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Gasparoto M.C.G.,University of Sao Paulo | Coletta-Filho H.D.,Anhanguera | Bassanezi R.B.,Fundo de Defesa da Citricultura FUNDECITRUS | Lopes S.A.,Fundo de Defesa da Citricultura FUNDECITRUS | And 2 more authors.
Plant Pathology | Year: 2012

The objectives of this work were (i) to determine the influence of temperature on infection of citrus by 'Candidatus Liberibacter asiaticus' and 'Candidatus Liberibacter americanus', the two bacterial species associated with citrus huanglongbing (HLB) in Brazil, and (ii) to determine the influence of temperature on citrus colonization by 'Ca. L. asiaticus', which has taken over from 'Ca. L. americanus' as the predominant species in Brazil since 2008. Two experiments were carried out with graft-inoculated Valencia oranges on Rangpur lime rootstocks. Immediately after inoculation the plants were maintained for 423days in growth chambers under the following night/day temperature conditions: 17/22, 22/27 or 27/32°C, with a dark/light photoperiod of 8/16h. Infection and colonization of plants were determined using quantitative PCR (qPCR). 'Candidatus Liberibacter americanus' did not infect the plants maintained at 27/32°C; however, infection by 'Ca. L. asiaticus' occurred at all studied temperatures. Two months after inoculation, 'Ca. L. asiaticus' was distributed throughout the inoculated plants, with mean C t values in the range of 30-31 for leaves and 25-28 for roots. Over time, 'Ca. L. asiaticus' reached the highest titres in mature leaves (mean C t value=26·7) of citrus plants maintained at 22/27°C. 'Candidatus Liberibacter asiaticus' colonization of citrus plants was negatively affected by the daily temperature regime of 27/32°C (mean C t value in mature leaves=33·6). © 2012 The Authors. Plant Pathology © 2012 BSPP.


Behlau F.,Fundo de Defesa da Citricultura Fundecitrus | Barelli N.L.,Fundo de Defesa da Citricultura Fundecitrus | Belasque J.,University of Sao Paulo
Journal of Plant Pathology | Year: 2014

Asiatic citrus canker (ACC), caused by the bacterium Xanthomonas citri subsp. citri, is one of the most serious diseases affecting citrus worldwide. In areas under quarantine/ eradication, such as Sao Paulo state (SPS), Brazil, the impact of ACC is related to the production costs for inspections and tree removal. Several protocols for eradication were adopted in SPS since the first detection of ACC in 1957. Among these, the one carried out from 1999 to 2009 was the most effective for maintaining the disease at a very low level throughout the state. That protocol mandated periodic inspections and removal of symptomatic and asymptomatic trees based on disease incidence in the block. After 2009 the eradication protocols were less stringent and ACC incidence continued to increase. This study aimed at identifying the key factors for the successful eradication of ACC in a farm located in SPS. Data on the outbreaks from 2006 to 2010 and the related control measures adopted were analysed. The farm remained under quarantine from July 2006 to March 2010. Twelve disease foci were detected from July 2006 to January 2008 and incidence of symptomatic tress ranged from 0.05% to 0.43%. The successful eradication of ACC in this farm is attributed to the relatively low number of diseased trees in all foci detected in the course of frequent and well-executed inspections. The results of this case study may be used to guide containment protocols in other citrus production areas of Brazil or countries where ACC is either absent or has a low incidence. © 2014, Edizioni ETS. All rights reserved


Silva-Junior G.J.,University of Sao Paulo | Sposito M.B.,University of Sao Paulo | Marin D.R.,Fundo de Defesa da Citricultura Fundecitrus | Amorim L.,University of Sao Paulo
Crop Protection | Year: 2014

Citrus postbloom fruit drop (PFD) caused by Colletotrichum spp. occurs in several countries in the Americas reducing yields by as much as 80%. Fungicide application is the main strategy for PFD control. Two field trials were performed to assess the timing of applications and another two were set up to investigate the efficacy of fungicides for PFD control in São Paulo State, Brazil. The percentage of symptomatic flowers per branch, the number of persistent calyces per branch, the number of fruit per branch and yield were evaluated. Four sprays of trifloxystrobin+tebuconazole, carbendazim, difenoconazole or cyprodinil+fludioxonil were effective in reducing yield losses due to PFD, however the trifloxystrobin+tebuconazole mixture was significantly more effective than all other treatments. The conventional PFD control programme, with one spray of difenoconazole followed by up to three carbendazim applications at different intervals, showed variable results, probably due to rainfall. The trifloxystrobin+tebuconazole mixture was effective at controlling PFD under favourable conditions for infection and can be recommended in PFD control programmes. © 2014.


