Weed Control J 2021; 20: e202100756

Research Article

Control of sourgrass with graminicide herbicides after different water restriction periods

DOI: 10.7824/wcj.2021;20:00756

Abstract

Background

Acetyl-CoA carboxylase (ACCase) enzyme inhibitors are post-emergent herbicides recommended for the control of sourgrass ( Digitaria insularis ). Water stress can influence the physiological processes and the effectiveness of these herbicides in weeds.

Objective

The objective of this work was to evaluate the effectiveness of ACCase enzyme inhibitors in the control of sourgrass after different periods of water restriction.

Methods

The treatments were organized in a factorial scheme (8×4). Factor A was composed of periods of water suspension before herbicide application (0; 2; 4; 6; 8; 10; 12 and 14 days). Factor B was composed of the herbicides cletodim (144 g a.i. ha-1), quizalofop-P-tefuril (72 g a.i. ha-1) and [cletodim + quizalofop-P-ethyl] (144 + 72 g a.i. ha-1), in addition to untreated treatment. The evaluated variables were the control of sourgrass at 14, 28 and 42 days after the application of treatments (DAT) and the dry shoot mass at 42 DAT.

Results

When applied without water suspension, the control was greater than 80% for all herbicides. However, with 14 days of water suspension, the control was reduced to 15% for the herbicide quizalofop-P-tefuril and to 29% for the association [clethodim + quizalofop-P-ethyl]. The effectiveness of the clethodim was less influenced by water restriction, with 56.6% of control when applied after 14 days of water restriction.

Conclusions

The effectiveness of ACCase inhibitors on the control of sourgrass is considerably reduced with the reduction of soil moisture. Clethodim was more effective in drier soil, although less than satisfactory.