Aiming to validate a forecast model with different severity levels compared to conventional spraying to control tomato bacterial spot, experiments were conducted in Caçador, SC, during the crop seasons 2006/07, 2007/08 and 2009/10. The spraying regimens were established according to the predicted severity (SP=severity percentage/100) of 0.05, 0.10, 0.15 and 0.25 based on the model SP = 0.0001538 * {[(x-8)(2.4855647)* ((32-x)(0.7091962))} * {[0.64289/(1+21.26122 * exp (-0.12435*y)} and the conventional system (spraying at every 5 and 7 days and twice a week, depending on the crop cycle). There was no significant difference between treatments for productivity and disease incidence in fruits. In the area under the disease progress curve (AUDPC), there was a reduction of 25.71% in SP 0.15 for the same number of weekly applications. In 2007/08 and 2009/10 cycles, treatments did not differ as to AUDPC, but in the forecast system with SP 0.15 the number of sprays was more than 50% lower, compared to the system with two weekly applications.
Solanum lycopersicum; plant disease forecaster; epidemiology; Xanthomonas spp
