Efficacy of halosulfuron herbicide on purple nutsedge (Cyperus rotundus L.) and its selectivity to sugar cane plants (Saccharum spp.).

Abstract

Weed control in the sugar cane crop is basically herbicide dependent. The objective of this research was to evaluate the efficacy of halosulfuron for the control of purple nutsedge (Cyperus rotundus L.), which is one of the most important weed species infesting sugar cane fields, as well as its toxic potential to sugar cane plants, BR72454 variety. The experiment was set up according to a randomized complete block design, with nine treatments and six replications. The herbicides were applied as follows: halosulfuron (0.0375, 0.0562, 0.0750, 0.0937, 0.25, and 0.32 kg ha-) mixed with Gernamin T200® or Aterbane® surfactants, 0.5% v/v and 2,4-D (2.0 kg ha-), both applied in postemergence. The check treatments consisted of plots mechanically hoed and plots with no weed control. Halosulfuron doses of 0.0937, 0.25, and 0.32 kg ha- did away with at least 80% of the purple nutsedge population and the second year evaluations showed even higher levels of control, independently of the evaluation period. When the tuber population in the soil was examined, it was found that in the third year the halosulforon doses had reduced them by more than 92% and, in the fifth year, by more than 99%. 2,4-D was verified to have a low and variable effect on the control of purple nutsedge. Both herbicides seemed to be selective to sugar cane. Purple nutsedge competition did not reduce sugar cane productivity.Additional keywords: weed; chemical control; interference; productivity.