• The Plant Pathology Journal
• /
• v.15 no.1
• /
• pp.76-78
• /
• 1999

A Phloeospora leaf spot disease on Spiraea prunifolia var. simpliciflora was noticed to commonly occur in Korea. The causal organism of the disease was identified as Phloeospora spiraeicola based on the morphological characteristics of conidiomata and conidia. Pathogenicity of the fungus was proved by artificial inoculation. This is the first record of Phloeospora leaf spot in Korea.

• The Korean Journal of Pesticide Science
• /
• v.6 no.2
• /
• pp.87-95
• /
• 2002

Disease control activities of the methanol extracts from 27 plant species were investigated against six plant diseases such as rice blast, rice sheath blight, tomato gray mold, tomato late blight, wheat leaf rust and barley powdery mildew. The extracts of Humulus japonicus, Hosta longipes, Liriope platyphylla, and Astragalus membranaceus exhibited a great in vivo control activity against rice blast. Similarly, the extracts of Commelina communis and A. membranaceus were highly active on tomato gray mold and barley powdery mildew, respectively. The extracts of H. longipes, L. platyphylla, Solanum nigrum and A. membranaceus showed especially high disease control activity against wheat leaf rust, and then were selected for further tests such as protective, curative, systemic, and lasting activity against wheat leaf rust. The extracts of L. platyphylla and S. nigrum were strong protectant, and that of A. membranaceus possessed both a preventive activity and a curative activity. Systemic disease control by the selected four plant extracts was investigated by examing translaminar activity from leaf-under-surface to leaf-upper-surface and systemic activity by leaf-to-Ieaf movement. All extracts strongly controlled wheat leaf rust by translaminar movement, but hardly controlled the disease by leaf-to-leaf movement. Good lasting activity was also observed against wheat leaf rust from all of the tested extracts. Especially, disease control experiments on wheat seedlings sprayed with the extracts of S. nigrum or H. longipes 7 days prior to inoculation represented control value over 95%. These results suggest that methanol extracts of H. longipes, L. platyphylla, S. nigrum, and A. membranaceus, especially S. nigrum, would potently control wheat leaf rust caused by Puccinia recondita in the fields.

• The Plant Pathology Journal
• /
• v.28 no.2
• /
• pp.212-215
• /
• 2012

Pyrenophora graminea, the causal agent of leaf stripe disease, is an economically important pathogen of barley found worldwide. It is critical to clearly define and standardize the leaf stripe assessment methods to avoid subjectivity and variability between assessors. Therefore, in this study, a comparison between the proportion of diseased plants (DP) and the proportion of diseased leaves (DL) per plant was investigated. Disease assessments were made visually at multiple sample sites in artificially and naturally inoculated research and production fields during four growing seasons. There were significant differences (P = 0.001) among cultivars in mean DP and DL averages, which are consistently higher in susceptible barley. However, DP values increased linearly as DL increased. The slopes and intercepts of the DP-DL relationship were consistent over the four growing seasons. This result might make a significant contribution for leaf stripe assessment in barley breeding programme.

• Horticultural Science & Technology
• /
• v.30 no.2
• /
• pp.137-143
• /
• 2012

Chinese cabbage plant was grown hydroponically for 4 weeks in order to examine the temporal relationship of calcium concentration of the nutrient solution with calcium content in the leaf tissue and susceptibility of the tissue to soft rot disease by $Pectobacterium$ $carotovorum$ ssp. $carotovorum$ (Pcc). Calcium concentration from 0.5 to 32.0 mM was maintained for 1 week using Hoagland & Arnon solution. The calcium content of the leaf was proportionally increased to the concentration of the nutrient in the solution (r = 0.912). In contrast, the severity of soft rot symptom in the young leaves was inversely related with the amount of calcium supplied to the nutrient solution (r = 0.899). Water-soluble chitosan, prepared by hollow fiber filtration (> 100 kDa) was applied into the nutrient solution from 0.0 to 5,000 ppm. The chitosan of 10 ppm was the most effective to promote calcium uptake of the leaf, showing 155% of the control. The same chitosan solution prohibited most soft rot development of the leaf by Pcc, exhibiting only 53% of the control. Among different molecular weight fractions, chitosan fraction obtained from 30-100 kDa molecular weight cut-off promoted calcium uptake the most up to 163% of the control, and reduced the development of soft rot disease recording merely 36% of the control of the leaf tissue. The results obtained in the present study suggest that large scale production of water-soluble chitosan with an optimum molecular weight and its commercial application to Chinese cabbage production will be important to improve yield and quality of the crop.

• The Plant Pathology Journal
• /
• v.25 no.4
• /
• pp.328-332
• /
• 2009

Diseases caused by Pepper yellow leaf curl virus infection is considered to be emerging plant diseases in Indonesia in the last five years. One key factor for disease management is the availability of accurate detection of the virus in plants. Polyclonal antibody for Pepper yellow leaf curl Indonesia virus-Bogor (PYLCIV-Bgr) was produced for detection of the virus using I-ELISA and DIBA methods. The antibody was able to detect PYLCIV-Bgr from infected plants up to dilution 1/16,384 and cross reaction was not observed with Cucumber mosaic virus (CMV), Tobacco mosaic virus (TMV), and Chilli veinal mottle virus (ChiVMV). Positive reaction was readily detected in membrane containing Begomovirus samples from Yogyakarta (Kaliurang and Kulonprogo) and West Java (Bogor and Segunung). Infection of PYLCIV-Bgr in chillipepper, tomato, and Ageratum conyzoides was also confirmed using polyclonal antibody for PYLCIV-Bgr in DIBA. Polyclonal antibody for PYLCIV-Bgr is suggested to be included in disease management approach due to its good detection level.

