Phytotoxicity in two sugarcane cultivars in the initial development as affected by selectivity to herbicides

ABSTRACT Sugarcane is a crop of great importance for human consumption, either for the production of sucrose or for the production of ethanol fuel. The objective of this work was to evaluate the phytotoxicity caused by the herbicides, the agronomic components in two sugarcane cultivars, at five evaluation times, during the 12-month and 18-month cultivation periods. The experimental design was randomized blocks with four replicates, in a 10 x 2 factorial scheme, with nine herbicides (tembotrione, mesotrione, clomazone, saflufenacil, 2,4 dichlorophenoxyacetic, fluroxypyr + picloram, metribuzin, isoxaflutole, sulfentrazone), two sugarcane cultivars (RB006995 and RB036153), and five evaluation times (7, 14, 21, 28 and 35 days after application – DAA). The most phytotoxic herbicides for the 12-month cultivation period in the cultivars RB036153 and RB006995 were clomazone and sulfentrazone. For 18-month cultivation period, the herbicides isoxaflutole, clomazone and sulfentrazone were the most phytotoxic, mainly for the cultivar RB006995. For most herbicides, phytotoxicity decreased along the days after application. The most selective herbicides for both cultivars and cultivation periods were tembotrione, mesotrione and fluroxypyr + picloram.