• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.282-284
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• 1995

Grey leaf spot on tomato plants was first observed in Sedo-myeon, Puyo-kun, Chungnam province of Korea in 1994. This disease which had not been reported before in Korea exhibited different symptoms from those of other leaf spot diseases on tomato plants. The symptoms were characterized by small irregular-shaped spots on leaves at the initial stage of the infection, subsequent spread and coalescence of the spots throughout the leaves with ultimate necrosis, and abscission from the plants. When healthy tomato plants were inoculated with a conidial suspension of the fungus isolated from the lesion of a diseased plant in a field, the same characteristic symptoms as those in the field were produced. Furthermore, the same pathogen could be reisolated from the lesions formed buy the inoculation. Conidial characteristics of the pathogen were as follows; oblong shape with constricted 3 transverse septa, round-shaped base, round- or point-shaped apex, size of 45~75$\times$12.5~17.5 ${\mu}{\textrm}{m}$, and 3.5 : 1 ratio of length to width. The pathogen was identified as Stemphylium lycopersici and thus this is the first report on the occurrence of grey leaf spot disease on tomato plants caused by s. lycopersici in Korea.

• The Plant Pathology Journal
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• v.23 no.2
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• pp.57-61
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• 2007

Whitefly-transmitted geminiviruses (WTGs) are economically important pathogens causing serious damage on tomato and chilli pepper in Indonesia. Geminiviruses are readily transmitted by its insect vector, sweetpotato whitefly (Bemisia tabaci). However, greenhouse whitefly (Trialeurodes vaporariorum), another species of whitefly, is commonly found together with B. tabaci in the field. Incidence of yellow leaf curl disease in tomato and chilli pepper is probably correlated with the population of whitefly complex. It is becoming important to find the role of T. vaporariorum in the spread of the disease. Therefore, research is conducted to study the characteristic relationship between tomato leaf curl begomovirus (ToLCV) and two species of whitefly. The two species of whitefly, B. tabaci and T. vaporariorum, was capable to transmit ToLCV although it was evidenced that B. tabaci is more effective as insect vector of ToLCV in tomato and chilli pepper. A single B. tabaci was able to transmit ToLCV to tomato with a minimum acquisition and inoculation access period of 10 h. Transmission of ToLCV by T. vaporariorum required at least 10 insects per plant with a minimum acquisition and inoculation access period of 24 h. The transmission efficiency will increase with longer acquisition and inoculation access period of the insect and the higher number of insect per plant.

• The Plant Pathology Journal
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• v.35 no.2
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• pp.137-148
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• 2019

In search of an effective biological control agent against the tomato pathogen Fusarium oxysporum f. sp. lycopersici, rhizospheric soil samples were collected from eight agro-ecological zones of Bangladesh. Among the bacteria isolated from soil, 24 isolates were randomly selected and evaluated for their antagonistic activity against F. oxysporum f. sp. lycopersici. The two promising antagonistic isolates were identified as Brevundimonas olei and Bacillus methylotrophicus based on morphological, biochemical and molecular characteristics. These two isolates were evaluated for their biocontrol activity and growth promotion of two tomato cultivars (cv. Pusa Rubi and Ratan) for two consecutive years. Treatment of Pusa Rubi and Ratan seeds with B. olei prior to inoculation of pathogen caused 44.99% and 41.91% disease inhibition respectively compared to the untreated but pathogen-inoculated control plants. However, treatment of Pusa Rubi and Ratan seeds with B. methylotrophicus caused 24.99% and 39.20% disease inhibition respectively. Furthermore, both the isolates enhanced the growth of tomato plants. The study revealed that these indigenous bacterial isolates can be used as an effective biocontrol agent against Fusarium wilt of tomato.

