• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.36-36
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• 2014

Apple blotch, caused by Marssonina coronaria, induce early defoliation in apple and leading to critical economic losses in apple orchards in Korea. Since M. coronaria is difficult to culture, we developed isolation and cultural method. We collected M. coronaria isolates from Gyeongbuk Province and then constructed phylogentic tree based on ITS regions. As the results, phylogenetic relationship indicated that all Korean isolates formed a same cluster and closely related to Chinese isolates [1]. Ecological characteristic of M. coronaria have been observed in apple orchards which located in Gyeongbuk Province from 2011 to present. As the results, the typical apple blotch symptoms were observed from July, and then the infected leaves were discolored and formed acervuli on the leaves. After rainfall, severe infection of symptoms such as discoloration and early defoliation were continuously observed until October. Also overwintered conidia were observed in next March on the fallen diseased leaves [2]. In the last 5 years, ascopores of M. coronaria were not observed in apple orchards which were severely infected by M. coronaria in Korea. Thus, it is assumed that overwintered conidia could be a primary inoculum of M. coronaria. Meanwhile, apple blotch has long latent periods compare to other apple disease. During the latent period, early diagnosis of apple blotch is the most important to control the disease by spray fungicide. In this reason, we developed novel diagnostic method to detect M. coronaria during latent period using optical coherence tomography (OCT) and Loop-mediated isothermal amplification (LAMP) method [2, 3]. In this presentation, it will introduce ecological characterization of M. coronaria in Korea and unique detection technique of M. coronaria in apple. It will be helpful to develop new strategies to control apple blotch in Korea.

• The Korean Journal of Mycology
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• v.42 no.3
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• pp.183-190
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• 2014

Apple blotch is a major apple disease and recently it causes critical economic losses in apple orchards in Korea. In this review, we described the history of apple blotch researches, ecology and life cycle of Marssonina coronaria, cultural and molecular characteristics and simple isolation method as well. Furthermore, characteristic of apple blotch like symptoms, its cause still unknown, occurs frequently in cv. "Fuji" was described in detail.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.429-434
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• 2015

Apple blotch-like symptoms (ABLS) were observed on 'Fuji' apple leaves in Cheongsong, Gunwi and Yeongcheon apple orchards located in Gyeongbuk Province during 2010-2014. Characteristics of ABLS were yellowing, brown spots on leaves, and defoliation, similar to apple blotch diseased (ABD) leaves, which are infected with Marssonina coronaria. It is difficult to differentiate by eye between ABLS and ABD, which has led to misdiagnosis and overuse of fungicides. The present study was conducted to investigate the cause of ABLS using stereomicroscopy, culture isolation, cross-sectional analysis of leaves, and PCR. No acervuli were found on the surface of ABLS leaves and no growth was observed on potato dextrose agar (PDA) plates in culture. Furthermore, cross-sectional analysis revealed similar results, and mycelia were absent in ABLS leaves. By contrast, all these characteristics were present in ABD leaves. Furthermore, no fungi or viruses were detected in ABLS leaves by PCR, suggesting that the disease is not caused by these agents. These findings suggest that ABLS might be a physiological disorder in plants that is distinct from ABD.

• Research in Plant Disease
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• v.24 no.4
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• pp.249-256
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• 2018

Disease occurrence in apple cultivars on 13-30 apple orchards from April to October 1992-2010 was investigated at 30 days intervals in Gyeongbuk, Gyeongnam and Jeonbuk provinces of Korea. Apple cultivar 'Fuji' was found most susceptible and is being damaged by cedar apple rust, scab, gray mold, Alternaria blotch and Marssonia blotch as major leaf diseases that were observed. The percentage of occurrence of these leaf diseases varies from every year. This variation is based on different rainfall and temperature conditions, cultivation, root stock and changed system of fungicide spray during the particular year and season.

• Current Research on Agriculture and Life Sciences
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• v.16
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• pp.84-95
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• 1998

Apple Marssonina blotch, caused by Diplocarpon mali, which has been increasing on apple trees and become one of the most serious diseases on apple trees in Korea since the begining of 1990's. In this study, ecology of Marssonina blotch including disease incidence and spore dispersals was surveyed from 1992 to 1995 in Kyungpook, and factors influencing the incidence of the disease were analyzed. Marssonina blotch began to occur on apple leaves in June and was observed commonly in most of apple orchards after August, and increased rapidly in September. The incidence of this disease was high at the year of low temperature and a lot of precipitation. The conidia discharge began to occur in May and continued to October, and the peak period of spore release was in August and usually more than 70% of total spore release of the year released from August to September. The incidence of the disease was high in the northern and mountain are as such as Yeongjoo, Chungsong, Andong, and relatively low in the southern areas such as Kunwi, Yongchon. Jonathan cultivar was the most susceptible to Marssonina blotch, and Jonagold, Sekaiichi was secondly susceptible and the next Fuji was more susceptible than Tsugaru. The incidence of the disease was relatively high in orchards which cultivation management of irrigation, drainage, air circulation, fertilization, and fungicide spraying were poor.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.133-140
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• 2012

