Differential response of rice cultivars to fungicide application in relation to blast

Abstract

The response of five early (Batatais, Dourado Precoce, Edith Long, IAC 25 and Pratão Precoce) and eight medium duration (Fernandes, IAC 47, IAC 1246, IAC 5544, IPEACO 562, Montanha Liso, Pratão and Tainan) upland rice cultivars to fungicide application in relation to blast control as well as grain yield was evaluated based on the protected and unprotected plots of the field experiments conducted during three years. Plots were protected with fungicidal sprays alternating benomyl with kasugamicin at seven to twelve-day interval. The degree of leaf blast control was related to area under disease progress curves. The response to fungicide application in relation to disease control and grain yield was greater in cultivars exhibiting relatively higher values for areas under disease progress curves. The cultivars Edith Long and IAC 25 among the early ones and IPEACO 562, IAC 1246 and IAC 47 among the medium duration ones exhibited high degree of resistance to leaf blast. The average grain yields of the protected and unprotected plots were superior in cvs. IAC 47, IAC 25 and Batatais.