scholarly journals Reproduction of Didymella bryoniae on Nine Species of Cucurbits Under Field Conditions

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1379-1386 ◽  
Author(s):  
Anthony P. Keinath
Keyword(s):  
Environmental Conditions ◽  
Cucumis Melo ◽  
Citrullus Lanatus ◽  
Lagenaria Siceraria ◽  
Cucurbita Maxima ◽  
Fruiting Bodies ◽  
Didymella Bryoniae ◽  
Plant Parts ◽  
Gummy Stem Blight ◽  
Field Plots

Eighteen cucurbit cultivars representing 5 genera, 9 species, and 11 taxa susceptible to gummy stem blight were inoculated with Didymella bryoniae in field plots in Charleston, SC, in autumn 2008, autumn 2009, and spring 2011 to determine the suitability of the hosts and various plant parts for formation of sexual and asexual fruiting bodies of the pathogen. In 1, 2, or 3 years, D. bryoniae reproduced on all 18 cultivars, on leaves, and on all plant parts examined—pedicles, peduncles, petioles, tendrils, and vines. Watermelon and citron (both Citrullus lanatus) and melon (Cucumis melo) had significantly more leaves with fruiting bodies than cucumber (Cucumis sativus), bottle gourd (Lagenaria siceraria), and eight cultivars of squash and pumpkin (Cucurbita maxima, C. moschata, and C. pepo). On plant parts other than leaves, melon had the greatest proportions of tissue pieces with fruiting bodies, and citron had the least. Fruiting bodies were observed on 86% of plant parts examined in autumn 2009 but on only 28% in spring 2011, when environmental conditions were hot and dry. In 2009, pseudothecia and pycnidia were found in equal proportions on leaves, but pseudothecia were found more frequently than pycnidia on leaves in 2011 and on other plant parts in 2009 and 2011.

scholarly journals Resistência de porta-enxertos de cucurbitáceas a nematóides e compatibilidade da enxertia em melão

2014 ◽  
Vol 32 (3) ◽  
pp. 297-302 ◽  
Author(s):  
Letícia A Ito ◽  
Lucas A Gaion ◽  
Francine S Galatti ◽  
Leila T Braz ◽  
Jaime M Santos
Keyword(s):  
Cucumis Sativus ◽  
Cucumis Melo ◽  
Citrullus Lanatus ◽  
Cucurbita Moschata ◽  
Lagenaria Siceraria ◽  
Cucurbita Maxima ◽  
Luffa Cylindrica ◽  
Benincasa Hispida

Devido ao severo ataque de nematoides na cultura do meloeiro rendilhado sob ambiente protegido, este trabalho teve por objetivo selecionar porta-enxertos resistentes a Meloidogyne incognitae M. javanica. O experimento foi conduzido em casa de vegetação, de outubro de 2010 a abril de 2011, em Jaboticabal-SP. Foram avaliados 33 porta-enxertos; melões: CNPH 01-930 (Cucumis melo var. flexuosus), CNPH 01-962, CNPH 01-963 (Cucumis melo var. conomon), cvs. Gaúcho Redondo, Gaúcho Comprido, Redondo Amarelo, Gulfcoast, Chilton, Bônus n° 2, Fantasy; melancias: cv. Charleston Gray, Progênie da Coréia (Citrullus lanatus); abóboras: cvs. Mra. Ma, Ornamental, Howden, Mammoth, Kururu, Goianinha (Cucurbita moschata); cabaça: Abóbora de Porco, cvs. Maranhão, Brasileirinha (Lagenaria siceraria); moranga: cv. Pataca Gigante (Cucurbita maxima); pepinos: cvs. Caipira, Branco Meio-Comprido, Curumim (Cucumis sativus); buchas: Metro, Semente Branca, Semente Preta (Luffa cylindrica); abóbora d'água (Benincasa hispida); abóbora porta-enxerto: Híbrido cv. Keij; quiabo de Metro (Trichosanthes cucumerins) e Cruá (Sicana odorifera). Para avaliar a resistência de plantas, as mudas foram transplantadas para vasos e inoculados com 3.000 ovos e juvenis de M. incognita via sistema radicular. Aos 50 dias após a inoculação, foi realizada avaliação da resistência das plantas, com base no fator de reprodução do nematoide. Foram realizados os mesmos procedimentos para as duas espécies de nematoides. Nos porta-enxertos resistentes aos nematoides foram realizadas enxertias, com os melões rendilhados 'Bônus n° 2' e 'Fantasy'. CNPH 01-962, CNPH 01-963 e melão 'Gaúcho Redondo' foram resistentes a M. incognita. Melão 'Redondo Amarelo', melancia 'Charleston Gray', Progênie da Coréia, e Trichosanthes cucumerins, foram resistentes a M. javanica. Benincasa hispida foi resistente a ambas as espécies. As compatibilidades de enxertia entre os porta-enxertos resistentes e os melões rendilhados 'Bônus no 2' e 'Fantasy' foram superiores a 98%.

