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United States Department of Agriculture

Agricultural Research Service

Title: Distance of Spread of Asian Citrus Canker from Source of Infection in Commercial Plantings in Sao Paulo, Brazil

item Amorim, L. - UNIV. OF SAO PAULO, BR
item Jesus Junior, W. C. - FUNDECITRUS, BRAZIL
item Bassanezi, R. B. - FUNDECITRUS, BRAZIL
item Bergamin-Filho, A. - UNIV. OF SAO PAULO, BR
item Gottwald, Timothy

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: September 30, 2005
Publication Date: November 7, 2005
Citation: Amorim, L., Jesus Junior, W., Bassanezi, R., Bergamin-Filho, A., Gottwald, T.R. 2005. Distance of spread of asian citrus canker from source of infection in commercial plantings in Sao Paulo, Brazil. International Citrus Canker and Huanglongbing Workshop, Orlando, FL, November 7-11, 2005. C8,p.18.

Technical Abstract: Xanthomonas axonopodis pv. citri (Xac)-infected trees continued to occur in São Paulo commercial plantings previously subjected to eradication, indicating that removing all trees within a 30-m radius of known Xac-infected trees was insufficient to eradicate the disease within infected orchards. Post-eradication maps of Xac-infected and non-infected trees were collected from 98 commercial plantings where citrus canker reoccurred following tree removal. Those maps were interrogated to determine the distance from previously identified and removed infected trees and new Xac-infected trees beyond the 30-m radius of destruction used for eradication. The citrus canker-infected tree gradient decreased over distance and was well described by an inverse power law function, y = 31413.5x-1.186, r2 = 0.983. The calculated cumulative distribution of the frequency of counts of Xac-infected plants over distance was described well by the monomolecular model, y = (1 – (0.79)*exp(-(0.007)*x), r2 = 0.999 (Fig. 1A,B). Using this model, the distances necessary to circumscribe 90, 95, and 99 percent of the new diseased trees that occurred were 296, 396, and 623 m, respectively. These calculated distances were remarkably similar to distances found necessary to remove the same proportions of the population in residential areas in south Florida: 213 m (range 152-61 3m) , 335 m (range 213-773 m), and 594 m (range 427-899 m) for 90, 95, and 99 percent captures, respectfully (Gottwald et al., Phytopathology 92:361-377, 2002). This indicates that the same spatial processes that affected the spread of Xac in Florida likely affected the pathogen’s spread in Brazil as well.

Last Modified: 5/5/2015
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