• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.35-40
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• 2016

Recently, bacterial angular leaf spot disease, caused by Xanthomonas fragariae, causes severe damage in strawberry production and its' export to other countries, since the pathogen has been classified as an A2 quarantine pathogen. Typical the Angular Leaf Spot (ALS) disease represent that water-soaked angular spots symptoms, bacteria ooze exudate under relatively high humidity condition and later the spot become reddish brown on the leaf surface. The pathogen disseminated by irrigation water, infected mother plant and farmer's hand. In this study, we reported that rubbing inoculation method showed more effective in the pathogen dissemination than infiltration with needles, regardless the strawberry cultivars. Additionally, Dichloroisocyanurate (NaDCC) treatment in commercial strawberry fields provided reliable efficiency to reduce the bacterial angular leaf spot disease incidency and severity.

• The Plant Pathology Journal
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• v.32 no.4
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• pp.290-299
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• 2016

Strawberry bacterial angular leaf spot (ALS) disease, caused by Xanthomonas fragariae has become increasingly problematic in the strawberry agro-industry. ALS causes small angular water-soaked lesions to develop on the abaxial leaf surface. Studies reported optimum temperature conditions for X. fragariae are $20^{\circ}C$ and the pathogen suffers mortality above $32^{\circ}C$. However, at the nursery stage, disease symptoms have been observed under high temperature conditions. In the present study, results showed X. fragariae transmission was via infected maternal plants, precipitation, and sprinkler irrigation systems. Systemic infections were detected using X. fragariae specific primers 245A/B and 295A/B, where 300-bp and 615-bp were respectively amplified. During the nursery stage (from May to August), the pathogen was PCR detected only in maternal plants, but not in soil or irrigation water through the nursery stage. During the cultivation period, from September to March, the pathogen was detected in maternal plants, progeny, and soil, but not in water. Additionally, un-infected plants, when planted with infected plants were positive for X. fragariae via PCR at the late cultivation stage. Chemical control for X. fragariae with oxolinic acid showed 87% control effects against the disease during the nursery period, in contrast to validamycin-A, which exhibited increased efficacy against the disease during the cultivation stage (control effect 95%). To our knowledge, this is the first epidemiological study of X. fragariae in Korean strawberry fields.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.287-294
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• 2015

In Korea, Strawberry bacterial angular leaf spot disease was first reported in 2010. The disease of strawberry caused serious problem for strawberry producers and export. To field test, we applied the bactericides in June and October as nursery stage and cultivation stage, respectively. In nursery stage with high temperature condition, Oxolinic acid (97.2%) showed significant control effect. In cultivation stage with low temperature condition is soil sterilization and soil non- sterilization the control effect. In cultivation stage in soil sterilization stage Validamycin (93.3%) showed reliable control effect against the disease. Also, soil non-sterilization stage with low control effect of Validamycin (80%) showed control effect the lower than a soil sterilization stage.

• Research in Plant Disease
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• v.8 no.2
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• pp.78-83
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• 2002

Tobacco diseases have not been recorded until 1900s in Korea, where tobacco plants were introduced at early 1700s. Practical researches on the disease have been conducted since mid 1960s. Major ten tobacco diseases were mosaic caused by tobacco mosaic virus·potato virus Y·cucumber mosaic virus, bacterial wilt, hollow stalk, wild fire caused by angular leaf spot strain, black shank, brown spot, powdery mildew and fusarium wilt. But their annual occurrences were varied according to changes of tobacco varieties and their cultivating practices. As no useful chemicals, several biological tactics have been developed to control the viral or bacterial diseases that give significant economic damages on sustainable crop yield, but not practicable to field farming condition yet. Transgenic tobacco plants containing foreign disease resistant genes have been developed by current bio-technology, but not released to farmers yet. Though some disease-resistant tobacco varieties have been developed by the conventional breeding technology and currently used by farmers, their disease controlling efficacy have been diminished by occurrence of the new strain or race. Future research on tobacco diseases has been focused on technical development to produce high quality tobacco with less production cost, which leads Korean tobacco industry to keep its competence against foreign industry and decreasing overall market.

• Research in Plant Disease
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• v.22 no.1
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• pp.9-17
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• 2016

Nationwide survey for angular leaf spot (ALS) of strawberry caused by Xanthomonas fragariae, a quarantine disease in Korea, was performed in November 2012. In the survey, ALS was observed in eighty eight farmers' fields of Sukok, Jinju and Okjong, Hadong in Gyeongnam Province, and one field in Namwon of Jeollabuk Province. The infected field of Namwon closed immediately after the disease diagnosed ALS. In detailed survey of Sukok and Okjong areas during February 2012 to January 2015, ALS occurrence decreased from 45% farmer's fields on December 2012 to 5% on January 2015, and from 38% on November 2013 to 5% on January 2015, respectively. Phenotypic characteristics of the Korean strains were similar to those of the type strain of X. fragariae. A multilocus sequence analysis of Korean strains of X. fragariae was conducted using four genes; dnaK, fyuA, gyrB, and rpoD. All the Korean strains had the same sequences of the four genes. The concatenated sequences of the Korean strains shared 100% with that of the type strain of X. fragariae. All strawberry cultivars tested were susceptible to the strains of X. fragariae two weeks after inoculation. The inoculated sites were necrosis and expanded, which were rated 4 based on evaluation of inoculation site.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.47-53
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• 2015

Various diseases occur in fruits, leave and roots during strawberry cultivation and cause severe economical damage and huge amount of chemical fungicide use. Recently, as consumers' interest in safety of foods and organic agriculture produces have increased, control measures using alternatives for chemical fungicides have been newly developed in various ways. This study was conducted to test antifungal activity and control effect of sodium dichloroisocyanurate (NaDCC), using as disinfectants, against major disease pathogens of strawberry, Fusarium oxysporum (Fusarium wilt), Colletotrichum gloeosporioides (Anthracnose) and Phytophthora sp. (Phytophthora blight), and Xanthomonas fragariae (bacterial angular leaf spot) and evaluate availability as environment-friendly materials. When NaDCC was treated at the concentration range of 150 to 300 ppm, it suppressed significantly hyphal growth and reduced spore germination by more than 28%. In field condition, NaDCC showed excellent control effect (control value: 50%) against the bacterial angular leaf spot disease. Based on above-described results, we suggested that NaDCC can be used as alternative candidates to chemical pesticide alternatives of for controlling strawberry diseases.