Epidemiological aspects of Didymella bryoniae, the cause of stem and fruit rot of cucumber

Steekelenburg, N.A.M. van

doi:10.1007/bf01976346

Cited by 39 publications

(26 citation statements)

References 7 publications

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“…Sacc), is the most destructive disease of watermelon in greenhouses (1,26) and in the major watermelon-producing areas of the southeastern United States (22,24). The disease can spread rapidly and cause significant yield reductions in warm, wet conditions (1,20).…”

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confidence: 99%

Relationship Between Fungicide Sensitivity and Control of Gummy Stem Blight of Watermelon Under Field Conditions

et al. 2012

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Thomas, A., Langston, D. B., Jr., Sanders, H. F., and Stevenson, K. L. 2012. Relationship between fungicide sensitivity and control of gummy stem blight of watermelon under field conditions. Plant Dis. 96:1780-1784.Gummy stem blight (GSB), caused by the fungus Didymella bryoniae, is the most destructive disease of watermelon and is managed primarily with fungicides. D. bryoniae has developed resistance to many fungicides that were once very effective, including azoxystrobin, boscalid, and thiophanate-methyl. Field experiments were conducted in Tifton (TN) and Reidsville (RV), GA in 2009 and 2010 to establish a relationship between frequency of resistance to a fungicide based on in vitro assays and its efficacy in the management of GSB. Frequency of resistance to boscalid, thiophanate-methyl, and azoxystrobin was >0.80 in isolates collected from nontreated plots in both locations and years. All isolates collected after six applications of boscalid, thiophanatemethyl, or azoxystrobin were resistant to the respective fungicide. All isolates collected from treated and nontreated plots were sensitive to tebuconazole and difenoconazole. GSB severity was assessed on a weekly basis from 63 days after planting. GSB severity in plots treated with boscalid, thiophanate-methyl, or azoxystrobin was not significantly different from that in the nontreated plots (39%, TN-2009; 45%, TN-2010; and 16%, RV-2010). GSB severity in tebuconazole-treated plots (27%, TN-2009; 14%, TN-2010; and 4%, RV-2010) was significantly lower than all other treatments and the nontreated control. There was a consistent negative association between frequency of fungicide resistance and disease control in the field. Thus, knowledge of the frequency of fungicide resistance in the pathogen population will be helpful in selecting the most effective fungicides for the management of GSB in watermelon fields.

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confidence: 99%

Relationship Between Fungicide Sensitivity and Control of Gummy Stem Blight of Watermelon Under Field Conditions

et al. 2012

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“…Sacc), is the most destructive disease of watermelon in greenhouses (1,43) and in the major watermelon-producing areas of the southeastern United States (37,40). The disease can develop rapidly and cause significant yield reductions under warm and wet conditions (1).…”

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confidence: 99%

Baseline Sensitivity and Cross-Resistance to Succinate-Dehydrogenase-Inhibiting and Demethylation-Inhibiting Fungicides in Didymella bryoniae

2012

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Thomas, A., Langston, D. B., Jr., and Stevenson, K. L. 2012. Baseline sensitivity and cross-resistance to succinate-dehydrogenase-inhibiting and demethylation-inhibiting fungicides in Didymella bryoniae. Plant Dis. 96:979-984.Didymella bryoniae, which causes gummy stem blight (GSB) of watermelon, has a history of developing resistance to fungicides, most recently the succinate-dehydrogenase-inhibiting (SDHI) fungicide boscalid. To facilitate fungicide resistance monitoring, baseline sensitivity distributions were established for demethylation-inhibiting (DMI) fungicides tebuconazole and difenoconazole and the SDHI fungicide penthiopyrad, and reestablished for the SDHI fungicide boscalid. In all, 71 isolates with no known prior exposure to SDHIs or DMIs were used to determine the effective concentration at which mycelial growth was inhibited by 50% (EC50). EC50 values for boscalid, penthiopyrad, tebuconazole, and difenoconazole were 0.018 to 0.064, 0.015 to 0.057, 0.062 to 0.385, and 0.018 to 0.048 ng/ml, with median values of 0.032, 0.026, 0.118, and 0.031 fig/ml, respectively. Significant positive correlations between the sensitivity to penthiopyrad and boscalid {P < 0.0001, r = 0.75) and between tebuconazole and difenoconazole {P < 0.0001, r = 0.59) indicate a potential for cross-resistance between chemically related fungicides. In 2009, 103 isolates from fungicidetreated watermelon fields were tested for sensitivity to boscalid and penthiopyrad using a discriminatory concentration of 3.0 ng/ml. Of the isolates tested, 82 were insensitive and 14 were sensitive to both fungicides. Because of the significant potential for cross-resistance between closely related fungicides, growers will be advised not to use both SDHIs or both DMIs successively in the same fungicide spray program.

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“…Van Steekelenburg (1983) found that ascospore release was dependent of humid conditions for a certain period.…”

Section: Discussionmentioning

confidence: 98%

Studies of Didymella bryoniae: The influence of nutrition and cultural practices on the occurrence of stem lesions and internal and external fruit rot on different cultivars of cucumber

Neergaard¹,

Haupt²,

Rasmussen³

1993

Netherlands Journal of Plant Pathology

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Cucumber plants of different cultivars grown under various levels of nutrient supply, climatic conditions and different pruning practices were inoculated with Didymella bryoniae (Auersw.) Rehm. Increased concentration of the nutrient solution in the rockwool slabs leading to a higher amount of dry matter content in the plant tissue resulted in a lower percentage of internal and external fruit rot in the cultivars Daleva and LD 290/82 (D~ehnfeldt), and in lower percentage of internal fruit rot in cv. Aminex, whereas the effect on cv. Dalibor was insignificant. Differences between cultivars were observed, cv. Dalibor showing the highest level of resistance against internal fruit rot and lowest incidence of nodal and internodal lesions.Separate factors appear to affect the establishment of the pathogen in the nodal tissue and its invasion of the internodal tissue. By raising the temperature to daytime level 3 h before sunrise, the risk of extended periods with high humidity was limited and the incidence of internal fruit rot was reduced. An increased incidence of nodal and internodal lesions and external fruit rot was observed at reduced pruning, leaving wilted leaves and shoots on the plants.

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Epidemiological aspects of Didymella bryoniae, the cause of stem and fruit rot of cucumber

Cited by 39 publications

References 7 publications

Relationship Between Fungicide Sensitivity and Control of Gummy Stem Blight of Watermelon Under Field Conditions

Relationship Between Fungicide Sensitivity and Control of Gummy Stem Blight of Watermelon Under Field Conditions

Baseline Sensitivity and Cross-Resistance to Succinate-Dehydrogenase-Inhibiting and Demethylation-Inhibiting Fungicides in Didymella bryoniae

Studies of Didymella bryoniae: The influence of nutrition and cultural practices on the occurrence of stem lesions and internal and external fruit rot on different cultivars of cucumber

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