scholarly journals Watermelon Fruit Disorders

1999 ◽  
Vol 9 (2) ◽  
pp. 155-161 ◽  
Author(s):  
Donald N. Maynard ◽  
Donald L. Hopkins
Keyword(s):  
Citrullus Lanatus ◽  
Phytophthora Capsici ◽  
Unknown Origin ◽  
Fruit Rot ◽  
Black Rot ◽  
Economic Returns ◽  
Didymella Bryoniae ◽  
Bacterial Fruit Blotch ◽  
Gummy Stem Blight ◽  
Blossom End Rot

Watermelon (Citrullus lanatus [Thunb.] Matsum & Nakai) fruit are affected by a number of preharvest disorders that may limit their marketability and thereby restrict economic returns to growers. Pathogenic diseases discussed include bacterial rind necrosis (Erwinia sp.), bacterial fruit blotch [Acidovorax avenae subsp. citrulli (Schaad et al.) Willems et al.], anthracnose [Colletotrichum orbiculare (Berk & Mont.) Arx. syn. C. legenarium (Pass.) Ellis & Halst], gummy stem blight/black rot [Didymella bryoniae (Auersw.) Rehm], and phytophthora fruit rot (Phytophthora capsici Leonian). One insect-mediated disorder, rindworm damage is discussed. Physiological disorders considered are blossom-end rot, bottleneck, and sunburn. Additionally, cross stitch, greasy spot, and target cluster, disorders of unknown origin are discussed. Each defect is shown in color for easy identification.

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

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 768-768 ◽  
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.

scholarly journals Effect of Fungicide Applications Scheduled to Control Gummy Stem Blight on Yield and Quality of Watermelon Fruit

Plant Disease ◽  
2001 ◽  
Vol 85 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Anthony P. Keinath
Keyword(s):  
Disease Severity ◽  
Fruit Weight ◽  
Fruit Rot ◽  
Soluble Solids ◽  
Black Rot ◽  
Soluble Solids Content ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Yield And Quality ◽  
Solids Content

Yield and quality reductions in watermelon infected with Didymella bryoniae may be attributed to reduced number or weight of fruit, sunburned fruit, fruit rot, or low sugar content due to gummy stem blight on foliage and black rot on fruit. Number, weight, soluble solids content, and external appearance of fruit were determined in four experiments conducted in fall 1996 and 1997 and spring 1997 and 1998. Severity of gummy stem blight was varied by applying no fungicide, mancozeb, or chlorothalonil according to different schedules. In the fall, when disease severity was high, total fruit weight, percent marketable fruit, and soluble solids content were lower and percent fruit with black rot was higher in nonsprayed than in sprayed treatments. Fungicide applications did not affect total fruit weight, soluble solids content, or black rot in the spring, when disease severity was moderate to low. Percent sunburned fruit was greater in treatments sprayed every 14 days than in those sprayed weekly. In fall experiments, the number of healthy, unblemished fruit increased linearly as the number of fungicide applications was increased from zero to nine per season. Yield losses in watermelon to gummy stem blight and black rot resulted primarily from a reduction in total fruit weight and an increase in number of diseased and sunburned fruit.

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 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 Phytophthora Fruit Rot of Watermelon Caused by Phytophthora capsici in U.S. Plant Introductions

HortScience ◽  
2012 ◽  
Vol 47 (12) ◽  
pp. 1682-1689 ◽  
Author(s):  
Chandrasekar S. Kousik ◽  
Jennifer L. Ikerd ◽  
Patrick Wechter ◽  
Howard Harrison ◽  
Amnon Levi
Keyword(s):  
Citrullus Lanatus ◽  
Phytophthora Capsici ◽  
Fruit Rot ◽  
Preliminary Evaluation ◽  
Yield Losses ◽  
Mature Fruit ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Plant Introductions ◽  
Agar Plug

Phytophthora fruit rot, caused by Phytophthora capsici, is prevalent in most watermelon-producing regions of southeastern United States and is known to cause pre- and post-harvest yield losses. A non-wound inoculation technique was developed to evaluate detached mature fruit belonging to U.S. watermelon PIs for resistance to fruit rot caused by P. capsici. Mature fruit were harvested and placed on wire shelves in a walk-in humid chamber [greater than 95% relative humidity (RH), temperature 26 ± 2 °C] and inoculated with a 7-mm agar plug from an actively growing colony of P. capsici. Twenty-four PIs that exhibited resistance in a preliminary evaluation of 205 PIs belonging to the watermelon core collection in 2009 were grown in the field and greenhouse in 2010 and 2011 and evaluated in the walk-in humid chamber. Fruit rot development was rapid on fruit of susceptible controls ‘Black Diamond’, ‘Sugar Baby’, and PI 536464. Several accessions including PI 560020, PI 306782, PI 186489, and PI 595203 (all Citrullus lanatus var. lanatus) were highly resistant to fruit rot. One C. colocynthis (PI 388770) and a C. lanatus var. citroides PI (PI 189225) also showed fruit rot resistance. Fruit from PIs that were resistant also had significantly lower amounts of P. capsici DNA/gram of fruit tissue compared with the susceptible commercial cultivars Sugar Baby and Black Diamond. The sources of resistance to Phytophthora fruit rot identified in this study may prove useful in watermelon breeding programs aimed at enhancing disease resistance.

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

2016 ◽  
Vol 90 ◽  
pp. 150-156 ◽  
Author(s):  
Esin Basım ◽  
Hüseyin Basım ◽  
Muntala Abdulai ◽  
Derya Baki ◽  
Nurhan Öztürk
Keyword(s):  
Citrullus Lanatus ◽  
Didymella Bryoniae ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Blight Disease ◽  
Identification And Characterization

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

Plant Disease ◽  
2015 ◽  
Vol 99 (11) ◽  
pp. 1488-1499 ◽  
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.

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.

Sign in / Sign up

Export Citation Format

Share Document