcribed spacer (rDNA-ITS) regions fromMP0930, MP0938 and MP0940 were amplified using the primersITS1/ITS4, and sequenced. The sequences obtained were depositedin GenBank with accession numbers of HQ874466, 874467 and874468. An ITS-based phylogenetic tree was constructed by theneighbor-joining method with Kimura’s two-parameter distancemodel using MEGA version 4.0. The phylogenetic tree showed thatpresent isolates could be distinguished from the other Mycospha-erella species and form an independent clade together with P.maculans in GenBank (Fig. 2). Pathogenicity tests were made on mulberry leaves spray-inoculated with conidial suspension (5 × 10