Dinâmica temporal da Clorose Variegada dos Citros em três regiões do Estado de São Paulo

Laranjeira, F. F.; Filho, Armando Bergamin; Amorim, Lílian; Berger, R. D.; Gottwald, T. R.

doi:10.1590/s0100-41582003000500003

Cited by 7 publications

(5 citation statements)

References 6 publications

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“…This might occur because asymptomatic infected trees may already serve as an inoculum source inside the orchard. We also observed a trend of CVC diseased trees concentrated at the edge of the experimental area, as previously reported, 40 probably due to the arrival of infectious insect vectors from diseased neighboring citrus blocks, similar to HLB. 41 The long incubation period and high number of diseased trees at the edges, indicative of an influx of bacterialiferous sharpshooters from diseased citrus trees in neighboring blocks, was probably more important as a continuous source of primary inoculum in plots under vector control programs.…”

Section: Discussionsupporting

confidence: 87%

Inoculum reduction and vector control on the temporal progress of citrus variegated chlorosis incidence

Bassanezi

Primiano

Moreira

2021

Pest Management Science

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BACKGROUND: Citrus variegated chlorosis (CVC) is an important citrus disease caused by the sharpshooter-transmitted bacterium Xylella fastidiosa subsp. pauca. Information about the efficacy of its disease management is bounded to either inoculum reduction or vector control. This study aimed to assess the role of different frequencies of roguing of symptomatic trees combined with different chemical control programs for the sharpshooters on CVC temporal progress. The experimental area was set up in October 2005 and had a 3 × 3 factorial design. Symptomatic tree removal intervals were every 28, 56, and 112 days to May 2012. Vector control treatments were no control, program A (PA), and program B (PB). Contact insecticides were sprayed every 28 (PA) or 14 (PB) days. Trees within both programs were treated with systemic and foliar insecticides to October 2008. After this, systemic insecticides were discontinued and only foliar treatments were applied. The number of diseased trees and the sharpshooter population were assessed to April 2015. RESULTS: Detection of the first symptomatic trees was similar for all treatments and occurred, on average, in month 50 after planting. Sharpshooter population and cumulative disease incidence were similar for all roguing intervals and between vector control programs, differing in plots with no control. We observed a reduction over 85% in disease incidence for both PA and PB compared with no control.CONCLUSION: These results support systematic control of sharpshooters as an efficient strategy for reducing CVC progress.

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Section: Discussionsupporting

confidence: 87%

Inoculum reduction and vector control on the temporal progress of citrus variegated chlorosis incidence

Bassanezi

Primiano

Moreira

2021

Pest Management Science

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“…Incidence was determined for each disease assessment date as proportion of symptomatic plants. Three growth curve models – logistic, monomolecular, Gompertz – were fitted to disease progress curves by nonlinear regression using the software Statistica 5.0 and the Quasi‐Newton method (Campbell & Madden, 1990; Laranjeira et al , 2003).…”

Section: Methodsmentioning

confidence: 99%

Progress, spread and natural transmission of Bahia bark scaling of citrus in Brazil

Laranjeira

Barbosa

Santos-Filho

et al. 2006

Annals of Applied Biology

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Progress, spread and natural transmission of Bahia bark scaling of citrus were evaluated in a trial where 240 screenhouse-nursed nucellar grapefruit plants -'Clason', 'Little River Seedless', 'Red Blush', 'Reed' and 'Howell Seedless' cvswere planted alongside and 5 m apart from a 10-year-old symptomatic 'Marsh Seedless' grapefruit orchard. Plants were distributed in 16 rows of 15 trees, with three plants of each cultivar per row. Eight trial plants were kept in screen cages. Incidence of symptomatic plants was assessed at 3-months intervals, for 5 years, and for further 2 years at irregular intervals. Cumulative maps of disease incidence were produced for each assessment date and used in all analyses. Temporal progress was analysed by nonlinear fitting of three disease progress models. Spread was characterised in three levels of spatial hierarchy by the following analyses: ordinary runs, binomial dispersion index, binary power law fitting, isopath mapping and nonlinear fitting of disease gradient models. The first symptomatic plant was detected 2 years after planting. In the last disease assessment, 5 years after the first, 98% of the unprotected plants were symptomatic. None of the screen-caged trees showed any symptoms. Bahia bark scaling progress was polyetic and best described by the logistic model. Ordinary runs analysis showed little if any evidence of transmission between adjacent trees. Diseased plants showed a very aggregated pattern inside quadrats (D > 5 and b > 1.53). Isopath mapping showed that main spread was only because of the primary inoculum source. Secondary foci were also observed, but they were never dissociated from main initial disease focus. Disease gradient followed wind direction, starting near the original inoculum source and was best described by exponential model. These results support a hypothesis of Bahia bark scaling transmission by air-borne vectors with limited dispersion ability.

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“…Under natural conditions, most X. fastidiosa hosts are asymptomatic but can act as reservoirs that contribute to X. fastidiosa establishment, maintenance, and spread. The importance of asymptomatic reservoirs on disease epidemiology varies among pathosystems; for example, they appear important for PD in Northern California (2, 115) but not for CVC in Brazil (83). In addition, different pathogen multiplication rates have been observed in noncrop plants, suggesting that different hosts may contribute differentially to spread (e.g., 119).…”

Section: Role Of Nonsymptomatic Pathogen Reservoirsmentioning

confidence: 99%

Xylella fastidiosa: Insights into an Emerging Plant Pathogen

Sicard

Zeilinger

Vanhove

et al. 2018

Annu. Rev. Phytopathol.

181

157

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The bacterium Xylella fastidiosa re-emerged as a plant pathogen of global importance in 2013 when it was first associated with an olive tree disease epidemic in Italy. The current threat to Europe and the Mediterranean basin, as well as other world regions, has increased as multiple X. fastidiosa genotypes have now been detected in Italy, France, and Spain. Although X. fastidiosa has been studied in the Americas for more than a century, there are no therapeutic solutions to suppress disease development in infected plants. Furthermore, because X. fastidiosa is an obligatory plant and insect vector colonizer, the epidemiology and dynamics of each pathosystem are distinct. They depend on the ecological interplay of plant, pathogen, and vector and on how interactions are affected by biotic and abiotic factors, including anthropogenic activities and policy decisions. Our goal with this review is to stimulate discussion and novel research by contextualizing available knowledge on X. fastidiosa and how it may be applicable to emerging diseases.

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Dinâmica temporal da Clorose Variegada dos Citros em três regiões do Estado de São Paulo

Cited by 7 publications

References 6 publications

Inoculum reduction and vector control on the temporal progress of citrus variegated chlorosis incidence

Inoculum reduction and vector control on the temporal progress of citrus variegated chlorosis incidence

Progress, spread and natural transmission of Bahia bark scaling of citrus in Brazil

Xylella fastidiosa: Insights into an Emerging Plant Pathogen

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