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

Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 247-254 ◽  
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.

Diagnostic Guide for Gummy Stem Blight and Black Rot on Cucurbits

2013 ◽  
Vol 14 (1) ◽  
pp. 35 ◽  
Author(s):  
Anthony P. Keinath
Keyword(s):  
Fruit Rot ◽  
Black Rot ◽  
Fruiting Bodies ◽  
Didymella Bryoniae ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Foliar Blight ◽  
Stem Cankers

Gummy stem blight and black rot affect all commonly cultivated cucurbits, including melon, watermelon, cucumber, pumpkin, and squash. Symptoms may be found on all vegetative and reproductive parts of plants, although there is variation in susceptibility among species and horticultural types. Characteristic symptoms include foliar blight, crown and stem cankers, and fruit rot. The pathogen, Didymella bryoniae, can be identified from its fruiting bodies of pycnidia and pseudothecia on diseased tissue and in culture. Accepted for publication 27 August 2013. Published 24 October 2013.

scholarly journals Baseline Sensitivity of Didymella bryoniae to Cyprodinil and Fludioxonil and Field Efficacy of these Fungicides Against Isolates Resistant to Pyraclostrobin and Boscalid

Plant Disease ◽  
2015 ◽  
Vol 99 (6) ◽  
pp. 815-822 ◽  
Author(s):  
Anthony P. Keinath
Keyword(s):  
South Carolina ◽  
Citrullus Lanatus ◽  
Control Treatment ◽  
Didymella Bryoniae ◽  
Water Control ◽  
Baseline Sensitivity ◽  
Qoi Fungicides ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Development Of Resistance

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.

scholarly journals Resistance to Gummy Stem Blight in Muskmelon

HortScience ◽  
1993 ◽  
Vol 28 (9) ◽  
pp. 930-931 ◽  
Author(s):  
D.J. McGrath ◽  
L. Vawdrey ◽  
I.O. Walker
Keyword(s):  
Cucumis Melo ◽  
Didymella Bryoniae ◽  
Disease Reaction ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Alternative Sources

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.

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

HortScience ◽  
1997 ◽  
Vol 32 (1) ◽  
pp. 117-121 ◽  
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.

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

1994 ◽  
Vol 34 (8) ◽  
pp. 1191 ◽  
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.

scholarly journals Inheritance of Resistance to Gummy Stem Blight in Watermelon

HortScience ◽  
2017 ◽  
Vol 52 (11) ◽  
pp. 1477-1482 ◽  
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.

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

Plant Disease ◽  
1997 ◽  
Vol 81 (11) ◽  
pp. 1331-1331 ◽  
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.

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

HortScience ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 215-221 ◽  
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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