• Research in Plant Disease
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• v.29 no.1
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• pp.82-87
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• 2023

Exogenous ferrous chloride (FeCl₂) suppressed in vitro growth of Ralstonia pseudosolanacearum, causing bacteria for tomato bacterial wilt. More than 50 μM of FeCl₂ reduced the in vitro bacterial growth in dosedependent manners. Two to 200 μM of FeCl₂ did not affect the fresh weight of detached tomato leaves at 3 and 5 days after the petiole dipping without the bacterial inoculation. The bacterial wilt of the detached tomato leaves was evaluated by inoculating two different inoculum densities of R. pseudosolanacearum (10⁵ and 10⁷ cfu/ml) in the presence of FeCl₂. Bacterial wilt in the detached leaves by 10⁵ cfu/ml was efficiently attenuated by 10-200 μM of FeCl₂ at 3 and 5 days post-inoculation (dpi), but bacterial wilt by 10⁷ cfu/ml was only reduced by 200 μM of FeCl₂ at 3 and 5 dpi. These results suggest that iron nutrients can be included in the integrated disease management of tomato bacterial wilt.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.655-668
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• 2012

Foliar diseases are major constraints to profitable organic tomato production. Especially, powdery mildew, leaf mold and gray mold of tomato occur severely on organic cultured tomatoes in Korea. This study was conducted to develop organic tomato cultivation technology using environmental-friendly disease control methods (resistance cultivar planting, air circulation fan installation, oil-egg yolk mixtures, and microbial agents). When tomatoes were cultivated in plastic film house installed with air circulation fan, daily range of temperature was decreased by $2{\sim}7^{\circ}C$, average relative humidity was decreased by 1~5% compared to those in plastic house without air circulation fan. Consequently, incidence of tomato leaf mold and tomato gray mold was reduced by 55.0% and 24.4%, respectively. Control effect of microbial agents and oil-egg yolk mixtures against major tomato diseases was examined in plastic house. As a result, the control value of microbial agents against tomato gray mold and tomato leaf mold showed at the range of 49.0~55.9 %(gray mold) and 39.2~58.2%(leaf mold), respectively. The control value of oilegg yolk mixtures against tomato powdery mildew showed 97.6%. Fifteen tomato cultivars were evaluated for disease resistance against leaf mold and powdery mildew in organically cultivated tomato field. Among 15 tomato cultivars, seven cultivars including 'Super-top' were found to be high resistant to tomato leaf mold. Also 'Powerking', one of fifteen tomato cultivars, showed to be high resistant to tomato powdery mildew.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1071-1081
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• 2020

Essential oils (EOs) have been shown to be plant-extracted antimicrobial agents. However, there are limited studies investigating the efficacy of EOs against pathogens. Among them, tea tree oil (TTO) is extracted from Melaleuca alternifolia, which is also used as an antifungal agent. In this study, the effect of TTO was investigated on the suppression of melon powdery mildew caused by Podosphaera xanthii and tomato leaf mold disease caused by Passalora fulva. Both powdery mildew and leaf mold diseases were significantly suppressed by a spray of TTO. Eighty percent of powdery mildew and 81% of leaf mold disease of the control value were suppressed by 0.5% TTO liquid, when sprayed 3 times every 7 days on the melon and tomato leaves. Inhibition of mycelial growth was also greatly affected by different concentrations of TTO against four different fungal pathogens. Ninety-eight percent of Pseudocercospora fuligena, 97% of P. fulva, 95% of Botrytis cinerea, and 94% of Phytophthora infestans mycelial growth were inhibited by 0.2% to 1.0% of TTO contained in plate media, respectively. However, phytotoxicity in plants by the TTO treatments was revealed when melon and tomato leaves were sprayed with a 1% and 2% concentration of TTO, respectively. Therefore, our findings show that TTO has high antifungal effects against various plant pathogens that occur during crop cultivation. We also suggest that when applying TTO to plant leaves, it is necessary to establish an accurate treatment concentration for different crops.

