A new method for inoculation of fruit with Guignardia citricarpa, the causal agent of citrus black spot

Baldassari, Ricardo Braga; Reis, R. F.; Goes, António de

doi:10.1007/s10658-008-9331-0

Cited by 16 publications

(17 citation statements)

References 6 publications

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“…The method of Baldassari et al (2009) used in our pathogenicity test was successful and inoculated fruit showed typical virulent spot symptoms of CBS. However, there were only a few fruit with hard spot symptoms as reported by Baldassari et al (2009) in Brazil. The first symptoms of CBS resulting from the inoculations of Valencia Late fruit occurred at 73 days and other characteristic symptoms were observed after 225 days.…”

Section: Discussionmentioning

confidence: 90%

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Crop loss, aetiology, and epidemiology of citrus black spot in Ghana

et al. 2012

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Citrus Black Spot (CBS), caused by Guignardia citricarpa, was detected for the first time in Ghana and in West Africa. The disease was first observed in the Eastern Region in 1999 with typical disease symptoms including hard spot, virulent spot and false melanose were observed on several citrus species. A survey revealed that the disease has reached epidemic levels in the citrus-producing areas of the Eastern and Ashanti regions and is spreading rapidly within these areas and to other regions of the country. Currently, CBS is the most important fruit disease of citrus in Ghana, causing about 22% crop loss. Although the disease does not cause postharvest decay and the internal quality of the fruit is not affected, significant amounts of blemished fruit are discarded at the markets. Disease incidence and severity was found to be higher on mature than on young citrus trees. Pycnidia were found on fruit with hard spot symptoms, and pycnidia and pseudothecia typical of Guignardia spp. were found on decomposing leaves. Two species, G. citricarpa and G. mangiferae, were isolated from 15% of the samples collected and identified using the Oatmeal Agar test and by PCR with species-specific DNA primers. Isolates of G. citricarpa produced CBS symptoms after 80 to 233 days on 75% of the artificially inoculated young fruit of Valencia Late sweet orange. The fungus was reisolated from symptomatic, inoculated fruit completing Koch's postulates. Isolates of the endophyte G. mangiferae did not induce symptoms in the pathogenicity tests. In epidemiological studies, infections were detected from November to February for the minor cropping season and from May to November for the major season. Fruit of Valencia Late sweet orange Eur J Plant Pathol (2012) 133:657-670

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Section: Discussionmentioning

confidence: 90%

“…The method described by Baldassari et al (2009) was used to produce inoculum and test pathogenicity. Autoclaved leaf discs of Valencia Late sweet orange (12-mm diameter) were placed onto 2% WA in contact with 5-mm-diameter agar plugs obtained from the periphery of actively growing cultures of Guignardia spp.…”

Section: Pathogenicity Testsmentioning

confidence: 99%

Crop loss, aetiology, and epidemiology of citrus black spot in Ghana

et al. 2012

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“…The efficacy of culling fruit in the field and/or in the packing house is limited owing to the presence of latent infections in asymptomatic fruit that may develop symptoms after harvest during transport and storage (Kotzé, 1981;Agostini et al, 2006;Baldassari et al, 2007). In addition, symptoms on fruit are variable and unspecific, with the exception of hard spot with pycnidia.…”

Section: Entry Pathway I: Citrus Fruit Commercial Tradementioning

confidence: 99%

Scientific Opinion on the risk of Phyllosticta citricarpa (Guignardia citricarpa) for the EU territory with identification and evaluation of risk reduction options

