• Research in Plant Disease
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• v.11 no.2
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• pp.106-114
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• 2005

To breed powdery mildew resistant varieties, 104 accessions of Cucurbita spp. germplasm were evaluated. Powdery mildew resistance and horticultural characteristics of the accessions were investigated in the field conditions. C. martinezii was selected for high resistance to powdery mildew in the field. The growth of powdery mildew pathogen and response of leaf surface tissue to the pathogen were observed after artificial inoculation to resistant C martinezii and susceptible C. moschata cv. 'Wonye No.402'. Mycelium growth was very clearly different between resistant C. martinezii and susceptible C moschata cv. 'Wonye No. 402' at 5 days after inoculation at the adult stage. Interspecific hybridization was attempted to transfer powdery mildew resistance gene(s) from C. martinezii to C. moschata. A single dominant gene action was postulated as deter mining powdery mildew resistance at the seedling stage. But for the effective selection of powdery mildew resistant individuals, it was established that adult plant resistance should be confirmed in the field conditions after the seedling test. Through the seedling and field tests, C. moschata lines resistant to powdery mildew and superior to horticultural characteristics, were selected after 2 backcrossing and 3 selfing generations. The fruit characteristics of newly developed lines were similar to those of the recurrent parent, 'Jaechenjarae'.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.1-5
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• 2011

A new powdery mildew resistant squash (Cucurbita moschata Duch.) 'Miso' was bred from a cross between powdery mildew resistant true variety 'Sangol' and powdery mildew susceptible inbred line 'Seoulmadi' at National Institute of Horticultural & Herbal Science (NIHHS). The 'Miso' variety was vigorous and highly resistant to powdery mildew. It showed white green fruit color. The variety yielded 21.3MT/ha which is 52% more than control variety.

• The Plant Pathology Journal
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• v.36 no.2
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• pp.111-120
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• 2020

Powdery mildew of Indian mustard (Brassica juncea), caused by Erysiphe cruciferarum, is emerging as major problem in India. All the Indian mustard cultivars presently grown in India are highly susceptible to powdery mildew and so far no resistance source has been reported. In this study, with an aim to identify resistant source, 1,020 Indian mustard accessions were evaluated against E. cruciferarum PMN isolate, at Wellington, The Nilgiris, Tamil Nadu, India under natural hot spot conditions. The study identified one accession (RDV 29) with complete resistance against E. cruciferarum PMN isolate for the first time, which was consistent in five independent evaluations. Genetic analysis of F₁, F₂ and backcross populations obtained from the cross RSEJ 775 (highly susceptible) × RDV 29 (highly resistant) for two season revealed that the resistance is governed by two genes with semi-dominant and gene dosage effect. Further, a new disease rating system using six scales (0, 1, 2, 3, 4, and 5) has also been proposed in this study to score powdery mildew based on progress of fungal growth in different plant parts of the F₂ population. The outcome of this study viz. newly identified powdery mildew-resistant Indian mustard accession (RDV 29), information on inheritance of resistance and the newly developed disease rating scale will provide the base for development of powdery mildew-resistant cultivars of Indian mustard.

• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.1
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• pp.35-39
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• 2006

Fifty-six indigenous and twenty nine exotic mulberry varieties were screened against powdery mildew, Myrothecium leaf spot, Pseudocercospora leaf spot, sooty mold and bacterial leaf spot for a period of three years under field condition. The percent disease index (PDI) was recorded during peak season of the foliar diseases. Out of eighty-five varieties studied, ten varieties were highly resistant and eight were resistant to powdery mildew; six varieties were immune and seventy-eight varieties were highly resistant to Myrothecium leaf spot; sixty varieties were highly resistant and 21 were resistant to Pseudocercospora leaf spot; forty four varieties were highly resistant to sooty mold and two varieties were immune and fifty-eight were highly resistant to bacterial leaf spot. Lowest cumulatative disease index was observed in M. multicaulis (7.28) followed by Thailand lobed (7.85) and Italian mulberry (8.06).