Belasque Jr. J.,Fundo de Defesa da Citricultura Fundecitrus | Barbosa J.C.,São Paulo State University | Filho A.B.,University of Sao Paulo | Massari C.A.,Fundo de Defesa da Citricultura Fundecitrus
Tropical Plant Pathology | Year: 2010

Recently the São Paulo state government mitigated its citrus canker eradication methodology adopted since 1999. In April 2009 at least 99.8% of commercial sweet orange orchards were free of citrus canker in São Paulo state. Consequently the mitigation of the eradication methodology reduced the high level of safety and the competitiveness of the citrus production sector in São Paulo state, Brazil. Therefore we suggest the re-adoption of the same eradication methodology of citrus canker adopted in São Paulo from 1999 to 2009, or the adoption of a new methodology, effective for citrus canker suppression, because in new sample surveys citrus canker was detected in >0.36% of affected orchards. This incidence threshold was calculated by using the Duncan test (P=0.05) to compare the yearly sample surveys conducted in São Paulo state to estimate citrus canker incidence between 1999 and 2009. The calculated minimum significant level was 0.28% among sample surveys and the lowest citrus canker incidence in São Paulo state was 0.08%, occurring in 2001. Thus, as an alternative, we suggest the adoption of a new eradication methodology for citrus canker suppression when a new sample survey detected >0.36% of affected orchards in São Paulo state, Brazil.


Leal R.M.,UNICASTELO | Barbosa J.C.,São Paulo State University | Costa M.G.,UNICASTELO | Belasque Junior J.,Fundo de Defesa da Citricultura FUNDECITRUS | And 2 more authors.
Revista Brasileira de Fruticultura | Year: 2010

The aim of this study was to use geostatistics to verify the spatial distribution of Huanglongbing (greening) in oranges orchards on agricultural property located in the city of Araraquara, São Paulo. To determine the number of plants with greening, periodic inspections every three months were made from March 2005 until July 2007, counting the number of plants in each stand with the characteristic symptoms of the disease. A descriptive analysis of the data was undertaken, and geostatistics were used to verify the spatial distribution of greening through the adjustment of semivariograms and interpolation of data by kriging. The spatial dependence of plants with greening formed a beam of aggregation of 300 to 560 m, indicated an aggregated distribution of the disease. Diagrams of kriging showed that initial focus of plants with greening started at the border in the farm and there was an expansion of the disease through the entire area. The interval of inspections every three months was not appropriate to reduce the greening in the farm.


Fonseca A.E.,Fundo de Defesa da Citricultura Fundecitrus | Arf O.,São Paulo State University | Junior V.O.,São Paulo State University | Buzetti S.,São Paulo State University | Rodrigues R.A.F.,São Paulo State University
Pesquisa Agropecuaria Tropical | Year: 2012

The influences of soil management and nitrogen fertilization are not well defined for upland rice. Thus, this research was carried out to evaluate the yield components, milled grain yield, and grain yield of upland rice cultivars under sprinkler irrigation, according to soil management and topdressing nitrogen doses. The experiment was conducted in Selvíria, Mato Grosso do Sul State, Brazil, under field conditions, for two consecutive harvest times: 2003/2004 (BRS Talento cultivar) and 2004/2005 (IAC 202 cultivar). The randomized blocks design was adopted, consisting of the combination of three soil management systems (disc harrow + leveling disc harrow, scarifier + leveling disc harrow, and no-till) and six topdressing nitrogen doses (0 kg ha-1, 25 kg ha-1, 50 kg ha-1, 75 kg ha-1, 100 kg ha-1, and 125 kg ha-1), with four replications. The leaf N concentration, plant height, yield components, milled grain yield, and grain yield were evaluated. The scarifier + leveling disc harrow system provided the highest grain yield for both cultivars, while the topdressing nitrogen fertilization just affected the IAC 202 cultivar yield, without affecting the milled grains yield.


