• The Plant Pathology Journal
• /
• v.33 no.4
• /
• pp.434-439
• /
• 2017

Incidence rates of diseases in kiwiberry orchards were investigated monthly from late June to late September in Gwangyang and Boseong in 2015 and 2016. The impact of postharvest fruit rot was investigated during ripening after harvest. Bacterial canker was only observed on one single tree in 2015, but black rot, powdery mildew, leaf spot and blight, and postharvest fruit rot diseases were problematic throughout the study period in both 2015 and 2016. Incidence rates of the diseases varied with kiwiberry cultivar, region and sampling time. Incidence rates of powdery mildew, leaf spot and blight diseases increased significantly during the late growing stages near fruit harvest, while black rot peaked in late August. Incidence rate of postharvest fruit rot on fruit without fruit stalks was less than half of fruit with fruit stalks, regardless of kiwiberry cultivars. Among the four cultivars, Mansu was relatively resistant to black rot and postharvest fruit rot diseases. In our knowledge, this is the first report of various potential pathogens of kiwiberry in Korea.

• Research in Plant Disease
• /
• v.10 no.4
• /
• pp.260-267
• /
• 2004

Fusarium spp. were isolated from the postharvest fruit rot of oriental melon fruits at commercial fruit markets in Korea during 2001 to 2003. The decayed fruits were covered with the fungal mycelia and eventually soft rotted. The disease started at the fruit stalk area, the calyx end of the fruit and skin of fruit. As the disease advanced, white to pinkish mycelia covered with the surface of decayed fruit. The cultural and morphological characteristic of Fusarium spp. were compared with descriptions of those reported previously, and identified as Fusarium equiseti, F. graminearum, F. moniliforme, F. proliferatum, F. sambucinum, and F. semitectum. Pathogenicity of the isolates was proved by artificial wound and unwound inoculation onto the healthy fruits. Two days after inoculation, aerial mycelia were noticed on the wound inocultion region of the fruit and developed soft rot symptoms. Although Fusarium spp. causing fruit rot disease in oriental melon have been reported in Korea, identification of the those species was not described. Therefore, this is the first report of Fusarium spp. causing postharvest fruit rot on oriental melon in Korea.

• Mycobiology
• /
• v.40 no.3
• /
• pp.214-216
• /
• 2012

Soft rot on banana fruit caused by Rhizopus oryzae was identified for the first time in Korea. Colonies were white to light brown and formed numerous sporangiospores. Optimum temperature for mycelial growth was $30^{\circ}C$. Sporangia were globose and $30{\sim}200{\mu}m$. Sporangiophores were usually straight, $8{\sim}20{\mu}m$, and rhizoids usually in groups of 3~5. Columella were globose to sub-globose and $90{\sim}110{\mu}m$. Sporangiospores were sub-globose or oval and $4{\sim}10{\mu}m$. Based on its mycological characteristics, molecular analysis, and pathogenicity to host plants, this fungus was identified as Rhizopus oryzae Went & Prisen Geerligs. This is the first report of soft rot on banana caused by Rhizopus oryzae in Korea.

• Research in Plant Disease
• /
• v.9 no.4
• /
• pp.196-200
• /
• 2003

Sixteen hundred fruits were randomly collected from 16 kiwifruit (Actinidia deliciosa) orchards in Jeonnam, Gyeongnam and Jejn provinces in Korea in 2000 and incidences of postharvest fruit rots were examined. The overall disease incidence was 32% and varied much with locations of orchards ranging from 5 to 68%. The percentages of kiwifruits showing internal, external, and both internal and external symptoms were 21.9%, 4.9%, and 5.2%, respectively. Several fungi were isolated from rotten fruits; Botryosphaeria dothidea, Diaporthe actinidiae and Botrytis cinerea were the major pathogens with the average isolation rates of 83.3%, 11.9% and 1.4%, respectively. Based on the symptoms on kiwifruits and the characteristics, the postharvest fruit rots caused by B. dothidea and D. actinidiae are suggested to be named as ripe rots and stem-end rots, respectively.

• Research in Plant Disease
• /
• v.24 no.3
• /
• pp.175-181
• /
• 2018

Incidence rates of bacterial canker, bacterial leaf spot and postharvest fruit rot on the Korean yellow-fleshed kiwifruit cv. Haegeum were compared with those on the most popular green-fleshed kiwifruit cv. Hayward grown in several naturally infected kiwifruit orchards in 2013 and 2014. The percentages of diseased leaves caused by bacterial canker were 18.5% and 17.3% on Hayward in 2013 and 2014, but those on Haegeum were 1.2% and 0%, respectively. The percentages of diseased leaves caused by bacterial leaf spot on Hayward were 63.5% and 16.2% in 2013 and 2014, respectively, but no bacterial leaf spots were observed on Haegeum in both years. The average percentages of diseased fruits caused by postharvest fruit rot were 24.2% and 20.5% on Hayward in 2013 and 2014, while 6.3% and 4.4% and Haegeum, respectively. Botryosphaeria dothidea was turned out to be the major pathogen of postharvest fruit rot on both cultivars.