• Research in Plant Disease
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• v.18 no.1
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• pp.29-34
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• 2012

Powdery mildew and root-knot nematode are very important diseases occurred in cucurbits. This study was conducted to evaluate the resistance of commercial cucurbit cultivars (21 cultivars of cucumber, 9 cultivars of watermelon, 7 cultivars of oriental melon, and 2 cultivars of melon) to powdery mildew and root-knot nematode. At 60 days after transplanting, disease severity of powdery mildew of commercial cucurbit cultivars was investigated. Two cucumber cultivars, 'Gangryeogsamcheok' and 'Sunhobaegchimdadagi' were moderately resistant but the rest of cucumber cultivars were susceptible to powdery mildew. All examined watermelon and oriental melon cultivars were susceptible to powdery mildew, while two melon cultivars ('PMR Turbo' and 'PMR Victory') were resistant. At 45 days after inoculation of seedlings, disease severity of root-knot nematode of commercial cucurbit cultivars were investigated. One cucumber cultivars, 'Baegbongdadagi' was moderately resistant and the others were susceptible to root-knot nematode. In case of watermelon, 'Dalgonakkul' was resistant and the others were moderately resistant or susceptible to root-knot nematode. All examined oriental melon and melon cultivars were susceptible to root-knot nematode. On these results, we recommend that resistant cultivars to powdery mildew and/or root-knot nematode will be more suitable in cultivation of cucurbits for organic farming.

• Research in Plant Disease
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• v.22 no.3
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• pp.133-144
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• 2016

Powdery mildew (Podosphaera xanthii) causes severe damage to pumpkin crops grown in open fields and plastic house. Initially, we used ten accessions of pumpkin species; Cucurbita pepo (3), C. maxima (2), C. moschata (2), and C. argyrosperma (3) to study the disease progress in different stages of seedling development. Commercial pumpkin varieties were used as susceptible host for inoculum management and young seedlings were inoculated by dusting powdery mildew spores on the cotyledons, 1-true-leaf and 2-true-leaf seedling stages. Based on initial study, we further evaluated 218 pumpkinaccessions for their resistance to powdery mildew in different seedling stages under plastic house. Area under disease progress curve (AUDPC) and relative AUDPC (rAUDPC) was higher in cotyledonary and 1-true-leaf than 2-true-leaf stage. Seedlings at cotyledons and 1-true-leaf seedling stage displayed more susceptibility to powdery mildew. Based on evaluation of 2-true-leaf stage, IT 110859 and IT 278459 from C. pepo and C. argyrosperma identified as resistant (<0.2). Of the 228 pumpkin accessions, 21 (9.2%) pumpkin accessions consisting of C. pepo (2), C. maxima (5), C. moschata (13), and C. argyrosperma (1) exhibited intermediate resistance (<0.4) to powdery mildew and these accessions are useful to growers for its rational management.

• Journal of Plant Biotechnology
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• v.42 no.4
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• pp.284-289
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• 2015

Powdery mildew (Podosphaera xanthii) commonly occurs in cultivated fields of melon (Cucumis melo L.). It inflicts a lot of damages. Therefore, breeding resistant lines is essential. Development of a resistant line by integrating resistance gene takes a long time. In addition, break down of developed resistance by generating new virulent fungus strains increases disease susceptibility. This phenomenon was related to races of powdery mildew. Therefore, it is important to develop a DNA marker to genetically analyze race-specific resistance genes of melon powdery mildew to breed resistant lines. To date, a total of 28 races of Podosphaera xanthii have been reported in the literature. In Japan, 10 races have been reported in the Ibaraki region. We developed a system to characterize the races of Podosphaera xanthii and confirmed eight out of those 10 races in the Ibaraki region. In Korea, only one race has been characterized to date. However, some different races were detected. Through genetic analysis of resistant lines and susceptible lines of powdery mildew, resistance genes of race1 (Pm-X, PXB, and Pm-R 1), race N1 (PXA), race 2 (Pm-w and Pm-R 2), race 3 (Pm-X3), and race 5 (Pm-X5 and Pm-R5) were identified in melon. These related genes of race 1, 3, N1, 5, and race 1, 2, 5 were located at linkage group II and V, respectively. In race 1, resistance gene was located in the linkage group XII. In addition, each race-specific marker related to specific resistance gene was developed. Using race information and race selection system obtained in this study, resistant line can be bred to develop resistant cultivar for several areas. Furthermore, this will make it more easily and economically to breed resistant lines by using selected markers.