• Korean Journal Plant Pathology
• /
• v.11 no.3
• /
• pp.224-229
• /
• 1995

Occurrence and incidences of major diseases of peach (Prunus persicae pv. vulgaris), leaf curl caused by Taphrina deformans, bacterial shot hole caused by Xanthomonas campestris pv. pruni, brown rot caused by Monilinia fructicola, and anthracnose caused by Glomerella cingulata in peach orchards in Cheongdo and Kyungsan areas of Gyeongbuk province, Korea, were investigated for four years from 1990 to 1993. In leaf curl and bacterial shot hole which mainly occurred on leaves, frist disease occurrences were dated from late April to early May. The maximum leaf curl incidence was dated in mid May, while dates of the maximum bacterial shot hole incidence varied from mid May to mid August depending on the years surveyed. In brown rot and anthracnose on fruit, the first disease occurrence dates ranged from early June to early August; however, the maximum disease incidences for both were invariably dated in late August. The disease incidences on the dates of the maximum incidences differed year by year, and the averages for the 4 years were 13.2%, 10.5%, 10.9% and 3.8% for leaf curl, bacterial shot hole, brown rot and anthracnose, respectively. Especially in the leaf curl disease, the first disease occurrence dates and the maximum disease incidences matched with the amounts of precipitation of rain up to April, suggesting that the disease occurrence may be related to the precipitation during the early season. The occurrence of leaf curl was somewhat higher in cultivar“Baekmi”than other cultivars. All of the major disease occurred more in hilly orchards than in plain ones.

• Journal of agriculture & life science
• /
• v.50 no.4
• /
• pp.249-253
• /
• 2016

Aster glehni Franchet et Schmidt is a compositae plant and has been known as a native specie in Ulleung Island, Korea. It is officially recognized as a regional specialty that grows only in this region. In 2014, brown and dark spots were observed on aster leaves in a forest research field, Jinju, Korea. A causal agent was isolated from the disease symptomatic leaves and identified as fungus Alternaria solani. Fungal morphological characteristics and molecular identification with internal transcribed spacer sequences were synchronized as A. solani. The isolated fungi reproduced the same disease symptoms when the fungus was artificially inoculated on healthy aster leaves. This is the first report that A. solani caused leaf blight disease in Aster glehni in Korea.

• The Plant Pathology Journal
• /
• v.19 no.4
• /
• pp.189-194
• /
• 2003

The effects of prochloraz on membrane permeability and germination of uredospores of Puccinia recondita were investigated to determine its potential mode of action on wheat leaf rust control activity. Disease control activity of ergosterol biosynthesis inhibitors (EBIs) and their activities on uredospore membrane permeability and germination were examined with wheat leaf rust pathogen, both in vitro and in vivo. While wheat leaf rust was not controlled by prochloraz, electrolytic leakage and spore germination of P. recondita uredospore was the highest with the use of prochloraz among the eight fungicides tested. Prochloraz stimulated uredospore of P. recondita to germinate at a higher ratio. Although certain EBIs, such as hexaconazole, showed excellent control activity, their effects on uredospore membrane permeability and germination was much inferior to prochloraz. Therefore, results of this study suggest that effects of EBIs on membrane permeability and germination of uredospore are not always correlated with their disease control activity.

• Korean Journal Plant Pathology
• /
• v.11 no.3
• /
• pp.217-223
• /
• 1995

Nature of graft transmissibility of pear abnormal leaf spot disease was examined by various grafting methods in the greenhouse and field. When the diseased and symptomless twigs were collected in winter and grafted in the next spring to the seed-originated healthy root stock, the abnormal leaf spot was developed only in the case of the diseased twigs. Double grafting on a seed-originated healthy root stock, where the diseased and the symptomless twigs were used as 1st and 2nd scions, respectively, developed abnormal leaf spot lesions without exception on the 2nd scions. Tongue-graft with the diseased and the symptomless trees also incited abnormal leaf spots on the both trees. Abnormal leaf spots of were also developed on HN-39, an indicator pear tree, used as a 2nd scion in a double graft test, where the diseased twig and a seed-originated healthy tree were used as the 1st scion and the root stock, respectively. When the diseased twig was top-grafted to the healthy root stock, lesion development of abnormal spot was limited to the grafted twig itself in the 1st year, but expanded to the main branches in the 2nd year, and spread over the whole tree in the 3rd year. This result indicates that the causal agent of abnormal leaf spot disease is transmitted by graft.

• Mycobiology
• /
• v.46 no.2
• /
• pp.168-171
• /
• 2018

In 2016, a severe leaf spot disease was found on Iris ensata Thumb. in Nanjing, China. The symptom was elliptical, fusiform, or irregularly necrotic lesion surrounded by a yellow halo, from which a small-spored Alternaria species was isolated. The fungus was identified as Alternaria iridiaustralis based on morphological characteristics. The pathogenicity tests revealed that the fungus was the causal pathogen of the disease. Phylogenic analyses using sequences of ITS, gpd, endoPG, and RPB2 genes confirmed the morphological identification. This study is the first report of A. iridiaustralis causing leaf spots on I. ensata in China.