|BASSANEZI, R. B.|
|BERGAMIN FILHO, A.|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/14/2006
Publication Date: 7/22/2006
Citation: Bassanezi, R., Bergamin Filho, A., Amorim, L., Gottwald, T.R. 2006. Epidemiology of Huanglongbing in Sao Paulo. Huanglongbing-greening International Workshop, July 14-21, 2006, Ribeiro Preto, Brazil. P.37-38.
Technical Abstract: Huanglongbing (HLB) was reported in 2004 in Sao Paulo, Brazil, and Candidatus Liberibacter asiaticus and Ca. L. americanus were found associated with the disease with prevalence of the second species.The Asian psyllid, Diaphorina citri Kuwayama, reached Brazil 60 years ago, is well established in Sao Paulo orchards, and is the HLB-agent vector in Brazil. However, due to the recent report of HLB in Brazilian groves, few data are available with regard to temporal progress and spatial distribution of the disease in groves of Sao Paulo. Preliminary data, obtained from periodic assessments of symptomatic trees in many citrus blicks from different groves in central region of Sao Paulo, indicate a similar behaviour of the disease in relation to what was observed in countries where Ca. L. asiaticus is present. Aggregation of HLB-symptomatic trees was observed by spatial analysis, however this aggregation was not strong. Secondary foci related to a main cluster of symptomatic trees were often found spread all over the block, indicating that there are dispersal mechanisms of HLB in both short (to nearby trees) and long distances (4 to 22 tree spaces distant) which impede the adoption of an eradication radius of exposed treees, because almost all trees of the block would be eliminated. A greater amount of symptomatic trees was normally found at the edges of the block, mainly where the nearby block has a higher disease indicence. This spatial pattern has been observed such as in block scale as in property scale. For temporal progress of HLB in Sao Paulo, it was observed that the appearance of new HLB-symptomatic trees occurs during all the year with higher intensity during autumn and winter seasons (from April to August). The annual rate of disease progress estimated by logistic model varied from 0.87 to 4.16 in groves 2 to 4 years old where no specific measure to HLB control was applied and were located into farms with high inoculum pressure.