• Mycobiology
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• v.39 no.3
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• pp.200-205
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• 2011

Marssonina coronaria associated with apple blotch disease causes severe premature defoliation, and is widely distributed in Korea. Thirteen isolates were collected from orchards located in Gyeongbuk Province from 2005~2007. All isolates displayed over 99.6% and 99.2% sequence similarity to each other in internal transcribed spacer regions and partial sequences of 28S rDNA, respectively. The isolates were phylogenetically closely related to Chinese isolates. Selected isolates did not differ in their pathogenicity. The optimum conditions for fungal growth were $20^{\circ}C$ and pH 6 on peptone potato dextrose agar (PPDA). Peptone and mannose were the best nitrogen and carbon source, respectively. Fungal growth was better on PPDA than on common potato dextrose agar. This study provides valuable information for integrated disease management program and facilitates the routine culturing of M. coronaria.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.271-276
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• 2015

Crab apple cultivars, 'Maypole', 'Tuscan', and 'Manchurian', were evaluated as potential pollinizers of major apple cultivars, 'Fuji', 'Hongro', and 'Tsugaru', cultivated in high-density apple orchard systems. Numerous cultivar characteristics, including blooming time, pollen germination, fruit set, disease and pest resistance, and self-incompatibility, were examined. The blooming times of both 'Maypole' and 'Tuscan' ranged from April 19 to May 5, which was 2-4 days earlier than those of the major commercial apple cultivars. PCR analysis did not reveal the presence of any of the S-alleles (S1, S3, S7, or S9) identified in major commercial apple cultivars. In addition, the percentage of the fruit set was high after trees were artificially fertilized with crab apple pollen. Artificially cross-pollinated fruits were of similar or higher quality than open-pollinated fruits. They also demonstrated resistance to apple blotch, sooty blotch, and fly speck. The results indicate that the two crab apples, 'Maypole' and 'Tuscan' would be potential candidates for pollinizers of major apple cultivars in Korea. Use of the pollen of these crap apples in commercial production will improve fruit quality and promote sustainable and robust fruit production.

• The Plant Pathology Journal
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• v.35 no.6
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• pp.585-597
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• 2019

A disease forecast model for Marssonina blotch of apple was developed based on field observations on airborne spore catches, weather conditions, and disease incidence in 2013 and 2015. The model consisted of the airborne spore model (ASM) and the daily infection rate model (IRM). It was found that more than 80% of airborne spore catches for the experiment period was made during the spore liberation period (SLP), which is the period of days of a rain event plus the following 2 days. Of 13 rain-related weather variables, number of rainy days with rainfall ≥ 0.5 mm per day (L_day), maximum hourly rainfall (P_max) and average daily maximum wind speed (W_avg) during a rain event were most appropriate in describing variations in airborne spore catches during SLP (S_i) in 2013. The ASM, Ŝ_i = 30.280+5.860×L_day×P_max-2.123×L_day×P_max×W_avg was statistically significant and capable of predicting the amount of airborne spore catches during SLP in 2015. Assuming that airborne conidia liberated during SLP cause leaf infections resulting in symptom appearance after 21 days of incubation period, there was highly significant correlation between the estimated amount of airborne spore catches (Ŝ_i) and the daily infection rate (R_i). The IRM, ${\hat{R}}_i$ = 0.039+0.041×Ŝ_i, was statistically significant but was not able to predict the daily infection rate in 2015. No weather variables showed statistical significance in explaining variations of the daily infection rate in 2013.

• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.17-29
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• 1995

This study was conducted from 1991 to 1993 to develop a fungicidal spray program for the apples exportable to the United States of America, in which quarantine and pesticide residue in agricultural products are strictly regulated. In 1991, 2 spray schedules were applied to an orchard, in one of which the 7 fungicides registered for apple both in Korea and U.S. were used, and in the other of which the Bordeaux mixture for which the tolerance was exempted in U.S. was used 2 times along with those 7 fungicides. The apple white rot and fruit infection by Alternaria mali were not effectively controlled by the 7 fungicides alone; however, the control efficacy was raised by adding the Bordeaux mixture to the spray schedule. In 1992, 4 spray schedules were applied in which the kinds of fungicides and spray intervals were different one another. The results suggested that an effective spray program can be developed by adopting the Bordeaux mixture for 3 times or adopting the imminoctadine-triacetate which has not tolerance level in U.S. for same times in the vulnerable stage of apple white rot and alternaria blotch. In spite of the high efficacies against major apple diseases, the Bordeaux mixture could not be recommended to the apple growers due to the various defects such as restrictions in compatibility with insecticides and acaricides, troublesomeness in preparation and spray, especially the harmful effect on the finish of Fuji apples. In 1993, a spray program adopting 3 times of imminoctadine-triacetate during the growing season of apple was developed, which not only can effectively control the major apple diseases but also avoid the pesticide residue problems if it was sprayed 2 or 3 times after bagging. On the basis of the 3 years results, a basic fungicide spray program was formulated in which 1~3 times of imminoctadine-triacetate and 1~2 times of bitertanol were adopted in addition of the 7 common fungicides registered in both countries. In the results of application of the spray schedule to the actual farming in the 4 areas of Kyungpook Province in 1994, no noticeable defects were detected at the first year trial. However, this spray program will be continuously evaluated and modified to obtain better control efficacies against major apple diseases.

