scholarly journals Field Tests for Cucumber Resistance to Gummy Stem Blight in North Carolina

HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 327-329 ◽  
Author(s):  
Todd C. Wehner ◽  
Paul C. St. Amand
Keyword(s):  
North Carolina ◽  
Field Tests ◽  
Plant Introduction ◽  
Lesion Size ◽  
Didymella Bryoniae ◽  
Severe Problem ◽  
Breeding Lines ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
M 12

Gummy stem blight [Didymella bryoniae (Auersw.) Rehm] is the second most important pathogen of field-grown cucumbers (Cucumis sativus L.) in North Carolina and a severe problem for greenhouse-grown cucumbers worldwide. To determine whether resistance exists under North Carolina field conditions, 83 cultigens [cultivars, breeding lines, and plant introduction (PI) accessions] were evaluated in the field for 4 years for their resistance to a mixture of D. bryoniae isolates. Plants were inoculated at the vine tip-over stage and rated for foliar lesion size and number. Cultigens identified as resistant in Wisconsin and The Netherlands were not resistant in North Carolina. When averaged over years and locations, the most resistant C. sativus cultigens were PI 164433, `Slice', PI 390264, M 17, and M 12. Several accessions of related Cucumis species were highly resistant: PI 299568 (C. myriocarpus Naud.), PI 282450 (C. zeyheri Sond.), PI 299572 (C. myriocarpus), and PI 233646 (C. anguria L.). The most susceptible cultivars were `Colet', `Meresto', `Supergreen', `Dura', `Pioneer', `Marketmore 76', `Pickmore', and `Addis'. `Calypso' and `Dasher II', popular cultivars in North Carolina, were moderately susceptible.

scholarly journals Screening the Cucumber Germplasm Collection for Resistance to Gummy Stem Blight in North Carolina Field Tests

HortScience ◽  
2000 ◽  
Vol 35 (6) ◽  
pp. 1132-1140 ◽  
Author(s):  
Todd C. Wehner ◽  
Nischit V. Shetty
Keyword(s):  
North Carolina ◽  
Germplasm Collection ◽  
Field Tests ◽  
Plant Introduction ◽  
Lesion Size ◽  
Didymella Bryoniae ◽  
Breeding Lines ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
And Control

Gummy stem blight (Didymella blight), caused by Didymella bryoniae (Auersw.) Rehm and its anamorph Phoma cucurbitacearum (Fr.:Fr.) Sacc., is the second most important disease of cucumber (Cucumis sativus L.) in North Carolina after root knot nematodes Meloidogyne sp. Both Didymella blight and Phoma blight, caused by Phoma exigua Desm., have similar symptoms and control practices, and are generally referred to as gummy stem blight. In order to determine whether resistance existed to North Carolina isolates of D. bryoniae, 851 cultigens [cultivars, breeding lines, and plant introduction (PI) lines] were evaluated in the field. Plants were inoculated with one selected isolate (highly pathogenic in preliminary greenhouse tests) at the vine tip-over stage. They were rated for foliage lesion size and number on a 0 to 9 visual scale (0 = no disease, 9 = plant killed) and average ratings for 10 plants per plot were analyzed. The ratings ranged from 2.0 (highly resistant) to 8.5 (highly susceptible) with a mean of 6.2. The most resistant breeding lines and PI accessions were PI 200815, PI 390243, `LJ 90430', PI 279469, and PI 432855. The most resistant cultivars were `Homegreen #2', `Little John', `Transamerica', and `Poinsett 76'. The most susceptible cultigens in the study were PI 288238, PI 357843, PI 357865, and PI 167134. Two popular cultivars in North Carolina, `Calypso' and `Dasher II', were moderately resistant.

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.

