Identification and characterization of Didymella bryoniae causing gummy stem blight disease of watermelon (Citrullus lanatus) in Turkey

To prevent yield reductions from gummy stem blight, fungicides often must be applied to watermelon (Citrullus lanatus) and muskmelon (Cucumis melo). Didymella bryoniae, the ascomycete fungus that causes gummy stem blight, is resistant to thiophanate-methyl, quinone-outside inhibitors (QoI), boscalid, and penthiopyrad. In place of these fungicides, premixtures of cyprodinil and fludioxonil (Switch 62.5WG) or cyprodinil and difenoconazole (Inspire Super 2.82SC) are used. The objectives of this study were to examine baseline isolates of D. bryoniae for sensitivity to cyprodinil and fludioxonil and to determine the efficacy of cyprodinil-fludioxonil and cyprodinil-difenoconazole against isolates resistant to QoI fungicides and boscalid. Colony diameters of 146 isolates of D. bryoniae collected in South Carolina and other U.S. states prior to 2008 were measured on glucose minimal medium amended with cyprodinil or fludioxonil. Mean effective concentration values that reduced relative colony diameter by 50% were 0.052 and 0.099 mg/liter cyprodinil and fludioxonil, respectively. In autumn 2008, 2009, and 2011, field-grown watermelon inoculated with isolates resistant to QoI fungicides and boscalid was treated with boscalid-pyraclostrobin alternated with chlorothalonil, cyprodinil-fludioxonil alternated with chlorothalonil, cyprodinil-difenoconazole alternated with chlorothalonil, tebuconazole alternated with chlorothalonil, chlorothalonil, or water. In 2008 and 2011, both cyprodinil treatments reduced disease severity compared with the water control treatment and chlorothalonil alone. In 2008 and 2009, cyprodinil-fludioxonil reduced severity compared with boscalid-pyraclostrobin and, in 2008, cyprodinil-difenoconazole and tebuconazole also did. Use of cyprodinil-fludioxonil should control gummy stem blight effectively and may delay development of resistance to cyprodinil and fludioxonil in D. bryoniae. However, because Botrytis cinerea became resistant to both cyprodinil and fludioxonil after multiple applications of cyprodinil-fludioxonil per season, prudent fungicide rotations should be followed when using cyprodinil-containing fungicides against D. bryoniae.

Download Full-text

Efficacy of Fungicides and Culture Filtrate of Native Bioagents against Didymella bryoniae Causing Gummy Stem Blight Disease in Gherkin

International Journal of Pure & Applied Bioscience ◽

10.18782/2320-7051.6054 ◽

2018 ◽

Vol 6 (1) ◽

pp. 1122-1132

Author(s):

H. Garampalli ◽

Keyword(s):

Culture Filtrate ◽

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

Blight Disease

Download Full-text

Inheritance of Resistance to Gummy Stem Blight in Watermelon

HortScience ◽

10.21273/hortsci12123-17 ◽

2017 ◽

Vol 52 (11) ◽

pp. 1477-1482 ◽

Cited By ~ 8

Author(s):

Gabriele Gusmini ◽

Luis A. Rivera-Burgos ◽

Todd C. Wehner

Keyword(s):

Citrullus Lanatus ◽

Single Gene ◽

Genetic System ◽

The United States ◽

Inheritance Of Resistance ◽

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

Mendelian Gene ◽

Production Areas

Gummy stem blight (GSB), caused by three related species of Stagonosporopsis [Stagonosporopsis cucurbitacearum (syn. Didymella bryoniae), Stagonosporopsis citrulli, and Stagonosporopsis caricae], is a major disease of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] in most production areas of the United States. We studied the inheritance of resistance to GSB using three PI accessions of watermelon. Four families of six progenies (Pr, Ps, F1, F2, BC1Pr, and BC1Ps) were developed from four crosses of resistant PI accessions by susceptible cultivars. Each family was tested in 2002 and 2003 in North Carolina under field and greenhouse conditions for resistance to GSB. Artificial inoculation was used to induce uniform and strong epidemics. The effect of the Mendelian gene for resistance, db, was tested. Partial failure of the data to fit the single-gene inheritance suggested that resistance to GSB of PI 482283 and PI 526233 may be under the control of a more complex genetic system.