• The Plant Pathology Journal
• /
• v.37 no.4
• /
• pp.347-355
• /
• 2021

Ripe rot caused by Botryosphaeria dothidea is one of the serious diseases of postharvest kiwifruit. In order to control ripe rot on Actinidia chinensis cultivar 'Zesy002', several commercial agrofungicides were selected by an antifungal test on an artificial medium. Furthermore, disease suppression by the selected fungicides was evaluated on the kiwifruit by inoculation with a conidial suspension of B. dothidea. On the artificial media containing boscalid + fludioxonil was shown to be the most effective antifungal activity. However, in the bio-test pyraclostrobin + boscalid and iminoctadinetris were the most effective agrochemicals on the fruit. On the other hand, the infection structures of B. dothidea on kiwifruit treated with pyraclostrobin + boscalid were observed with a fluorescent microscope. Most of the fungal conidia had not germinated on the kiwifruit treated with the agrochemicals whereas on the untreated fruit the fungal conidia had mostly germinated. Electron microscopy of the fine structures showed morphological changes to the conidia and branch of hyphae on the kiwifruit pre-treated with pyraclostrobin + boscalid, indicating its suppression effect on fungal growth. Based on this observation, it is suggested that ripe rot by B. dothidea may be suppressed through the inhibition of conidial germination on the kiwifruit treated with the agrochemicals.

• The Plant Pathology Journal
• /
• v.36 no.6
• /
• pp.570-578
• /
• 2020

Rhizopus rot is a serious postharvest disease of various crops caused by Rhizopus spp. and controlled mainly by synthetic fungicides. We detected the antifungal activity of a culture extract of Setosphaeria rostrata F3736 against Rhizopus oryzae. The active ingredient was identified as moriniafungin, a known sordarin derivative, which showed minimum inhibitory concentrations of 1-8 ㎍/ml against Colletotrichum spp. and 0.03-0.13 ㎍/ml against Rhizopus spp. in vitro. Moriniafungin showed protective control efficacies against Rhizopus rot on apple and peach fruits. Treatment with 25 ㎍/ml moriniafungin delimited the lesion diameter significantly by 100% on R. oryzae-inoculated apple fruits compared with the non-treated control. Treatment with 0.04 ㎍/ml of moriniafungin reduced the lesion diameter significantly by 56.45%, and treatment with higher concentrations of 0.2-25 ㎍/ml reduced the lesion diameter by 70-90% on Rhizopus stolonifer var. stolonifer-inoculated peach fruit. These results suggest moriniafungin has potential as a control agent of postharvest diseases caused by Rhizopus spp.

• The Plant Pathology Journal
• /
• v.29 no.2
• /
• pp.168-173
• /
• 2013

Apple ring rot disease, caused by Botryosphaeria dothidea (Moug. ex. Fr) Ces. et de Not., is one of the most important diseases on apple fruits. In this study, strain 9001 isolated from healthy apple fruits from an infested orchard was evaluated for its biocontrol activity against apple ring rot in vitro and in vivo. Strain 9001 showed obvious antagonistic activity to B. dothidea YL-1 when plated on potato dextrose agar. Soaking healthy apples in the bacterial suspensions of strain 9001 prior to artificial inoculation of fungal pathogen resulted in a dramatic decrease in disease incidence when compared to the control. Moreover, either field application in the growth season or postharvest treatment of apples from infected orchards with bacterial suspensions of strain 9001 resulted in significantly reduced disease incidence within the storage period for 4 months at room temperature. Based on the phylogenetic analysis of 16S rRNA and the gyrA gene, strain 9001 was identified as Bacillus amyloliquefaciens. These results indicated that B. amyloliquefaciens 9001 could be a promising agent in biocontrol of apple ring rot on fruit, which might help to minimize the yield loss of apple fruit during the long postharvest period.

• Research in Plant Disease
• /
• v.9 no.4
• /
• pp.205-208
• /
• 2003

Fungicides of tebuconazole wp, iprodione wp and flusilazole wp were applied for the control of postharvest fruit rots of kiwifruit (Actinidia deliciosa) in the field in 2000 and 2001. More than 3 consecutive applications of these fungicides from the late June with 10-day-interval successfully controlled the diseases. It was found in the field trial in 2002 that 4 consecutive spays from mid of June with 10-day-interval was found to be the most effective application program for tebuconazole wp, iprodione wp and flusilazole wp, The results suggested that currently registered fungicides of benomyl wp and thiophanate-methyl wp can be substituted by tebuconazole wp, iprodione wp and flusilazole wp for the control of the diseases in Korea. Use of these fungicides can restrain emergence of fungicide resistant strains of postharvest fruit rot pathogens with benefit of reduced application of chemicals for food safety and environmental conservation.

• Research in Plant Disease
• /
• v.9 no.3
• /
• pp.170-173
• /
• 2003

For the effective chemical control to minimize infection of storage pathogens on kiwifruit in the field, this study was conducted to screen alternative fungicides which could be substituted for the fungicides Benomyl WP and Thiophanate-methyl 제 registered for the control of postharvest fruit rats of kiwifruit in Korea. Among the 8 fungicides tested, Tebuconazole WP, Iprodione WP and Flusilazole WP showed higher inhibitory effects on themycelial growths of 3 major pathogens of postharvest fruit rots, Botryosphaeria dothidea, Diaporthe actinidiae and Botrytis cinerea on potato dextrose agar. They also showed control efficiencies as high as those of Benomyl WP and Thiophanate-methyl WP on postharvest fruit rots in the field. They might be good candidates for fungicieds for the control of postharvest fruit rots of kiwifruit.