First Report of Pycnidial Stage of Didymella bryoniae, the Causal Fungus of Gummy Stem Blight on Cantaloupe (Cucumis melo var cantalupensis) in Egypt

Resistance to gummy stem blight [Didymella bryoniae (Auersw.) Rehm] was evaluated in two accessions of Cucumis melo L., PI 266935 and PI 266934. Based on disease reaction scores and dry weights, PI 266934 possessed much greater resistance than PI 266935. The quality of resistance of PI 266934 was unaffected by the ranges of seedling ages and inoculum concentrations used. No melon cultivar, to our knowledge, is highly resistant to gummy stem blight in the field, and alternative sources of superior resistance are potentially useful for breeding.

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Screening Melon (Cucumis melo) for Resistance to Gummy Stem Blight in the Greenhouse and Field

HortScience ◽

10.21273/hortsci.32.1.117 ◽

1997 ◽

Vol 32 (1) ◽

pp. 117-121 ◽

Cited By ~ 14

Author(s):

Yiping Zhang ◽

Molly Kyle ◽

Konstantinos Anagnostou ◽

Thomas A. Zitter

Keyword(s):

Cucumis Melo ◽

Field Tests ◽

Plant Introduction ◽

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

High Level ◽

Different Origins ◽

Chinese Group ◽

Onondaga County

Greenhouse and field evaluations of melon (Cucumis melo L.) for resistance to gummy stem blight, caused by the fungus Didymella bryoniae (Auersw.) Rehm, were conducted on 798 U.S. Dept. of Agriculture Plant Introduction (PI) accessions and 24 related Cucumis species. Plants were inoculated at the three to four true-leaf stage with a virulent isolate of D. bryoniae collected from Onondaga County, N.Y., and disease indices were calculated based on foliar and stem symptoms. In greenhouse screens, 43 C. melo accessions showed a high level of resistance. Results were consistent between the optimized greenhouse screening procedure described and inoculated replicated field tests. Of these accessions, a Chinese group, PIs 157076, 157080, 157081, 157082, 157084; another group from Zimbabwe, PIs 482393, 482398, 482399, 482402, 482403, 482408; and some others from different origins, PI 255478 (Korea) and PI 511890 (Mexico), showed high levels of resistance, at least equal to that in PI 140471, the leading source of resistance to date.

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Evaluation of fungicides and cultivars for control of gummy stem blight of rockmelon caused by Didymella bryoniae

Australian Journal of Experimental Agriculture ◽

10.1071/ea9941191 ◽

1994 ◽

Vol 34 (8) ◽

pp. 1191 ◽

Cited By ~ 7

Author(s):

LL Vawdrey

Keyword(s):

Cucumis Melo ◽

The United States ◽

United States Department ◽

Didymella Bryoniae ◽

Department Of Agriculture ◽

States Department ◽

Stem Blight ◽

Gummy Stem Blight ◽

Commercial Cultivars ◽

Marketable Fruit

Ten fungicides were evaluated in 2 experiments with rockmelons for control of gummy stem blight caused by Didymella bryoniae. The fungicides (g a.i./ha) tebuconazole (100 and 160), fentin hydroxide (226), prochloraz Mn (231 and 370), benomyl (400), benomyl (400, 500) plus white oil (2 L/ha), propiconazole (100), mancozeb (1600), mancozeb plus phosphonic acid (1600 + 1000), myclobutanil (237), and chlorothalonil (1600) significantly (P<0.05) reduced the incidence and severity of gummy stem blight compared with an unsprayed treatment. Total weight of fruit and number and weight of marketable fruit in plots treated with fungicides were increased (P<0.05) by as much as 55% compared with untreated plots. Premature fruit ripening was reduced where there was effective disease control. Tebuconazole was the superior chemical but was phytotoxic when applied at 160 g a.i./ha. Fentin hydroxide caused burn on old foliage. Two accessions of Cucumis melo obtained from the United States Department of Agriculture (PI 266934, PI 266935) and 5 commercial cultivars were evaluated for resistance to gummy stem blight in a field experiment. PI 266934 and PI 266935 were highly resistant and the commercial cultivars were susceptible.

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Resistance to Gummy Stem Blight in Melon (Cucumis melo L.) Germplasm and Inheritance of Resistance from Plant Introductions 157076, 420145, and 323498

HortScience ◽

10.21273/hortsci.42.2.215 ◽

2007 ◽

Vol 42 (2) ◽

pp. 215-221 ◽

Cited By ~ 13

Author(s):

Joseph N. Wolukau ◽

Xiao-Hui Zhou ◽

Ying Li ◽

Yong-Bin Zhang ◽

Jin-Feng Chen

Keyword(s):