Download Full-text

First Report of Gummy Stem Blight, Caused by Didymella bryoniae, on Watermelon Transplants in California

Plant Disease ◽

10.1094/pdis.1997.81.11.1331b ◽

1997 ◽

Vol 81 (11) ◽

pp. 1331-1331 ◽

Cited By ~ 19

Author(s):

S. T. Koike

Keyword(s):

Citrullus Lanatus ◽

Potato Dextrose Agar ◽

Fruiting Bodies ◽

Didymella Bryoniae ◽

Dark Cycle ◽

Disease Symptoms ◽

Stem Blight ◽

Gummy Stem Blight ◽

Cucumber Fruit ◽

Phoma Cucurbitacearum

In 1997, greenhouse-produced transplants of watermelon (Citrullus lanatus) developed water-soaked lesions on leaf petioles and main stems. As disease progressed, petioles and stems became necrotic and shriveled, and exuded a sticky, translucent tan liquid. Symptoms spread to leaves, which wilted and collapsed. Affected transplants eventually died. Although fruiting bodies were not observed on diseased plants, a fungal agent was consistently isolated from symptomatic tissues. When incubated under lights (12 h light/12 h dark cycle), isolates on potato dextrose agar produced numerous pycnidia with hyaline, cylindrical, one-septate conidia with mean dimensions of 5.6 × 2.8 μm. Under the same incubation conditions, isolates on V8 juice agar produced sparse ostiolate pseudothecia with bitunicate asci and hyaline, oval, one-septate ascospores with mean dimensions of 12.0 × 4.0 μm. Based on these characters, the isolates were identified as Didymella bryoniae (anamorph Phoma cucurbitacearum) (1,2). Pathogenicity was tested by producing conidial inocula of representative isolates and inoculating wounded cotyledons, true leaves, and petioles of watermelon (cv. Sangria), and wounded true leaves and petioles of cucumber (Cucumis sativus cv. Premier Hybrid) (3). Sterile, distilled water was applied to corresponding wounded tissues of control plants. All plants were kept in a humid chamber for 4 days. After 6 (watermelon) to 10 (cucumber) days, inoculated plants exhibited water-soaked lesions followed by necrosis, petiole and leaf wilting, and shriveling of tissues. Pycnidia were observed on cucumber plants after 18 days. The pathogen was reisolated from all inoculated plants and identified as D. bryoniae. Control plants developed no disease symptoms. In addition, agar plugs colonized with the watermelon isolates were placed onto cucumber fruit that were wounded slightly with a sterile scalpel. Fruit were incubated at 22 to 24°C in humid chambers and after 2 days sunken, circular lesions developed. The same pathogen was reisolated from the margins of fruit lesions. Wounded control fruit received sterile agar plugs and did not develop any symptoms. This is the first documentation of gummy stem blight on watermelon transplants in California. References: (1) W. F. Chiu and J. C. Walker. J. Agric. Res. 78:81, 1949. (2) A. P. Keinath et al. Phytopathology 85:364, 1995. (3) A. J. Wyszogrodzka et al. Euphytica 35:603, 1986.

Download Full-text

Genetic Characterization of Didymella bryoniae Isolates Infecting Watermelon and Other Cucurbits in Florida and Georgia

Plant Disease ◽

10.1094/pdis-04-14-0341-re ◽

2015 ◽

Vol 99 (11) ◽

pp. 1488-1499 ◽

Cited By ~ 8

Author(s):

Binoy Babu ◽

Yonas W. Kefialew ◽

Ping-Fang Li ◽

Xing-Ping Yang ◽

Sheeja George ◽

...

Keyword(s):

Citrullus Lanatus ◽

Random Amplified Polymorphic Dna ◽

Rflp Analysis ◽

Genetic Profile ◽

Its Sequence ◽

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

Its Sequence Analysis ◽

Pcr Rflp

Gummy stem blight caused by Didymella bryoniae (anamorph Phoma cucurbitacearum) is a major fungal disease of watermelon (Citrullus lanatus) and other cucurbits. Thirty-five isolates of Didymella and Phoma spp. associated with symptoms of gummy stem blight on watermelon, Canary melon (Cucumis melo), muskmelon (C. melo), and winter squash (Cucurbita maxima) from Florida and Georgia were characterized based on morphology on agar media, pathogenicity on ‘Melody’ watermelon, the internal transcribed spacer (ITS) sequence of ribosomal DNA (rDNA), random amplified polymorphic DNA (RAPD) analysis, and polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) analysis. All of the isolates were pathogenic on watermelon but differed in virulence. RAPD and ITS sequence analysis indicated genetic variability among the isolates but PCR-RFLP analysis did not show any variability. ITS sequence phylogenetic analysis identified two isolates, DB-05 and DB-33, which had a greater identity to that of D. bryoniae isolates from China (98 to 100% sequence homology) than other isolates from Florida and Georgia (95 to 98%). These two isolates possessed a single nucleotide substitution of A to G at position 131 of the ITS1 region. The study characterized the genetic profile of a collection of D. bryoniae isolates from Florida and Georgia in relation to isolates from other U.S. states and countries.

