Published online by Cambridge University Press: 20 January 2017
The sugarcane varieties ‘LCP 85-384’, ‘HoCP 85-845’, and ‘LCP 82-089’ were treated in the plant cane crop (first production year) with various combinations of azafeniden preemergence (PRE) at 0.56 or 0.84 kg ai/ha after planting in September/October, postemergence (POST) at 0.56 kg/ha in spring (March), and semidirected at 0.42 kg/ha after the final cultivation at layby in May. In the first ratoon crop (second production year) azafeniden was reapplied in spring and at layby. Herbicide programs were compared with the standard program of atrazine plus pendimethalin PRE after planting, POST applications of diuron plus pendimethalin in spring, and atrazine plus pendimethalin semidirected at layby. Crop injury was negligible for all herbicide treatments applied after planting. Azafeniden injured sugarcane 30 to 33% when applied POST in spring, and injury was most severe in plant cane and first ratoon HoCP 85-845 when they were considerably taller and had more foliage at application compared with the other varieties. Injury from azafeniden following layby application ranged from 9 to 19% in plant cane and first ratoon crops. Multiple applications of azafeniden during the plant cane and first ratoon years did not reduce stalk height, population, sugarcane yield, or sugar yield for any of the varieties when compared with the standard herbicide program.