ABSTRACT
Leaf diseases of rice can compromise grain filling and spikelet maturation for accelerating the drying of grains and, consequently, reducing the industrial yield. The use of fungicide has the potential to reduce the damage from leaf diseases and increase the industrial yield. The aim of this study was to evaluate the number of fungicide application at different growth stages on the control of leaf diseases for multiple pathosystem (blast, brown spot and scald) and its relationship with the industrial yield (income benefit, whole and broken grains). The experiments were conducted in the growing seasons 2011/12 and 2012/13 in Rio do Oeste County, located at Alto Vale do Itajaí, Santa Catarina State. Rice cultivar SCS 116 Satoru was used. Experimental design was in randomized blocks with four replicates and six treatments constituted of applications of a mixture of fungicides difenoconazole and azoxystrobin, while one of the treatments (control) received no chemical application. Fungicide applications were performed at V8 vegetative stage and at the reproductive stages R0, R2, R4 and R6. Harvest was manually performed, obtaining 2m2 of the central area of each plot. One, two, three, four and five fungicide applications showed an average increase, compared to the control, in the two seasons, of 6%, 7.2%, 13.1%, 17.4% and 19.2% of the income benefit, 14.6%, 28.5%, 36.1%, 45% and 48.7% for whole grains, while the percentage of broken grains reduced by 4.4%, 13.2%, 21.7%, 35% and 41.4%, respectively.
Keywords
Oryza sativa; leaf diseases; leaf severity; income benefit