Validation of two forecast systems to control tomato late blight in Caçador region, SC, Brazil

Abstract

The MacHardy’s system developed in New Hampshire, USA, and the Maschio & Sampaio’s system developed in Colombo, PR, were compared to the traditional tomato late blight control system in Caçador, SC, Brazil. The forecast systems allowed a reduction in the use of fungicides from 30% to 54,6% with MacHardy’s model and from 20% to 40% with Maschio & Sampaio’s model compared to the traditional one. The yield of both
cultivars Carmem and Santa Clara did not differ among the three systems. The severity of the disease in the first
harvest was significantly higher for cultivar Santa Clara with traditional control, but there was no difference in the severity among forecasting models. In the second harvest there was no difference in the severity among the treatments. The forecast models allowed to delay the first spray from two to four weeks, when compared to the traditional system.