Optimization of foramsulfuron doses for post-emergence weed control in maize (Zea mays L.)

Euro Pannacci

doi:10.5424/sjar/2016143-9436

Abstract

Four field experiments were carried out from 2011 to 2014 in order to evaluate the effects of foramsulfuron, applied at the recommended (60.8 g a.i./ha) and reduced doses (1/3 and 2/3), on the efficacy against several of the most important weeds in maize. For each “year-weed” combination, dose-response curves were applied to estimate the dose of foramsulfuron required to obtain 90% and 95% weed control (ED90 and ED95). Foramsulfuron phytotoxicity on maize and crop yield were assessed. Foramsulfuron at 1/3 of the recommended dose (20.3 g a.i./ha) provided 95% efficacy against redroot pigweed (Amaranthus retroflexus L.), green foxtail (Setaria viridis (L.) Beauv.), wild mustard (Sinapis arvensis L.) and black nightshade (Solanum nigrum L.). Velvetleaf (Abutilon theophrasti Medik.), common lambsquarters (Chenopodium album L.) and barnyardgrass (Echinochloa crus-galli (L.) Beauv.) were satisfactorily controlled (95% weed efficacy) with ED95 ranged from 20 to 50 g/ha of foramsulfuron (about from 1/3 to 5/6 of the recommended dose) depending on growth stage. The recommended dose was effective against pale smartweed (Polygonum lapathifolium L.) at 2-4 true leaves (12-14 BBCH scale), but this dose did not kill plants larger than 2-4 true leaves. The ranking among weed species based on their susceptibility to foramsulfuron was: redroot pigweed = green foxtail = wild mustard = black nightshade > velvetleaf = common lambsquarters = barnyardgrass > pale smartweed. Dose of foramsulfuron can be reduced below recommended dose depending on weed species and growth stage. Foramsulfuron showed a good crop selectivity and had no negative effect on maize yield.

Highlights

Maize (Zea mays L.) is one of the most widely planted crop in the world and its production is increasing globally
The four field experiments showed that weed susceptibility against foramsulfuron can be quantified by dose-response curves, and that weeds can be classified with respect to their susceptibility via ED90 and ED95 values
The ranking among weed species based on their sensitivity to foramsulfuron was: redroot pigweed = green foxtail = wild mustard = black nightshade > velvetleaf = common lambsquarters = barnyardgrass > pale smartweed

Summary

Introduction

Maize (Zea mays L.) is one of the most widely planted crop in the world and its production is increasing globally. System (IWMS), is to apply the lowest dose needed for biologically effective weed control (Swanton & Weise, 1991; Kudsk & Streibig, 2003; Blackshaw et al, 2006), low doses can increase risk of polygenic resistance (Neve & Powles, 2005; Busi et al, 2011). Several studies have demonstrated satisfactory weed control and acceptable crop yields, when herbicides are used at lower than normally recommended doses (Devlin et al, 1991; Zhang et al, 2000; Barros et al, 2009; Pannacci & Covarelli, 2009). The determination of MDRE requires dose-response studies for each “herbicide-weed species” under various environmental conditions (Kudsk & Kristensen, 1992; Pannacci & Covarelli, 2009)

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