LOW AVAILABILITY OF EFFICIENT FUNGICIDES FOR RICE BLAST CONTROL IN LOWLAND RICE CULTIVATION IN BRAZIL

Abstract

Rice cultivation is fundamental to Brazil's economy, which is the largest grain-producing country outside the Asian continent. However, several factors harm sustainable rice production, including diseases incidence. The blast is the major rice disease, and annually, losses caused by this disease would be sufficient to feed millions of people. Due to the complexity in rice blast management, fungicide application has been most used by rice growers, however, despite the high number of registered fungicides, is questioned the real efficiency in field conditions. This work aimed to analyze the effectiveness of fungicides in rice blast control and grain yield maintenance in irrigated rice. Experiments were carried out in a randomized block design, with four replications, in 2015/2016 and 2016/2017 crop seasons, at the Rio Grande do Sul Rice Experiment Station located in Cachoeirinha city, RS, Brazil. We tested the efficiency of nine fungicides registered in Brazil with different target sites for rice blast control. The analyzed variables were the Area Under the Disease Progress Curve (AUDPC) in leaves; neck blast incidence; panicle blast severity and grains yield. In general, only the tricyclazole and trifloxystrobin + tebuconazole fungicides were efficient in rice blast control with direct reflection on grain yield.