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.

Premix Fungicides that Reduce Development of Fruiting Bodies but not Leaf Lesions by Stagonosporopsis citrulli on Watermelon Leaves in the Field

Plant Disease ◽  
2020 ◽  
Author(s):  
Anthony P. Keinath
Keyword(s):  
Disease Severity ◽  
Fruiting Body ◽  
Citrullus Lanatus ◽  
Fruiting Bodies ◽  
Fruiting Body Formation ◽  
Main Method ◽  
Body Formation ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Field Plots

Fungicide applications are the main method to manage gummy stem blight on watermelon (Citrullus lanatus) and other cucurbits, but it is unknown if fungicides affect development of leaf lesions or fruiting bodies by Stagonosporopsis citrulli. Cyprodinil + fludioxonil (Switch), cyprodinil + difenoconazole (Inspire Super), cyprodinil (Vangard), fludioxonil (Cannonball), and difenoconazole (Inspire) were applied to watermelon in rotation with chlorothalonil (Bravo) in fall 2017, 2018, and 2019. Water and chlorothalonil applied weekly served as control treatments. All fungicides reduced disease severity (percentage of leaf area diseased) and AUDPC in field plots compared to water. Cyprodinil + fludioxonil and cyprodinil + difenoconazole reduced disease severity and AUDPC more than chlorothalonil. Fungicides did not affect the number, diameter, expansion, or area of lesions. All fungicides reduced the number of lesions with fruiting bodies of S. citrulli compared to water (P < 0.05). Cyprodinil + fludioxonil and cyprodinil + difenoconazole reduced the percentage of leaf lesions with fruiting bodies, and the diameter and area of the portions of leaf lesions covered with fruiting bodies, compared to water and chlorothalonil. Premix fungicides containing cyprodinil reduced fruiting body formation by S. citrulli, which may partially explain their efficacy in managing gummy stem blight.

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.

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.

scholarly journals Improvement of Grafted Watermelon Transplant Survival as a Result of Size and Starch Increases Over Time Caused by Rootstock Fatty Alcohol Treatment: Part II

2014 ◽  
Vol 24 (3) ◽  
pp. 350-354
Author(s):  
Shawna L. Daley ◽  
William Patrick Wechter ◽  
Richard L. Hassell
Keyword(s):  
Fatty Alcohol ◽  
Citrullus Lanatus ◽  
Soluble Sugar ◽  
Lagenaria Siceraria ◽  
Energy Reserves ◽  
Cucurbita Maxima ◽  
Stored Energy ◽  
Total Soluble Sugar ◽  
Alcohol Treatments ◽  
Over Time

Fatty alcohol treatments can be used to eliminate the meristem of cucurbit (Cucurbitaceae) rootstocks, which prevents regrowth when grafting, but the effects of the treatment on the rootstock have not been documented. Two rootstock types, ‘Emphasis’ bottle gourd (Lagenaria siceraria) and ‘Carnivor’ interspecific hybrid squash (Cucurbita maxima × C. moschata) commonly used in watermelon (Citrullus lanatus) grafting significantly increased in cotyledon and hypocotyl size over 21 days after treatment (DAT) with a 6.25% fatty alcohol emulsion. There was a significant increase in total soluble sugar (glucose, sucrose, and fructose) content for each rootstock hypocotyl and cotyledon. Starch concentrations of hypocotyls and cotyledons also increased significantly in both rootstocks. This increase in stored energy could greatly increase the success rate of the grafting process. Increased rootstock energy reserves could overcome the need for keeping the rootstock cotyledon intact when grafting.

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.

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