Boscalid Insensitivity Documented in Didymella bryoniae Isolated from Watermelon in Florida and North Carolina

2012 ◽  
Vol 13 (1) ◽  
pp. 42
Author(s):  
Katherine L. Stevenson ◽  
Anthony P. Keinath ◽  
Anna Thomas ◽  
David B. Langston ◽  
Pamela D. Roberts ◽  
...  
Keyword(s):  
North Carolina ◽  
South Carolina ◽  
High Frequency ◽  
In Vitro Assays ◽  
Didymella Bryoniae ◽  
Triazole Fungicides ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Commercial Mixture

The fungicide Pristine, a commercial mixture of pyraclostrobin and boscalid, has been used widely on watermelon and other cucurbits to control gummy stem blight, caused by the fungus Didymella bryoniae. Since 2007, isolates of D. bryoniae insensitive to boscalid have been found in Georgia, Indiana, and South Carolina. Most isolates of D. bryoniae obtained in 2009 and 2010 from diseased watermelon leaves collected in several counties in Florida and North Carolina were found to be insensitive to boscalid using in vitro assays. Gummy stem blight would not be effectively managed with Pristine in any of the counties where samples were collected due to the high frequency of insensitivity to boscalid. Fortunately growers can instead use several triazole fungicides registered for use on cucurbits since 2009. Accepted for publication 30 March 2012. Published 18 May 2012.

scholarly journals Downy Mildew Resistance of the Cucumber Germplasm Collection in North Carolina Field Tests

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 450B-450
Author(s):  
Todd C. Wehner ◽  
Nischit V. Shetty
Keyword(s):  
North Carolina ◽  
Downy Mildew ◽  
Germplasm Collection ◽  
Field Tests ◽  
Plant Introduction ◽  
Leaf Damage ◽  
Downy Mildew Resistance ◽  
Mildew Resistance ◽  
Breeding Lines ◽  
Production Areas

Downy mildew [Pseudoperonospora cubensis (Berk. & Curt.) Rostov] is an important disease in most cucumber (Cucumis sativus L.) production areas of the world. Resistant cultivars are available, but higher levels are needed if yield losses are to be avoided. The objective of this experiment was to test all available plant introduction accessions, cultivars, and breeding lines (collectively referred to as cultigens) of cucumber for downy mildew resistance under field conditions in North Carolina. Cultigens were tested in 2 years and two replications under natural field epidemics of the disease. Mean ratings for downy mildew leaf damage ranged from 1.3 to 9.0 on a 0 to 9 scale. The most resistant nine cultigens originated from the U.S., and were primarily adapted cultivars or breeding lines. The most-resistant cultigens, for which multiple-year data were available, were Gy 4, `Clinton', PI 234517, `Poinsett 76', Gy 5, `Addis', M 21, M 27, and `Galaxy'. The most-susceptible cultigens for which multiple year data were available, were PI 288995, PI 176952, PI 178886, and PI 211985. We classified 17 cultigens as highly resistant (1.3 to 3.0), 87 as moderately resistant (3.3 to 5.0), 311 as moderately susceptible (5.3 to 7.0), and 248 as highly susceptible (7.3 to 9.0) for the 663 cultigens with multiple-year data. No plant introduction accessions were found to be more resistant than the most-resistant elite cultivars and breeding lines tested.

scholarly journals Net melon resistance to Didymella bryoniae according to grafting and potassium levels

2012 ◽  
Vol 38 (2) ◽  
pp. 139-143 ◽  
Author(s):  
Edvar de Sousa da Silva ◽  
Felipe Campaner Palangana ◽  
Rumy Goto ◽  
Edson Luiz Furtado ◽  
Dirceu Maximino Fernandes
Keyword(s):  
Chemical Control ◽  
Lesion Size ◽  
Causal Agent ◽  
Didymella Bryoniae ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Stem Lesion ◽  
Insertion Method

Chemical control of the fungus Didymella bryoniae, the causal agent of the disease gummy stem blight in melon, is frequently inefficient; thus, alternatives such as grafting and nutrition must be studied. Rootstocks and potassium levels were tested aimed at controlling this disease in net melon under protected environment. The melon hybrid 'Bônus II', ungrafted and grafted onto 'Dinero' melon and 'Strong Tosa' pumpkin rootstocks, was cultivated and inoculated by using the toothpick insertion method with 7-mm mycelial disks from the isolate D. bryoniae Dbr 37; for control, only toothpick insertion was used. The plants were subjected to the following potassium levels: 0, 62.5, 125, 187.5, 250 mg L-1. Grafted 'Bônus II' melon plants were resistant to the fungus, whereas ungrafted ones were susceptible. The adopted potassium levels did not influence the stem lesion size or the survival of plants.

