Interaction between partial genetic resistance and fungicides in the control of soybean Asian rust

Abstract

The objective of this work was to analyze the interaction between cultivars and fungicides for soybean Asian rust control, in two sowing times. The experiment was carried out in field conditions, from September 2005 to May 2006. The following traits were analyzed: incidence, severity (percentage of infected leaf area and visual grading of the plot), number of pustules per square centimeter, weight of one thousand seeds and yield. The area under the disease progress curve (AUDPC) was calculated for disease data. Significant effects were observed for cultivars, fungicides, and the interaction between these factors for AUDPC, as well as for weight of one thousand seeds and yield. The cultivars IAC-100, Potenza and UFUS-Impacta, in both sowing times, presented partial resistance to Asian rust, which was highlighted by the low values of AUDPC. The triazole group fungicide cyproconazole and its mixture with the strobilurin group fungicide azoxystrobin were effective on Asian rust control.