2014

EFS2

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The Panel conducted a risk assessment of Phyllosticta citricarpa for the EU. P. citricarpa causes citrus black spot (CBS) and is absent from the EU. Under the scenario of absence of specific risk reduction options against P. citricarpa, the risk of entry of P. citricarpa was rated as likely for citrus plants for planting and citrus fruit with leaves, moderately likely for citrus fruit without leaves, unlikely for citrus leaves for cooking and very unlikely for Tahiti lime fruit without leaves. Establishment was rated as moderately likely because susceptible hosts are widely available and environmental conditions in many EU citrus-growing areas are suitable (with high uncertainty) for P. citricarpa ascospore production, dispersal and infection. Current fungicide treatments will not prevent establishment. Environmental favourability is increased by the use of sprinkler and micro-sprinkler irrigation in some EU citrus-growing locations. Spread with trade was rated as moderately likely. Model results indicate that CBS epidemics are most likely to develop in EU citrus-growing areas in late summer to early autumn and in some locations also in late spring to early summer. CBS is expected to affect mainly lemons and late-maturing sweet orange and mandarin varieties, with moderate negative consequences for the production of fresh fruit, but with environmental impact of additional fungicide treatments. Negative consequences would be minor for early-maturing citrus varieties and minimal for citrus for processing. Uncertainty concerning the consequences is high, mainly because of the lack of data on critical climate response parameters for the pathogen but also because information on impact in areas at the limits of the current distribution is scarce. Since eradication and containment are difficult, phytosanitary measures should focus on preventing entry. Current phytosanitary measures are evaluated to be effective, with the exception of pest-free production sites. SUMMARYThe European Commission requested EFSA to prepare a pest risk assessment of the citrus black spot (CBS) fungus Guignardia citricarpa Kiely (all strains pathogenic to Citrus), to identify risk reduction options and to evaluate their effectiveness in reducing the risk to plant health posed by this organism in the EU territory. 4 EFSA was also requested to carry out an evaluation of the effectiveness of the present EU requirements 5 for Guignardia citricarpa in reducing the risk of introduction of this harmful organism into the EU. Furthermore, EFSA was requested to assess the risk associated with Citrus latifolia plants, including fruit, for the entry of this organism into the EU.Following a request from the European Commission, the EFSA's Scientific Panel on Plant Health (PLH) had undertaken in the summer 2013 a public consultation on the draft Scientific Opinion on the risk to plant health of Phyllosticta citricarpa (Guignardia citricarpa) for the EU territory. The comments received during the public consultation were taken into account and the Scientific O...

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“…The presence of hyphae close to the stomata reinforces this hypothesis. With artificial inoculation, false melanosis appears only when a high concentration of inoculum (10 8 conidia/ml) is applied to the fruit attached to the trees and the incubation period is around 150 days (Almeida 2009;Baldassari et al 2009). When the plant is exposed to a high inoculum concentration, it reacts faster to infection than when a low amount of inoculum is used, accumulating phenolic compounds.…”

Section: Discussionmentioning

confidence: 99%

“…It was not clear in that report how the authors guarantee that the symptoms originated from the artificial inoculation, because no control was described. Even the latest reported method of artificial inoculation of oranges does not allow a precise study for symptom development, because only false melanosis was consistently reproduced 150 days after inoculation on Pera sweet orange cultivar (Baldassari et al 2009). No hard spot symptoms developed on inoculated fruit of Pera cv.…”

Section: Introductionmentioning

confidence: 99%

Histopathology of black spot symptoms in sweet oranges

et al. 2011

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In Brazil, citrus black spot (CBS) caused by Guignardia citricarpa is a major disease that has different symptoms on fruit. In this study, fruit of Citrus sinensis infected by G. citricarpa and showing the symptoms false melanosis, freckle spot and hard spot were cross-sectioned and analysed anatomically and histochemically by light microscopy. Immunohistological assays were performed. All symptoms were accompanied by a thickening of the cuticle. False melanosis lesions did not contain pycnidia and remained restricted to the epicarp or to the first layers of the mesocarp. The stomata in this type of lesion showed phenolic compounds in the guard cells and in the sub-stomatal chamber. In some samples, the guard cells and their surrounding cells lysed, and a wound meristem began to form underneath them. Freckle spot and hard spot lesions had very similar histological alterations to the epicarp and mesocarp, but in our samples only hard spot lesions contained pycnidia. Both of these symptoms were accompanied by protein inclusions. Epidermal and sub-epidermal cells located in the oil-gland region were obliterated, causing alterations in these structures. All symptoms had regions that stained strongly for lipids and phenols.

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A new method for inoculation of fruit with Guignardia citricarpa, the causal agent of citrus black spot

Cited by 16 publications

References 6 publications

Crop loss, aetiology, and epidemiology of citrus black spot in Ghana

Crop loss, aetiology, and epidemiology of citrus black spot in Ghana

Scientific Opinion on the risk of Phyllosticta citricarpa (Guignardia citricarpa) for the EU territory with identification and evaluation of risk reduction options

Histopathology of black spot symptoms in sweet oranges

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