First Report of Cercospora Leaf Spot Caused by Cercospora cf. alchemillicola in Toona ciliata in Brazil

Silva, Humberson Rocha; Ferreira, M. A.; Souza, Paulo Estevão de; Freitas, Aurivan Soares de; Melo, Maruzanete Pereira de; Costa, S. S.; Pozza, Edson Ampélio

doi:10.1094/pdis-05-15-0572-pdn

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…Silva et al. () reproduced symptoms of the disease in T. ciliata plants only when leaves were wounded before inoculation. In contrast, C. coffeicola penetrated coffee leaves mainly through stomata (Souza et al., ).…”

Section: Discussionmentioning

confidence: 99%

“…Plants were inoculated through wounds on four leaflets per plant. Two wounds per leaflet were made by gently rubbing a circular area 1.8 cm in diameter on the adaxial surface with fine grade steel wool before spraying all leaflets to run off with a conidial suspension of isolate CML3059, prepared as described above and containing 4 × 10 4 conidia/ml (Silva et al, 2016). Controls were sprayed with sterile distilled water.…”

Section: Interaction Between Temperature and Leaf Wetness Duration mentioning

confidence: 99%

“…Silva et al. () reported the occurrence of Cercospora leaf spot ( Cercospora cf. alchemillicola U. Braun and C.F.…”

Section: Introductionmentioning

confidence: 99%

“…alchemillicola did not penetrate T. ciliata through stomata, supporting the hypothesis that some pathogens in this genus need to penetrate the host plant through wounds. Some members of the genus, however, can penetrate the leaf surface directly through natural openings(Paula, Pozza, Santos, Teixeira & Paula, 2015) Silva et al (2016). reproduced symptoms of the disease in T. ciliata plants only when leaves…”

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confidence: 99%

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Cercospora leaf spot in Toona ciliata: Epidemiology and infection process of Cercospora cf. alchemillicola

et al. 2018

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The biology of Cercospora leaf spot (Cercospora cf. alchemillicola) of Toona ciliata was examined in terms of the effects of temperature and duration of foliage wetting on the progress of disease and the mechanism of pathogen infection. To evaluate the effect of temperature on mycelial growth, cercosporin production and conidial germination, experiments were conducted in a 4 × 5 factorial design, with four isolates (HR01, HR02, HR03 and CML3059) at five temperatures (15, 19, 23, 26 and 30°C). The area under the disease progress curve (AUDPC) was calculated in a 3 × 5 factorial design at three temperatures (20, 23 and 29°C) and five leaf wetness durations (0, 12, 24, 48 and 72 hr). Penetration of C. cf. alchemillicola into leaves was examined by scanning electron microscopy. Maximum mycelial growth of all isolates occurred at 24.8°C. HR02 and HR01 produced higher quantities of cercosporin compared with CML3059 and HR03. Temperatures between 21.6 and 23.0°C favoured production of the toxin among isolates. Higher conidial germination rates occurred in isolates HR02 and HR01 compared with other isolates, with optimum germination occurring at 24.2–26.3°C. A leaf wetting period of 72 hr at 23.3°C gave the highest AUDPC value. No hyphal penetration was observed through natural openings. However, germ tubes grew inside wounds on the leaf epidermis. In addition, Phyllachora balansae (cause of tar spot) opened fissures on the leaf epidermis, thus creating wounds enabling C. cf. alchemillicola to infect.

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Section: Discussionmentioning

confidence: 99%

Section: Interaction Between Temperature and Leaf Wetness Duration mentioning

confidence: 99%

“…Silva et al. () reported the occurrence of Cercospora leaf spot ( Cercospora cf. alchemillicola U. Braun and C.F.…”

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Cercospora leaf spot in Toona ciliata: Epidemiology and infection process of Cercospora cf. alchemillicola

et al. 2018

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Cercospora

2022

CABI Compendium

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Characterization of QoI-Fungicide Resistance in Cercospora Isolates Associated with Cercospora Leaf Blight of Soybean from the Southern United States

Shrestha,

Ward,

Allen

et al. 2024

Plant Disease

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Cercospora leaf blight (CLB) of soybean, caused by Cercospora cf. flagellaris, C. kikuchii, and C. cf. sigesbeckiae, is an economically important disease in the southern United States. Cultivar resistance to CLB is inconsistent; therefore, fungicides in the quinone outside inhibitor (QoI) class have been relied on to manage the disease. Approximately 620 isolates from plants exhibiting CLB were collected between 2018 and 2021 from 19 locations in eight southern states. A novel PCR-RFLP assay based on two genes, calmodulin and histone h3, was developed to differentiate between the dominant species of Cercospora, C. cf. flagellaris and C. cf. sigesbeckiae. A multilocus phylogenetic analysis of actin, calmodulin, histone h3, ITS rDNA, and transcription elongation factor 1-α was used to confirm PCR-RFLP results and identify remaining isolates. Approximately 80% of the isolates collected were identified as C. cf. flagellaris, while 15% classified as C. cf. sigesbeckiae, 2% as C. kikuchii, and 3% as previously unreported Cercospora species associated with CLB in the U.S. PCR-RFLP of cytochrome b (cytb) identified QoI-resistance conferred by the G143A substitution. Approximately 64% to 83% of isolates were determined to be QoI-resistant, all containing the G143A substitution. Results of discriminatory dose assays using azoxystrobin (1 ppm) were 100% consistent with PCR-RFLP results. To our knowledge this constitutes the first report of QoI resistance in CLB pathogen populations from Alabama, Arkansas, Kentucky, Mississippi, Missouri, Tennessee, and Texas. In areas where high frequencies of resistance have been identified, QoI fungicides should be avoided, and fungicide products with alternative modes-of-action should be utilized in the absence of CLB-resistant soybean cultivars.

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First Report of Cercospora Leaf Spot Caused by Cercospora cf. alchemillicola in Toona ciliata in Brazil

Cited by 4 publications

References 6 publications

Cercospora leaf spot in Toona ciliata: Epidemiology and infection process of Cercospora cf. alchemillicola

Cercospora leaf spot in Toona ciliata: Epidemiology and infection process of Cercospora cf. alchemillicola

Cercospora

Characterization of QoI-Fungicide Resistance in Cercospora Isolates Associated with Cercospora Leaf Blight of Soybean from the Southern United States

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