Control of Italian ryegrass and Alexandergrass in corn using different corn sowing date, pre- and post-emergent herbicides

Cristiano Piasecki,Luiz Francisco Bellini,Leandro Vargas,Gilmar José Picoli Junior,Ramiro Fernando Lopez Ovejero,Dirceu Agostinetto

doi:10.1590/1678-4499.20190362

Cristiano Piasecki, Luiz Francisco Bellini + Show 4 more

Open Access

https://doi.org/10.1590/1678-4499.20190362

Copy DOI

Abstract

Glyphosate-resistant (GR) Italian ryegrass (LOLMU) and Alexandergrass (URPLA) are troublesome weeds in corn cropping systems in Southern Brazil. The emergence pattern of those weeds is not uniform and may change according to the season’s environmental characteristics. Also, herbicide resistance has been diminishing the success of the weed control programs. The objectives of this study were to evaluate the influence of corn-sowing date on LOLMU and URPLA densities and their control provided by pre- and post-emergent herbicides. Field trials were conducted in two crop seasons in Southern Brazil consisting of three corn sowing date (August, September, and October) and the application of atrazine + S-metolachlor (residual) in corn pre-emergence in different post-emergence weed control programs with glyphosate, ammonium-glufosinate, nicosulfuron, and atrazine. The results indicated that the sowing date had a significant influence on LOLMU and URPLA densities. Corn sown in the earliest period was exposed to a higher LOLMU density, whereas corn sown in the latest period had a higher density of URPLA. Also, the application of residual herbicide at corn pre-emergence reduced both weed species densities and decreased the pressure for the control of glyphosate-resistant LOLMU for the post-emergence herbicides. The use of residual herbicides in corn pre-emergence is an efficient strategy to be considered in the LOLMU and URPLA control programs, followed by post-emergence application of glyphosate, ammonium-glufosinate, atrazine, and nicosulfuron.

Highlights

Corn is an important cash crop in the Rio Grande do Sul state, Brazil
The objectives of this study were to evaluate the influence of corn-sowing date on LOLMU and Urochloa plantaginea (Link) R.D. Webster] (URPLA) densities and their control provided by pre- and post-emergent herbicides
Field trials were conducted in two crop seasons in Southern Brazil consisting of three corn sowing date (August, September, and October) and the application of atrazine + S-metolachlor in corn pre-emergence in different post-emergence weed control programs with glyphosate, ammonium-glufosinate, nicosulfuron, and atrazine

Summary

Introduction

Corn is an important cash crop in the Rio Grande do Sul state, Brazil It is cultivated in an area of approximately 1 million hectares and produces nearly 6,000 tons per year (CONAB 2018). In this state, the significant part of the corn sowing window ranges from August to October, but it can be stretched out until December in some regions. Italian ryegrass is a C3 annual grass whose reproduction occurs by seeds, which can germinate, emerge, and establish over a range of environmental conditions (Bond et al 2014; Roman et al 2004).

Objectives

Methods

Results

Conclusion