Download Full-text

Differential Susceptibility of Nine Cucurbit Species to the Foliar Blight and Crown Canker Phases of Gummy Stem Blight

Plant Disease ◽

10.1094/pdis-05-13-0510-re ◽

2014 ◽

Vol 98 (2) ◽

pp. 247-254 ◽

Cited By ~ 15

Author(s):

Anthony P. Keinath

Keyword(s):

Cucumis Melo ◽

Citrullus Lanatus ◽

Differential Susceptibility ◽

Cucurbita Moschata ◽

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

Foliar Blight ◽

Diseased Leaf Area ◽

Stem Cankers

Eighteen cucurbit cultivars representing five genera, nine species, and 17 horticultural types were inoculated with Didymella bryoniae in field plots in Charleston, SC, in autumn 2008, autumn 2009, and spring 2011 to determine susceptibility to gummy stem blight. In each year, gummy stem blight cankers occurred more frequently on crowns or main stems of ‘Athena’ muskmelon (Cucumis melo) and ‘Green Striped Cushaw’ squash (Cucurbita argyrosperma) than on all other cultivars except ‘Rocio’ honeydew (Cucumis melo) in 2009, and bottle gourd (Lagenaria siceraria) and Ojakkyo citron (Citrullus lanatus var. citroides) in 2011. Cucurbita moschata was highly resistant to stem cankers. Severity of gummy stem blight on foliage was moderate to severe in autumn 2009, mild to severe in autumn 2008, and very mild in spring 2011 (due to unusually dry weather). Watermelon (Citrullus lanatus var. lanatus) and melon were the most susceptible to foliar blight in 2008 and 2009. In all 3 years, ‘Cheese’ and ‘Bugle’ squash (both Cucurbita moschata), and ‘Judgment III’ and ‘Lioness’ summer squash (C. pepo) were among the cultivars with the least diseased leaf area. C. moschata, C. pepo, C. maxima, and Luffa cylindrica (smooth loofah) were significantly less susceptible to foliar blight than Cucumis melo and three Citrullus lanatus cultivars in 2008 and 2009. This study also is the first documentation of susceptibility of Cucurbita argyrosperma to gummy stem blight.

Download Full-text

First Report of Benomyl Resistance in Didymella bryoniae in Delaware and Maryland

Plant Disease ◽

10.1094/pdis.1999.83.3.304b ◽

1999 ◽

Vol 83 (3) ◽

pp. 304-304 ◽

Cited By ~ 11

Author(s):

K. L. Everts

Keyword(s):

New York ◽

South Carolina ◽

Citrullus Lanatus ◽

New York State ◽

Didymella Bryoniae ◽

Potato Dextrose Agar Medium ◽

First Report ◽

Stem Blight ◽

Colony Diameter ◽

Gummy Stem Blight

Gummy stem blight, caused by Didymella bryoniae (Auersw.) Rehm, is the most severe foliar disease of watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai, in eastern Maryland and southern Delaware. The fungicide benomyl is used in combination with chlorothalonil to manage gummy stem blight. Under conducive environmental conditions, yield losses are high even when fields are sprayed weekly. Resistance of D. bryoniae to benomyl has been reported in New York State and South Carolina (1). Gummy stem blight-infected leaves and stems were collected from nine and three fields in Wicomico County, MD, and Sussex County, DE, respectively, in 1996. Infected tissue was also collected from two Wicomico County fields in 1997. One single-spore subculture was obtained to represent each field. Agar plugs were taken from actively growing subcultures and inverted on a 25% (quarter strength) potato dextrose agar medium amended with 0 and 33.1 mg of benomyl per liter, the concentration of benomyl that reduced relative colony diameter of four resistant isolates in New York and South Carolina by 50% (1). Two replicate plates were used per experiment and each experiment was repeated once. After 6 days of growth at 21°C in the dark, the colony diameter was measured. Isolates were classified as sensitive if they were unable to grow, moderately sensitive if colony diameter was reduced 40 to 60%, and resistant if colony diameter was reduced less than 10% on the benomyl-amended media, compared with unamended media. Isolates that had previously been tested were used as sensitive (W03) and moderately sensitive (NY1) standards (1). In 1996, two isolates were sensitive, four isolates were moderately sensitive, and six isolates were resistant to benomyl. One isolate from 1997 was resistant and the other was moderately sensitive. This is the first report of resistance to benomyl within the D. bryoniae population in eastern Maryland and southern Delaware. Reference: (1) A. P. Keinath and T. A. Zitter. Plant Dis. 82:479, 1998.