In this study we investigate the use of 2D and 3D scanning optical coherence tomography (OCT) technology for use in apple blotch diagnosis. In order to test the possible application of OCT as a detection tool for apple trees affected by Marssonina coronaria, we conducted several experiments and compared the results from both healthy and infected leaves. Using OCT, we found several distinctive features in the subsurface boundary regions of both the diseased and healthy leaves. Our results indicate that leaves from diseased trees, while still appearing healthy, can be affected by M. coronaria. The A-scan analysis method confirmed that the boundaries found under the subsurface layers can be faint. This shows that M. coronaria can exert its influence on entire apple trees (as opposed to only on leaves with lesions) once it infects healthy trees. Our results indicate that OCT can be used as a noninvasive tool for the diagnosis of fungal disease in apple trees. Microscopic imaging results, performed as a histological study for comparison, correlated well with the OCT results.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.531-538
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• 2011

This study was carried out to investigate the influence of defoliation by Marssonina blotch (Diplocarpon mali Harada et Sawamura) on vegetative growth and fruit quality in 'Fuji'/M.9 apple tree. Soluble solid contents decreased when the defoliation percentage by Marssonina blotch was over 10% before the end of September, and fruit weight decreased when percentage of defoliation was over 30%. Fruit red color and starch contents tend to decrease as percentage of defoliation near the fruit increased. Return bloom, fruit weight, and shoot growth the following year tend to decrease as percentage of defoliation increased. Photosynthetic rate of healthy leaves in bourse shoot during the end of September was maintained about $10{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, effects in increasing fruit growth and soluble solid contents after the end of September. Photosynthetic rates for the damaged leaf, damaged area was over 50% on the leaf surface, while 30% of the photosynthetic rates of healthy leaf are without damage applied with Marssonina blotch at the end of September. The results show that the decrease of fruit quality in defoliation treatments may be caused by the decrease of starch contents in fruit, and that was caused by the photosynthetic rates of leaves near fruit was decreased by Marssonina blotch in the wake of August.

• The Plant Pathology Journal
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• v.24 no.4
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• pp.439-446
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• 2008

A fungicidal spray program for effective control of three major apple diseases in Korea (white rot, bitter rot, and Marssonina blotch) was developed. This was based on our previous studies showing that application of ergosterol biosynthesis inhibitors (EBIs) in early or mid-August can eradicate white rot infection in fruit and that some protective fungicides show after-infection activity against white rot. The basic spray program focused on control of white rot, the main target disease, and the fungicides were sprayed at 15-day intervals from petal fall to late August using fungicides that show after-infection and EBI activity. The basic spray program was modified over 4 successive years to improve control efficacy against bitter rot and Marssonina blotch, which sometimes cause as much damage as white rot. Modifications to the regime were made every year by replacing one fungicide in the basic program at a specific spraying time. Substitution of only one fungicide in the spray program, even early in the growing season, greatly influenced the final disease incidence at harvest. Applying this principle, a moderately efficient spray program for cv. Fuji that increased the spray interval from 10 to 15 days and thus reduced the number of sprays required per crop season was developed.

• Research in Plant Disease
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• v.21 no.4
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• pp.261-267
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• 2015

During the period from 2013 to 2014, disease occurrences by various pathogens in apple cultivars have been investigated in northern Gyeongbuk province of Korea. Anthracnose, white rot, Alternaria leaf spot, Marssonina blotch, and bacterial shoot blight as major diseases have been observed. Pathogens isolated from the symptomatic plants were identified as Colletotrichum gloeosporioides for anthracnose, Botryosphaeria dothidea for white rot, Alternaria alternata for Alternaria leaf spot, Marssonina mali for Marssonina blotch, and Pseudomonas syringae pv. syringae for bacterial shoot blight. Of all diseases, the bacterial shoot blight has been severely increased in chronically infested fields in Gyeongbuk province.

• Journal of Biosystems Engineering
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• v.41 no.3
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• pp.255-262
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• 2016

Purpose: Fuji apples are one of the top selling exports for South Korea bringing in over $233.4 million in 2013. However, during the last few decades, about half of the Fuji apple orchards have been infected by Apple Marssonina Blotch disease (AMB), a fungal disease caused by Diplocarpon mali., which takes about 40 days to exhibit obvious visible symptoms. Infected leaves turn yellow and begin growing brown lesions. AMB promotes early defoliation and reduces the quality and quantity of apples an infected tree can produce. Currently, there is no prediction model for AMB on the market. Methods: The Precision Agriculture Laboratory (PAL) at the University of Florida (UF) has been working with the National Academy of Agricultural Science, Rural Development Administration, South Korea to investigate the use of hyperspectral data in creating an early detection method for AMB. The RDA has been researching hyperspectral techniques for disease detection at their Apple Research Station in Gunwi since 2012 and disseminates its findings to the local farmers. These farmers were surveyed to assess the state of knowledge of AMB in the area. Out of a population of about 750 growers, 111 surveys were completed (confidence interval of +/- 8.59%, confidence level of 95%, p-value of 0.05). Results: The survey revealed 32% of the farmers did not know what AMB was, but 45% of farmers have had their orchards infected by AMB. Twenty-five percent could not distinguish AMB from other symptoms. Overwhelmingly, 80% of farmers strongly believed an early detection method for AMB was necessary. Conclusions: The results of the survey will help to evaluate the outreach programs of the RDA so they can more effectively educate farmers on the identifying, treating, and mediating AMB.