Prevalence, incidence and distribution of citrus variegated chlorosis in Bahia, Brazil

Citrus variegated chlorosis (CVC) is one of the most important diseases for Brazilian citricultureIt is caused by Xylella fastidiosa subsp. pauca, a xylem limited, cycadelid and budwood transmitted bacterium. In Bahia, the second most important citrus region in Brazil, CVC has been present since 1997. Our objectives were to characterize the regional spatial pattern of CVC and to establish a relationship between epidemiological variables and horticultural practices, as well as to evaluate whether control measures used so far have been effective and, based on that, to conceive suitable control measures. A series of surveys were performed in two regions of Bahia State (Recôncavo Baiano and Litoral Norte), along with a survey of horticultural and control practices associated with sampled groves. CVC was restricted to Litoral Norte region, especially to three municipalities along the border between Bahia and Sergipe StatesThe mean CVC incidence in these municipalities followed a gradient, higher in the countryside and decreasing along the coast. Presence and dissemination of CVC was related to poor nursery practices, a massive use of a susceptible orange variety, and an extreme concentration of orange groves in high incidence municipalities, as well as to the absence of specific CVC control. Considering that CVC was not found in Recôncavo Baiano, this region could be considered a "CVC free zone" by the local government.