de Araujo D.,São Paulo State University | Raetano C.G.,São Paulo State University | Ramos H.H.,Instituto Agronomico CEA IAC | Sposito M.B.,Fundo de Defesa da Citricultura FUNDECITRUS | Prado E.P.,São Paulo State University
Summa Phytopathologica | Year: 2013

The chemical control of the causal agent of citrus black spot (CBS) has been highlighted for the excessive required number of sprayings, considerably increasing citrus production costs. Improvements in the spray efficiency and reductions in the quantity of phytosanitary products have already been searched, but the results of that practice are not consistent yet for its use at commercial scale. Thus, the aim of the present study was to evaluate the interference of reduced spray volumes in black spot control in citrus fruits. The experiment was carried out in commercial citrus orchard with 16-year-old plants of 'Valencia' variety, during 2007 agricultural season. Treatments consisted of three spray volumes: 3.5; 4.5 and 8.5 liters.plant-1, applied with Arbus 2000/Export airblast sprayer with special manifold of hydraulic nozzles, using fungicides and periods recommended for the disease control, totaling four sprayings plus a control treatment (without spray). The disease incidence and severity were evaluated by visual diagrammatic scale of notes in two different periods (preharvest and harvest), at three plant heights (low, middle and top) and three horizontal sections (entrance, frontal and exit) in two sides of the plant. The fallen fruits were counted every fifteen days, for previously selected plants, from the beginning of maturation to harvest, and the production was quantified (kg.plant-1). The disease incidence and severity were significantly lower when sprayings were done with 8.5 liters.plant-1 in the first evaluation period (pre-harvest), but in the harvest period there were not differences between the same parameters when 4.5 or 8.5 liters.plant-1 were sprayed. None of those treatments reduced the disease on the top section of plants, compared to control. The plant sections with fruits more exposed to sun rays, top and right side of the plant, demonstrated higher disease incidence and severity. The volume reduction from 8.5 to 4.5 liters.plant-1 can be adopted for citrus orchards without damaging the CBS control level.


Patent
Fundo De Defesa Da Citricultura Fundecitrus and Instituto Valenciano Of Investigaciones Agrarias | Date: 2015-06-08

The invention provides a method for controlling Huanglongbing (HLB) disease of citrus plants through expressing genes encoding synthases for sesquiterpenes such as -caryophyllene, and -copaene, and combinations thereof, in citrus plants. Methods of controlling HLB comprising applying at least one purified sesquiterpene, which repels Diaphorina citri and/or Tryoza erytrae psyllid insects, so as to control the HLB disease of citrus plants, are also disclosed.


Patent
Fundo De Defesa Da Citricultura Fundecitrus and Instituto Valenciano Of Investigaciones Agrarias | Date: 2015-06-08

The invention provides a method for controlling Huanglongbing (HLB) disease of citrus plants through expressing genes encoding synthases for sesquiterpenes such as -caryophyllene, and -copaene, and combinations thereof, in citrus plants. Methods of controlling HLB comprising applying at least one purified sesquiterpene, which repels Diaphorina citri and/or Tryoza erytrae psyllid insects, so as to control the HLB disease of citrus plants, are also disclosed.


Patent
Instituto Valenciano Of Ivestigaciones Agrarias and Fundo De Defesa Da Citricultura Fundecitrus | Date: 2010-10-26

The invention provides a method for controlling Huanglongbing (HLB) disease of citrus plants through expressing genes encoding synthases for sesquiterpenes such as -caryophyllene, and -copaene, and combinations thereof, in citrus plants. Methods of controlling HLB comprising applying at least one purified sesquiterpene, which repels Diaphorina citri and/or Tryoza erytrae psyllid insects, so as to control the HLB disease of citrus plants, are also disclosed.

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