Survival of pathogenic Colletotrichum isolates on dormant buds, twigs and fallen leaves of apple trees in commercial orchards

Hamada, Natasha Akemi; Mio, Louise Larissa May De

doi:10.17660/th2017/72.3.5

Cited by 6 publications

(2 citation statements)

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“…In spite of the results found, it is important to note that this reduction of the inoculum in twigs does not mean that no disease will occur, since Crusius et al (2002) in a study conducted in Santa Catarina State found no difference in the initial incidence of the disease between sprayed and non-sprayed plants, indicating that even minimal amounts of inoculum could lead to Glomerella leaf spot epidemics. In Parana State the survival of Colletotrichum in apple orchard was confirmed in twigs, buds and also on fallen leaves, and the isolates were pathogenic on leaves and apple fruit (Hamada & De Mio, 2017).…”

Section: Resultsmentioning

confidence: 90%

“…Especially for perennial crops such as apple trees, the management of diseases in the tropics can be difficult, since favorable conditions for disease development and the presence of susceptible host tissue occurs over long periods (Ploetz, 2007) As flowers, fruit and leaves are not present, a possible way for the survival of fungi is on woody tissues, as the trunk, branches, or twigs. Most of the pathogens that cause important apple diseases can survive on these parts of the plant, including Colletotrichum spp., the causal agent of Glomerella leaf spot and bitter rot (Jones & Sutton, 1996;Crusius, Forcelini, Sanhueza, & Fernandes, 2002;Sutton, Aldwinckle, Agnello, & Walgenbach, 2014;Hamada & De Mio, 2017); Botryosphaeria dothidea causal agent of Botryosphaeria canker and white rot (Jones & Aldwinckle, 1990); and Neonectria ditissima, which causes European canker and Neonectria fruit rot (Weber, 2014). To reduce inoculum on woody tissues, winter treatments with eradicant products are performed in the vegetative rest period.…”

Section: Introductionmentioning

confidence: 99%

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Survival of pathogens after dormancy in apple tree twigs indicates potential risk as source of inoculum

2022

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Several diseases are difficult to control specially in subtropical regions and perennial hosts where the pathogen survive easily within the plant. The aim of this study was to identify which pathogens are surviving after end of one season and at the beginning of the next season to inform which pathogens represent potential risk as primary inoculum to the next season. Survival of pathogens on apple tree twigs was evaluated during dormancy and on beginning of vegetative growth in four orchards located in the two main apple production regions: Palmas and metropolitan region of Curitiba, in Paraná State, Brazil. For this purpose, 10 cm long asymptomatic twigs were collected from 10 randomly selected plants, 24 twigs per plant. Half of the twigs were left directly (without disinfection) in humid chambers for 30 days at 25ºC. The other half of the twigs were disinfected and kept in a freezer for 12 hours at -16ºC by the Over Night Freezing Incubation Technique (Onfit) and then kept in a humid chamber for 30 days at 25ºC. The fungi Colletotrichum sp., Botryosphaeria sp., Alternaria sp., and Fusarium sp. were detected in the two sampled dates and methodologies in all evaluated regions. Neonectria ditissima was only detected in both orchards from Palmas. The genera found surviving on twigs were confirmed molecularly by BLASTn and were pathogenic in wounded fruits from the cultivar ‘Gala’. Our results indicate that pathogens are surviving in orchards after winter treatment and throughout the apple season, being potential sources of inoculum for infections in flowers and fruits, where the pathogens detected cause important diseases as bitter rot, Neonectria fruit rot, white and black rots, and possibly cause Alternaria and Fusarium rots which have not been extensively studied in Brazil.

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Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Survival of pathogens after dormancy in apple tree twigs indicates potential risk as source of inoculum

2022

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Comparative epidemiology of three Colletotrichum species complex causing Glomerella leaf spot on apple

Moreira

Filho²,

Zeviani

et al. 2020

Eur J Plant Pathol

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Identification and Fungicide Sensitivity of Colletotrichum spp. from Apple Flowers and Fruitlets in Brazil

et al. 2023

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Glomerella leaf spot (GLS) and bitter rot (BR), caused by Colletotrichum spp., are major diseases on apple in southern Brazil. Among IPM tools for disease management in commercial orchards, fungicides remain an important component. This study aimed to identify Colletotrichum species from cultivar Eva in Paraná state orchards, evaluate their in vitro sensitivity to cyprodinil, tebuconazole, iprodione, and fluazinam, and determine the baseline in vitro sensitivity of these isolates to benzovindiflupyr and natamycin. Most isolates belonged to C. melonis and C. nymphaeae of the C. acutatum species complex. The two species varied in sensitivity to fluazinam and tebuconazole, but no variability was found for any other fungicide. The lowest EC50 values of Colletotrichum spp. were observed for cyprodinil (mean EC50 < 0.02) and benzovindiflupyr (mean EC50 < 0.05); EC50 values were intermediate for fluazinam (mean EC50 < 0.33) and tebuconazole (mean EC50 < 0.14); and highest for natamycin (mean EC50 < 5.56) and iprodione (mean EC50 > 12). Cyprodinil and fluazinam are registered for use in Brazil for apple disease management but not specifically for GLS and BR. Tebuconazole is one of the few products registered for Colletotrichum spp. control in apples. As conclusion, flowers and fruitlets can serve as sources of inoculum for GLS and BR disease; C. acutatum was the predominant species complex in these tissues; cyprodinil and fluazinam applications may suppress GLS and BR; and benzovindiflupyr and natamycin warrant further investigation for GLS and BR disease control of apple due to comparably high in vitro sensitivity.

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Survival of pathogenic Colletotrichum isolates on dormant buds, twigs and fallen leaves of apple trees in commercial orchards

Cited by 6 publications

References 20 publications

Survival of pathogens after dormancy in apple tree twigs indicates potential risk as source of inoculum

Survival of pathogens after dormancy in apple tree twigs indicates potential risk as source of inoculum

Comparative epidemiology of three Colletotrichum species complex causing Glomerella leaf spot on apple

Identification and Fungicide Sensitivity of Colletotrichum spp. from Apple Flowers and Fruitlets in Brazil

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