Download Full-text

The First recording of Gummy Stem Blight Disease Caused by Didymella bryoniae(Stagonosporopsis cucurbitacearum ) on Watermelon Crop in Iraq

10.36295/asro.2020.231619 ◽

2020 ◽

Vol 23 (16) ◽

Author(s):

Farouk Hussein Khudair Al-Jubouri ◽

Halima Zughair Hussain

Keyword(s):

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

Blight Disease

Download Full-text

First Report of Gummy Stem Blight Caused by Didymella bryoniae on Watermelon and Confirmation of the Disease on Pumpkin in Tanzania

Plant Disease ◽

10.1094/pdis-01-11-0044 ◽

2011 ◽

Vol 95 (6) ◽

pp. 768-768 ◽

Cited By ~ 7

Author(s):

B. D. Jensen ◽

A. Massawe ◽

I. S. Swai

Keyword(s):

Citrullus Lanatus ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Weather Conditions ◽

Fruit Rot ◽

Didymella Bryoniae ◽

First Report ◽

Stem Blight ◽

Gummy Stem Blight ◽

Specific Pcr

Foliar, stem, and fruit lesions were observed on watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) and pumpkin (Cucurbita maxima Duchesne) in two separate research fields in the district of Arusha, Tanzania during the warm, rainy season from February to April 2010. Similar symptoms were observed in commercial watermelon fields and intercropped pumpkin fields in Same and Moshi districts with as much as 100% fruit loss in watermelon. Disease symptoms on watermelon were dark brown, V-shaped leaf lesions. On pumpkin, V-shaped leaf lesions were light brown. On both hosts, stems showed water-soaked lesions after rain, which dried up and cracked. On pumpkin, a gummy, amber exudate was seen after rain on stem and fruit lesions. Flowers and fruits of both hosts developed black rot spots and aborted. Isolation of the causal agent on potato dextrose agar (PDA) from leaf and stem pieces of watermelon and pumpkin plants in Arusha showed white-to-olivaceous green mycelium. Pycnidia formed on one-quarter-strength PDA and produced hyaline, oblong conidia mainly with two guttules, nonseptate, 5 to 11 × 3 to 5 μm. Pathogenicity was tested with three isolates from watermelon and one from pumpkin on four 1-month-old plants per watermelon cvs. Sugar Baby and Charleston Grey and pumpkin cv. Small Sugar per isolate. The test was repeated on the watermelon cultivars. One site on the main stem and two leaves per plant were misted, pricked with a scalpel, inoculated with 3-day-old mycelial plugs (5 × 5 mm), and kept humid at 20 to 30°C in cellophane bags for 3 days. All plants developed leaf and/or stem lesions. Detached, misted leaves were also laid on 2% water agar and inoculated as above. Water-soaked lesions developed around inoculation sites and microscopy of infected tissue revealed pycnidia with conidia as described above. All isolates infected both hosts. A set of control plants and detached leaves, mock inoculated with agar plugs, remained symptomless. The fungus was reisolated from infected leaves and stems of both hosts. On the basis of the morphological characteristics, the fungus was identified as Didymella bryoniae (Auersw.) Rehm (anamorph Phoma cucurbitacearum (Fr.:Fr.) Sacc.) (1,3) and this was confirmed by amplification of species-specific PCR products. The isolates from both hosts were cultured in liquid medium, and DNA was extracted using a DNeasy Plant Mini Kit (Qiagen, Valencia, CA). PCR and multiplex PCR involving D. bryoniae-unique primer sequences D6 and D7S, in combination with primer UNLO28S22, produced the expected band sizes (2). To our knowledge, this is the first report of gummy stem blight and black fruit rot of watermelon caused by D. bryoniae in Tanzania, which confirms a previous report of leaf spot on pumpkin (4), and the first report of black fruit rot on pumpkin. The disease was previously an unidentified problem in watermelon and the severe outbreak was associated with favorable weather conditions. References: (1) A. P. Keinath et al. Phytopathology 85:364, 1995. (2) C. A. Koch and R. S. Utkhede. Can. J. Plant Pathol. 26:291, 2004. (3) E. Punithalingam and P. Holliday. No. 332 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1972. (4) E. A. Riley. Mycol. Pap. 75:1, 1960.

Download Full-text