Location: Subtropical Plant Pathology Research
Title: ANNUAL AND POLYETIC PROGRESSION OF CITRUS CANKER ON TREES PROTECTED WITH COPPER SPRAYS Authors
|Behlau, Franklin -|
|Amorim, Lilian -|
|Belasque JR., Jose -|
|Bergamin Filho, Armando -|
|Leite JR., Rui Pereira -|
Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 3, 2010
Publication Date: September 3, 2010
Citation: Behlau, F., Amorim, L., Belasque Jr., J., Bergamin Filho, A., Leite Jr., R., Gottwald, T.R. 2010. ANNUAL AND POLYETIC PROGRESSION OF CITRUS CANKER ON TREES PROTECTED WITH COPPER SPRAYS. Plant Pathology. DOI: 10.1111/j.1365-3059.2010.02344.x Interpretive Summary: Citrus canker remains a disease of considerable concern to the citrus industry of Florida, where is endemic, and to the citrus industries of Texas and California where the continual possibility of introduction exists. The presence of citrus canker also greatly affects market access among states in the US and abroad. Therefore intricate knowledge of the most efficacious combinations of disease control strategies for citrus canker are paramount to achieving the highest yields possible in the presence of the disease in maintaining the best market access. A comforting factor has been the presence of the Asian leafminer, an insect pest of citrus, which interacts with and exacerbates citrus canker disease when it is present. This research study examined the interaction of leafminer control, citrus canker disease control via bactericidal compounds, and the use of windbreaks to reduce disease spread. It was found that the amount of disease decreased over time and all plots or bactericidal sprays of copper were used in that windbreaks did not have any effect on controlling the disease. This may have been because the windbreaks were not as tall as needed to completely occlude wind from the plots. This information will be made available to US citrus growers who can hopefully take advantage of it in designing citrus canker disease control strategies to maximize profit and market access.
Technical Abstract: : Mathematical models are important tools for comparative analysis of epidemics. In this paper, parameters obtained from the mathematical model that best fitted to the annual progress curves of citrus canker incidence were used to evaluate the effect of copper sprays and windbreaks on the annual and polyetic disease progress, in the presence of the Asian citrus leafminer. The experiment was carried out in a commercial grove with endemic infection of citrus canker located in the Northeastern region of Paraná state, Brazil. The disease incidence, estimated through the proportion of symptomatic leaves, was evaluated monthly during three consecutive years. Nonlinear monomolecular, logistic and Gompertz models were fitted to monthly disease incidence data for each treatment for three consecutive years. The logistic model provided the superior estimate to for all years and treatments evaluated, and estimated model parameters were used to construct polyetic disease dynamic graphs. Decreased annual incidence of citrus canker resulted for all plots but was most pronounced for citrus plots treated with copper sprays, whereas, windbreaks had no effect on the temporal progress of the disease. In the second year, citrus plots not treated with copper had the maximum asymptote of disease incidence and estimated initial (residual from pervious year) disease incidence (y0) 90% and >10 times higher, respectively, in comparison to citrus plots periodically sprayed with the copper bactericide, irrespective of the presence of windbreaks.