The orange rust caused by Puccinia kuehnii, is currently one of the most important diseases of sugarcane due to the potential damage to susceptible varieties. This study evaluated the effect of temperature on germination of uredospores. Uredospores were collected in the commercial field of sugarcane, variety SP 891115 in the city of Andirá (PR). After being removed from leaves, the uredospores underwent separation of impurities and placed in a solution of distilled water with Tween-20. The spores suspension was calibrated using a Neubauer chamber and plated an aliquot of 0.1 ml on the agar-water (1.5%). The plates were placed in BOD, at temperatures: 10, 15, 20, 25 and 30 º C in six incubation periods: 1, 3, 6, 12, 18, 24 hours, totaling 30 treatments with five replications. At the end of each period, germination was stopped by adding 0.1 ml of lactophenol. Each plate was divided into four fields and 50 spores were assessed in each field. Data on germination percentage were subjected to analysis of variance in a factorial 5x6 with the unfolding of interaction in orthogonal polynomials. By adjustment of mathematical model, the maximum germination occurred for the period of 12h at a temperature of 21ºC (R2 = 82%). For the incubation periods, the model estimated that in the curve of temperature 20ºC were required 14 hours (R2 = 65%) to reach maximum germination.
Epidemiology; incubation; environmental conditions