• Molecules and Cells
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• v.45 no.7
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• pp.502-511
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• 2022

Bacterial volatile compounds (BVCs) exert beneficial effects on plant protection both directly and indirectly. Although BVCs have been detected in vitro, their detection in situ remains challenging. The purpose of this study was to investigate the possibility of BVCs detection under in situ condition and estimate the potentials of in situ BVC to plants at below detection limit. We developed a method for detecting BVCs released by the soil bacteria Bacillus velezensis strain GB03 and Streptomyces griseus strain S4-7 in situ using solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS). Additionally, we evaluated the BVC detection limit in the rhizosphere and induction of systemic immune response in tomato plants grown in the greenhouse. Two signature BVCs, 2-nonanone and caryolan-1-ol, of GB03 and S4-7 respectively were successfully detected using the soil-vial system. However, these BVCs could not be detected in the rhizosphere pretreated with strains GB03 and S4-7. The detection limit of 2-nonanone in the tomato rhizosphere was 1 µM. Unexpectedly, drench application of 2-nonanone at 10 nM concentration, which is below its detection limit, protected tomato seedlings against Pseudomonas syringae pv. tomato. Our finding highlights that BVCs, including 2-nonanone, released by a soil bacterium are functional even when present at a concentration below the detection limit of SPME-GC-MS.

• Journal of Korean Society for Quality Management
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• v.48 no.4
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• pp.581-596
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• 2020

Purpose: purpose of this study was to propose the web application platform which can be to detect and discriminate various diseases and pest of tomato plant based on the large amount of disease image data observed in the facility or the open field. Methods: The deep learning algorithms uesed at the web applivation platform are consisted as the combining form of Faster R-CNN with the pre-trained convolution neural network (CNN) models such as SSD_mobilenet v1, Inception v2, Resnet50 and Resnet101 models. To evaluate the superiority of the newly proposed web application platform, we collected 850 images of four diseases such as Bacterial cankers, Late blight, Leaf miners, and Powdery mildew that occur the most frequent in tomato plants. Of these, 750 were used to learn the algorithm, and the remaining 100 images were used to evaluate the algorithm. Results: From the experiments, the deep learning algorithm combining Faster R-CNN with SSD_mobilnet v1, Inception v2, Resnet50, and Restnet101 showed detection accuracy of 31.0%, 87.7%, 84.4%, and 90.8% respectively. Finally, we constructed a web application platform that can detect and discriminate various tomato deseases using best deep learning algorithm. If farmers uploaded image captured by their digital cameras such as smart phone camera or DSLR (Digital Single Lens Reflex) camera, then they can receive an information for detection, identification and disease control about captured tomato disease through the proposed web application platform. Conclusion: Incheon Port needs to act actively paying.

• Research in Plant Disease
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• v.15 no.3
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• pp.248-253
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• 2009

Chitosan has an antifungal activity and is widely used for control of various plant disease and plants growth in the field in Korea. Disease control efficacy of two preparations (SH-1, SH-2) of mixtures of high and low (chitooligosaccharide) molecular weight chitosan compounds against tomato leaf mold caused by Fulvia fulva was investigated under plastic greenhouse conditions. Both SH-1 and SH-2 formulations displayed potent disease control activity in two experiments. The protective activity of both preparations was comparable to synthetic thiophanate-M. The persistence activity of the formulations was sustained until 21 days after application. Effective concentration of the chtosan compounds for disease control was 1,200 mg a.i./L. In pot tests, chitosan preparations, at a concentration of 600 mg a.i./L, promoted plants growth. These results indicate that the chitosan preparations have a potential as an eco-friendly natural fungicide for the control of tomato leaf mold and plant growth regulator.

• The Plant Pathology Journal
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• v.19 no.3
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• pp.181-183
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• 2003

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 $\mu\textrm{m}$ in diameter with septate setae up to 102-132$\times$6.5 $\mu\textrm{m}$. Conidia were hyaline, unicellular, and 4.2-4.7$\times$l.5-2.0 $\mu\textrm{m}$ long. Optimum temperature for mycelial growth of the p. lycopersici isolates ranged from $20^{\circ}C$ to $25^{\circ}C$. 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.