• The Plant Pathology Journal
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• v.25 no.3
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• pp.270-279
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• 2009

During the course of a study to develop a spraying program at 15-day spray intervals, two important findings were identified allowing for further reduction of spray frequency by increasing the spray interval. In evaluating the contribution of fungicides from a 15-day spray interval program, control of white rot, which is of prime importance in Korea, was not affected, in spite of the extended spray interval caused by omitting the fungicides during the season. In another experiment assessing the duration of the protective activities of several key fungicides used in the 15-day spray interval program, infection control was maintained for almost 30 days for some fungicide. Based on these two findings, a basic spraying program with a 25-day spray interval was developed. This program was modified for four successive years to improve the control efficacy against bitter rot and Marssonina blotch, which sometimes causes as much damage as white rot.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.375-380
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• 2006

In the survey from 1992 to 2000, twenty-eight parasitic diseases were observed in major apple producing areas in Korea. The predominant apple diseases were white rot(Botryosphaeria dothidea), Marssonina blotch(Marssonina mali), Valsa canker(Valsa ceratosperma), Alternaria leaf spot(Alternaria mali), and bitter rot(Collectotrichum gloeosporioides and C. acutatum). Apple scab that reappeared in 1990 after disappearance for 15 years was disappeared again since 1997. A viroid disease(caused by apple scar skin viroid) was newly found in this survey. The five diseases, fire blight(Erwinia amylovora), black rot(Botryosphaeria obtusa), scab(Cladosporium carpophilum), Monochaetia twig blight(Monochaetia sp.), and brown leaf spot(Hendersonia mali), which had once described in 1928 but no further reports on their occurrence, were not found in this survey. However, blossom blight(Monilinia mali), brown rot(Monilinia fructigena), and pink rot(Trichothecium roseum), which did not occur on apple after mid 1970s, were found in this survey.

• Horticultural Science & Technology
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• v.19 no.3
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• pp.362-366
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• 2001

This survey was carried out to investigate the effect of flooding by heavy rain on growth characteristics and disease incidence of 'Fuji'/M.26 mature apple tree in 1998 at Kyongbuk province. The surveyed regions were Andong, Uisung, and Gunwi area. The six orchards were selected from one area, totally 18 orchards were surveyed. The flooded depth of surveyed orchards was from 70 to 350 cm, and the flooded duration was from 6 to 72 h. Defoliation ratio, number of abnormal budding, and flowering per tree were increased along with the increment of flooded depth and duration. Rooting ratio was decreased rapidly with the increment of flooded duration, and dead root ratio was 16.2% in flooded orchards. Marssonia blotch (Diplocarpon mali), white rot (Botryosphaeria dothidea) of fruit, and phytophthora fruit rot (Phytophthora cactorum) incidence were increased in flooded orchards. The analysis results of pearson correlation coefficient among surveyed items showed that higher relationship of abnormal growth characteristics and increment of disease incidence of 'Fuji'/M.26 apple trees with flooded duration than with flooded depth. With these results, the flooded depth was found to be the main factor for the abnormal growth characteristics and disease incidences of 'Fuji'/M.26 apple trees.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.368.4-369
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• 2001

• Korean Journal Plant Pathology
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• v.10 no.4
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• pp.284-291
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• 1994

In order to establish an appropriate spray schedule to reduce the infection, 11 kinds of chemicals were tested for their properties on the inhibition of spore germination at the surface of apple fruits and the duration of the inhibitory effect after spray of each chemical was examined from late June to early September with basically 10 day intervals. Actual control efficacy of each chemical by the 8 successive spray and the patterns of waterborne spore dispersals during that periods were also examined. Combining those results with the meteorological observation data, actual control efficacy of each chemical in the given periods could be estimated. It was revealed that folpet, Brodeaux mixture, mancozeb, oxine copper and imminoctadine-triacetate could be used at any time during the possible infection periods. Captan and dithianon could also be used except the rainy season due to the short duration of inhibitory efficacy against spore germination under heavy rain. However, the usefulness of propineb, benomyl and chlorothalonil against the apple white rot could not be demonstrated in this experiment. Thiram, even though has not been used for apple white rot, can also be used before or after the rainy season to control not only white rot but also alternaria blotch.

• Korean Journal of Organic Agriculture
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• v.18 no.2
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• pp.221-232
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• 2010

During 2005~2009, current status on the occurrence and the management of the major disease, insect and mite pests were investigated in the non-chemical or organic cultured apple orchards in Korea. Numbers of certified organic or non-chemical apple orchards increased from 14 in 2005 to 78 in 2008. Severe damages on leaves and fruits were caused by the several diseases such as marssonina blotch, bitter rot, white rot, sooty blotch and flyspeck, and the several insect pests such as apple leaf-curling aphid, woolly apple aphid, oriental fruit moth and peach fruit moth on the almost certified organic or non-chemical pest control orchards. About 10 and 18 environmental-friendly materials were used to control diseases and insect or mite pests, respectively. But, lime sulfur and bordeaux mixture to diseases and machine oil, plant oil mixed with egg yolk, and pheromone mating disruptions to insect pests were effective under the adequate conditions.