Cucumis Melo ◽

Dominant Gene ◽

Plant Introduction ◽

Didymella Bryoniae ◽

Genetics Of Resistance ◽

Sources Of Resistance ◽

Resistant Parent ◽

Plant Introductions ◽

Stem Blight ◽

Gummy Stem Blight

Gummy stem blight incited by the fungus Didymella bryoniae is a major disease of melons worldwide. The objectives of the present study were to critically evaluate melon (Cucumis melo L.) germplasm for resistance to D. bryoniae and to characterize the genetics of resistance in the resistant accessions. Two hundred sources of germplasm (plant introduction accessions, cultivars, breeding lines, landraces, and wild relatives) were screened against a single highly virulent isolate (IS25) of D. bryoniae in a plastic tunnel. The genetics of resistance to D. bryoniae was studied in three crosses between plant introductions 157076, 420145, and 323498, resistant parents that were fairly adapted (flowering, fruiting, powdery mildew tolerance) to Nanjing conditions, and plant introductions 268227, 136170, and NSL 30032 susceptible parents, respectively. Six populations of each cross (susceptible parent, resistant parent, F1, F2, the two reciprocal backcrosses) were analyzed for their responses to D. bryoniae. Seedlings in both studies were inoculated with a spore suspension (5 × 105 spores/mL−1) of D. bryoniae at the four to six true-leaf stages and assessed for leaf and stem damage at 7, 14, and 21 d postinoculation. Results of germplasm screening indicated most germplasms reported as resistant elsewhere were confirmed resistant under our conditions. However, some plant introductions identified as highly resistant elsewhere were susceptible under our conditions, the most interesting being plant introduction 482399. This plant introduction that was considered resistant was highly susceptible in our study. We also identified other sources of resistance not reported previously, for example, JF1; a wild Cucumis from the highlands of Kenya was rated highly resistant. Analysis of segregation of F1, F2, and backcross generations of the three crosses indicated that each of the three plant introductions carry a single dominant gene for resistance to the D. bryoniae.

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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.

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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.

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Monogenic Dominant Resistance to Gummy Stem Blight in Two Melon (Cucumis melo) Accessions

Plant Disease ◽

10.1094/pdis.1999.83.12.1105 ◽

1999 ◽

Vol 83 (12) ◽

pp. 1105-1107 ◽

Cited By ~ 14

Author(s):

T. L. Zuniga ◽

J. P. Jantz ◽

T. A. Zitter ◽

M. K. Jahn

Keyword(s):

Cucumis Melo ◽

Dominant Gene ◽

Plant Introduction ◽

Didymella Bryoniae ◽

Susceptible Parent ◽

Stem Blight ◽

Gummy Stem Blight ◽

Backcross Populations ◽

Relationship Of ◽

Cucumis Melo L

Two melon (Cucumis melo L.) accessions, plant introduction (PI) 157082 and PI 511890, reported to be resistant to gummy stem blight, a disease incited by the fungus Didymella bryoniae, were crossed with a susceptible parent to determine the inheritance of resistance. Resistance in both accessions is due to a single dominant gene, based on analysis of F1, F2, and backcross populations. Additionally, PI 157082 was crossed with PI 140471, the other source of resistance identified to date, to examine the genetic relationship of resistance found in these two sources. The frequency of susceptible individuals from the (PI 157082 × 140471) F2 population was consistent with a 15:1 resistant:susceptible ratio, indicating that PIs 140471 and 157082 possess different resistance genes.

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Reaction of melon genotypes to the gummy stem blight and the downy mildew

Horticultura Brasileira ◽

10.1590/s0102-05362009000200007 ◽

2009 ◽

Vol 27 (2) ◽

pp. 160-165 ◽

Cited By ~ 5

Author(s):

Gil R dos Santos ◽

Manoel D de Castro Neto ◽

Leandro N Ramos ◽

Adalberto C Café-Filho ◽

Ailton Reis ◽

...

Keyword(s):

Downy Mildew ◽

Cucumis Melo ◽

Significant Variation ◽

Natural Infection ◽

Pseudoperonospora Cubensis ◽

Didymella Bryoniae ◽

Stem Blight ◽

Gummy Stem Blight ◽

Stem Infection ◽

Leaf Infection

The gummy stem blight (Didymella bryoniae) and the downy mildew (Pseudoperonospora cubensis) are two foremost melon (Cucumis melo) diseases, considering their effects on yield and fruit quality. Despite the importance of such diseases, relatively few studies have been done so far on the identification of resistance sources to D. bryoniae and P. cubensis in Brazil. This work aimed at evaluating the resistance of commercial melon genotypes to the gummy stem blight and the downy mildew. Firstly, the most aggressive and representative D. bryoniae isolate was selected. Subsequently, the resistance of 86 melon genotypes to stem infection was studied upon greenhouse conditions by inoculating with the previously selected isolate. Afterwards, the resistance to mildew and leaf infection by D. bryoniae of 28 melon genotypes was evaluated in the field, under natural infection. In the greenhouse, all 86 melon genotypes were infected and showed stem infection symptoms caused by D. bryoniae four days after inoculation. Nevertheless, a significant variation on the resistance levels of the melon genotypes was found. Under field conditions and natural inoculation, genotypes Taslaki and Sary Juliabi were the most susceptible to leaf infection by D. bryoniae, significantly differing from the other genotypes. The lowest levels of susceptibility were identified in genotypes Perlita Busle S1, Valenciano Elíptico, Glaver, MR1, and 2526. All genotypes were susceptible to the downy mildew, albeit differing in susceptibility levels.

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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.

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