• Journal of Plant Biotechnology
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• v.43 no.1
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• pp.58-65
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• 2016

Powdery mildew is an important disease of the melon (Cucumis melo L.). Seven isolates of powdery mildew fungi were collected from five locations in Korea; Anseong (DH487), Icheon (BN103, BN625, BN968), Yeongam (YA141), Changnyeong (CN582), and Suncheon (SN102). All 7 fungi had a similar trend of conidial chain and conidiophore development as Podosphaera xanthii with fibrosin bodies in mature conidia. Among them, 2 isolates of powdery mildew fungi; CN582 and SN102 showed similar responses to resistance against powdery mildew as the previously reported race 1 and race N2. The isolates YA141 and BN103 showed similar responses as like as race A. However, three isolates of powdery mildew fungi (BN625, BN968, and DH487) showed different responses compared to the previously reported races (1, N1, N2, A, S, and 5). Therefore, these three isolates could be designated as new races in melon. Nine out of 15 commercial melon cultivars in Korea showed resistance to race 1 (CN582). However, the new race BN968 invaded all 15 cultivars. Results of the two molecular markers were consistent in response to disease development by race 1 of Podosphaera xanthii in case of the above mentioned cultivars. This study confirmed the presence of new melon powdery mildew fungi in Korea which are similarly notorious as like as the previously reported race 1. Therefore, breeders can use these two molecular markers for breeding melon in Korea that is resistant to race 1 and as well as to some other races.

• The Plant Pathology Journal
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• v.37 no.2
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• pp.115-123
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• 2021

The purpose of this study was to determine the virulence structure of oat powdery mildew (Blumeria graminis f. sp. avenae, Bga) populations in Poland collected in 2014 and 2015. Powdery mildew isolates were collected from 18 locations in Poland. In total, nine lines and cultivars of oat, with different mildew resistance genes, were used to assess virulence of 180 isolates. The results showed that a significant proportion of the Bga isolates found in Poland were virulent to differentials with Pm1, Pm3, Pm6, and Pm3 + Pm8 genes. In contrast Pm4, Pm5, Pm2, and Pm7 genes were classified as resistant to all pathogen isolates used in the experiment. Based on obtained results we can state that there are differences in virulence pattern and diversity parameters between sites and years, but clear trends are not deducible.

• Research in Plant Disease
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• v.14 no.2
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• pp.95-101
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• 2008

Fungicide resistance of cucumber powdery mildew was screened among the pathogens isolated from diseased plants in main cucumber productuion areas in Gyeonggi Province. Each fungicide from different activity group for the control of powdery mildew were sprayed on cucumber leaves according to application concentration. Each conidia mixed with sterilized water isolated of pathogens were transferred on the cucumber leaf disks treated with each fungicide. At 7 to 9 days after inoculation of pathogen, disease severity was recorded under the microscope. Most of pathogen isolates showed moderate resistance to difenoconazole belonged to DMI group fungicide while some isolates from Osan were resistant even $300{\mu}g/ml$. Isolates from Pyeongtaek, Osan and Yongin area also showed moderate resistance to fenarimol while one isolate showed resistant to fenarimol even $300{\mu}g/ml$. Most of isolates from Pyeongtaek, Osan and Yongin showed highly resistant to azoxystrobin belonged to strobilurin group fungicide. Standard sensitive isolates the minimum inhibition concentration(MIC) value for azoxystrobin showed $200{\mu}g/ml$ while resistance isolates showed above $2000{\mu}g/ml$. Resistant isloates also showed cross resistance among strobilurin group fungicides and low control efficacy in the field test. These results suggest that treatment of strobilurin fungicides should be reduced for the control of powdery mildew.