The efficacy of windbreaks in reducing the spread of citrus canker caused by Xanthomonas campestris pv. citri

The effects of windbreaks and copper (Cu) bactericide applications alone and in combination on the spread of Xanthomonas campestris pv. citri (Xcc) and incidence of citrus canker were tested in Argentina during 1990 and 1991. The monomolecular temporal model was the most appropriate for describing citrus canker disease progress. The monomolecular rate of disease progress was significantly less for Cu bactericide and windbreaks compared to an untreated control; however, more significant reductions of disease progress occurred with the use of windbreaks alone or in combination with Cu bactericide. Disease gradients were significantly less extensive when a Cu bactericide was used compared to untreated control plots, with significant additional reductions when windbreaks were employed. Temporal and spatial analyses of citrus canker epidemics indicated that the use of windbreaks was a more effective disease control strategy than the use of a Cu bactericide and significantly reduced temporal disease increase and spatial spread of citrus canker over time. As expected, Cu bactericide did reduce disease increase and spread but not as effectively as windbreaks. Temporal increase and spatial spread of disease associated with A-strain and B-strain of Xcc in lemon plantings were not significantly different indicating that for a susceptible host such as lemon, the two strains are equivalent in virulence and epidemiological potential.