Abstract
ABSTRACT ‘Pêra’ sweet orange is the most important citrus cultivar in Brazil, but it is highly susceptible to Citrus tristeza virus (CTV), the causal agent of citrus tristeza disease. In this study, we evaluated the severity of citrus tristeza disease and its relation with the agronomic performance of seven cultivars and six selections of ‘Pêra’ sweet orange under field conditions in the North and Northwest regions of the State of Paraná, Brazil. The citrus tristeza disease severity was determined based on symptoms of stem pitting. The vegetative growth assessed in trees of all four locations for the 2012 season, and in two field plots for the 2011, 2012 and 2013 harvests, respectively. The cultivar ‘IPR 153’ (Bianchi) had the best performance concerning stem pitting severity, while Selection 27 was among the ones with the highest rate of vegetative growth. Further, Selections 27 and 12, and the cultivar ‘Vimusa’ had the largest fruit yields. Based on correlation analysis, stem pitting symptoms severity was negatively correlated with vegetative growth and fruit yield. Furthermore, environmental conditions may have played an important role in the severity of citrus tristeza disease and consequently on the agronomic performance of the cultivars and selections of ‘Pêra’ sweet orange in the North and Northwest regions of the State of Paraná.
Highlights
Abstract - ‘Pêra’ sweet orange is the most important citrus cultivar in Brazil, but it is highly susceptible to Citrus tristeza virus (CTV), the causal agent of citrus tristeza disease
In Brazil, the damage caused by the disease is usually associated with stem pitting, which results from the development of a mass in the phloem parenchyma cells that penetrates into the xylem, causing vessel malformation and even destruction of the xylem vessels and parenchyma (TANAKA et al, 2009)
Based on each location individually, the lowest stem pitting severity was observed for the trees in the plot of Cambé, with 1.86 disease severity score, while the highest level was for the trees in Arapongas, with an average of 2.70 on stem pitting severity (Table 1)
Summary
Abstract - ‘Pêra’ sweet orange is the most important citrus cultivar in Brazil, but it is highly susceptible to Citrus tristeza virus (CTV), the causal agent of citrus tristeza disease. We evaluated the severity of citrus tristeza disease and its relation with the agronomic performance of seven cultivars and six selections of ‘Pêra’ sweet orange under field conditions in the North and Northwest regions of the State of Paraná, Brazil. Environmental conditions may have played an important role in the severity of citrus tristeza disease and on the agronomic performance of the cultivars and selections of ‘Pêra’ sweet orange in the North and Northwest regions of the State of Paraná. A main restriction for planting ‘Pêra’ sweet orange in Brazil is the susceptibility to Citrus tristeza virus (CTV), the causal agent of citrus tristeza disease (MÜLLER et al, 1999, SALIBE et al, 2002). It does not usually kill the tree, the disease reduces tree vigor and production, resulting in significant economic losses (DAWSON et al, 2013)
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