scholarly journals Greenhouse, Detached-leaf, and Field Testing Methods to Determine Cucumber Resistance to Gummy Stem Blight

1995 ◽  
Vol 120 (4) ◽  
pp. 673-680 ◽  
Author(s):  
Paul C. St. Amand ◽  
Todd C. Wehner
Keyword(s):  
Screening Method ◽  
Leaf Age ◽  
Free Water ◽  
Field Tests ◽  
Infection Process ◽  
Didymella Bryoniae ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Detached Leaf ◽  
Highly Correlated

The effects of leaf age, guttation, stomata and hydathode characteristics, and wounding on the symptom development of gummy stem blight [Didymella bryoniae (Auersw.) Rehm] of cucumber (Cucumis sativus L.) were studied to develop a useful germplasm screening method. Older cucumber leaves were more susceptible than younger leaves in field, greenhouse, and detached-leaf tests. Compared to seedlings with true leaves, seedlings at the cotyledon stage were less susceptible, had a smaller variance for ratings, and were more likely to escape infection. Stomata density and hydathode counts were not correlated with field ratings; but, stomata length on older leaves was highly correlated with susceptibility y. In greenhouse and field tests, susceptibility y increased as guttation increased and actively guttating plants were more susceptible than nonguttating plants. Phylloplane moisture and/or nutrition were more important in the infection process than was stomata] opening. Although important, guttation was not necessary for infection. Dawn inoculation of field or greenhouse tests increased leaf symptoms compared with dusk inoculation. The increase was likely due to the free water and nutrients provided by guttation. Genotype ranks and ratings for detached-leaf tests were not correlated with field results. A useful method, highly correlated (r = 0.82 to 0.96) with field ratings. for screening germplasm in the greenhouse was developed.

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.

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

Plant Disease ◽  
1999 ◽  
Vol 83 (12) ◽  
pp. 1105-1107 ◽  
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.

Molecular Tagging of Gummy Stem Blight Resistance in Watermelon

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 472e-472
Author(s):  
Young-Seok Kwon ◽  
Young Hyun Om ◽  
Leigh Hawkins ◽  
Fenny Dane
Keyword(s):  
Plant Introduction ◽  
Aflp Markers ◽  
Blight Resistance ◽  
Didymella Bryoniae ◽  
Molecular Tagging ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Blight Disease ◽  
Fungus Disease ◽  
Selection Of

The fungus Didymella bryoniae causes gummy stem blight (foliar phase) and black rot (fruit phase) in cucurbits. As resistance to other diseases have been incorporated into cucurbits, losses due to gummy stem blight have increased. Populations derived from crosses between a cultivated watermelon (SS-4), susceptible to the fungus Didymella bryoniae and resistant plant introduction accessions (PI 189225 and PI 272778) are used to detect molecular markers linked to gummy stem blight disease resistance. Genomic DNA was purified from primary leaves of watermelon seedlings before seedlings were inoculated with a spore suspension of the fungus. Disease severity was rated 4 days after inoculation. DNA bulked from resistant or susceptible BC seedlings was amplified to detect AFLP markers. Linkages between gummy stem blight resistance and AFLP markers were identified and should facilitate evaluation and selection of watermelon populations segregating for gummy stem blight resistance.

Factors Promoting Pycnidia Production of Didymella bryoniae, the Causal of Gummy Stem Blight in Cucurbits

2017 ◽  
Vol 45 (1) ◽  
pp. 173-187
Author(s):  
Abdel-Fattah El-Wakil ◽  
Amal Khalil ◽  
Ibrahim El -Abbasi
Keyword(s):  
Didymella Bryoniae ◽  
Stem Blight ◽  
Gummy Stem Blight
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