• 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.

• Analytical Science and Technology
• /
• v.11 no.3
• /
• pp.206-212
• /
• 1998

The major mycotoxins were detected from peppers, onions and garlics infected postharvest pathogens, Alternaria, Penicillium and Fusarium. Analyses of the major mycotoxins were conducted using HPLC. Detected Alternaria mycotoxins per gram of infected postharvest peppers were alternariol (AOH) with amount ranged from small quantity to $440{\mu}g/g$, altenuene (ALT) with amount ranged from small quantity to $103{\mu}g/g$, tenuagonic acid (TeA) with amount ranged from 249 to $342{\mu}g/g$ and alternariol monomethyl ether (AME) with amount ranged from 206 to $294{\mu}g/g$. Penicillium toxins per gram of infected postharvest onions and garlics were citrinin with amount ranged from 2.8 to $18.4{\mu}g/g$, penicillun-G with amount ranged from no detection to $439.0{\mu}g/g$, penicillic acid with amount ranged from no detection to small quantity and patulin with amount ranged from no detection to small quantity. Fusarium toxins per gram of infected postharvest onions and garlics were fusaric acid with amount ranged from no detection to $553.6{\mu}g/g$. However, deoxyrivalenol and nivalenol were not detected from onins and garlics infected by Fusarium.

• Research in Plant Disease
• /
• v.8 no.2
• /
• pp.107-112
• /
• 2002

This study was carried out to identify the causal pathogens and investigated the characteristics of Penicillium spp. isolated from postharvest decay of pear. One hundred and ninety eight Penicillium spp. were isolated from infected pear fruits. The lesions were formed when the isolated pathogen were inoculated into the wounds and unwounds of pear fruit. Total isolates were classified into 15 groups by the size, color, pigment of colony and shape of conidia. These isolates were identified to be P.expansum, P.solitum, and P.crustosum according to the types of morphological, cultural and physiological characteristics. The pathogenicity was higher in wound inoculation at low temperature than unwound one. This result confirmed that wound promoted the disease appearance. P.expansum was appeared to have the most strong virulence, whereas P.solitum and P.crustosum were classified as weak virulent species by pathogenicity test on pear fruits.

• Mycobiology
• /
• v.46 no.3
• /
• pp.242-253
• /
• 2018

Onion (Allium cepa L.) is one of the major vegetable crops in Korea that are damaged and lost by pathogenic fungal infection during storage due to a lack of proper storage conditions. The aim of this study was to determine an appropriate control measure using thymol to increase the shelf life of onions. To control fungal infections that occur during low-temperature storage, it is necessary to identify the predominant fungal pathogens that appear in low-temperature storage houses. Botrytis aclada was found to be the most predominant fungal pathogen during low-temperature storage. The antifungal activity of the plant essential oil thymol was tested and compared to that of the existing sulfur treatments. B. aclada growth was significantly inhibited up to 16 weeks with spray treatments using a thymol solution. To identify an appropriate method for treating onions in a low-temperature storage house, thymol was delivered by two fumigation treatment methods, either by heating it in the granule form or as a solution at low-temperature storage conditions (in vivo). We confirmed that the disease severity was reduced up to 96% by fumigating thymol solution compared to the untreated control. The efficacy of the fumigation of thymol solution was validated by testing onions in a low-temperature storage house in Muan, Jeollanam-do. Based on these results, the present study suggests that fumigation of the thymol solution as a natural preservative and fungicide can be used as an eco-friendly substitute for existing methods to control postharvest disease in long-term storage crops on a commercial scale.

• 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 Korean Journal of Mycology
• /
• v.40 no.2
• /
• pp.118-123
• /
• 2012

In order to develop environment friendly fungicide for the control of citrus green mold (Penicillium digitatum) using endophytic bacteria, the 21 bacterial isolates were isolated from citrus leaves in seven different orchards in Jeju Province. Among the 21 bacterial isolates, 5 bacterial isolates presented antifungal activity against green mold pathogen P. digitatum. The CB3 isolate, which showed the most strong antagonistic effect, was selected through opposite culture against the pathogen. The rod-shaped, gram-positive bacterium CB3 was identified as Bacillus velezensis based on morphological, physiological characteristics, 16S rDNA, and gyr A gene sequence analysis. The isolate CB3 showed strong antifungal activity against two citrus postharvest pathogen P. digitatum. Citrus fruits were treated by wound inoculation with P. digitatum pathogen, and the control efficacy of CB3 culture broth was 66.7% ($1{\times}10^8$ cfu/ml). In conclusion, The stability of CB3 and its strong antifungal activity also lead us to believe that it has potential for application as an environment friendly biological control agent.

• Mycobiology
• /
• v.49 no.2
• /
• pp.122-132
• /
• 2021

The reexamination of the fungal genus Botryosphaeria on 12 plant species of 10 families was carried out based on molecular phylogenetic analyses using the regions of translation elongation factor 1-α, β-tubulin, DNA-directed RNA polymerase II subunit, and internal transcribed spacer region of rDNA and morphological characteristics. Japanese isolates were divided into five clades and include Botryosphaeria dothidea, B. qingyuanensis, B. sinensis, and Botryosphaeria spp. Two species, B. qingyuanensis and B. sinensis have been newly added to the Japanese mycoflora, but their host plants are not specified. Botryosphaeria tenuispora isolated from Leucothoe fontanesiana and insect galls on fruits of Aucuba japonica has been proposed as a new species.

• 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.

• Korean Journal of Food Science and Technology
• /
• v.50 no.1
• /
• pp.98-104
• /
• 2018

Oxyresveratrol (trans-2, 3', 4, 5'-tetrahydroxystilbene), found in many plants including grape, peanut and mulberry, is a phytoalexin, an antimicrobial and antioxidative substance that rapidly accumulates in areas infected by the pathogen. We examined the accumulation of oxyresveratrol in nine Morus alba L. cultivars with respect to storage time and temperature postharvest and infection with GRAS microorganisms. Among the nine cultivars, the Suwon cultivar showed the highest oxyresveratrol content (9.6-fold increase) postharvest, when stored at $30^{\circ}C$ for 7 days. The optimal temperature and postharvest storage time for oxyresveratrol accumulation was $30^{\circ}C$ and 6 days. When Ramulus mori was infected with five microorganisms, the accumulation of oxyresveratrol increased over 4-fold in response to B. coagulans infection. These results suggest that oxyresveratrol accumulation is influenced by storage temperature, storage time, Ramulus mori cultivars, and microbial attack. Therefore, postharvest storage for an appropriate time period at a suitable temperature might be a useful way to industrially produce Ramulus mori cultivars with high oxyresveratrol content.

• The Korean Journal of Mycology
• /
• v.25 no.1 s.80
• /
• pp.30-34
• /
• 1997

Glomerella cingulata (conidial state: Colletotrichum gloeosporioides) was identified as the causal organism of anthracnose of citrus on the basis of morphological characteristics of the conidial state of the fungus isolated from infected leaves of Satsuma mandarin and its ascigerous state isolated from diseased twigs. The pathogen infected the leaves of Satsuma mandarin, citron and Natsu daidai only by wound inoculation. The optimum temperature range for mycelial growth and sporulation of conidia of the strain was $25{\sim}30^{\circ}C$, respectively. The characteristics of anthracnose strain of Satsuma mandarin such as growth rate and color of colony, shape and size of conidia, and appressoria were similar to those of FGG strain. However, the strain isolated from infected leaves and twigs of Satsuma mandarin was different from FGG strain to cause postharvest anthracnose of citrus, because some of morphological and pathological characteristics of the strain isolated did not correspond to those of FGG strain.