Interaction of dicamba, fluthiacet-methyl, and glyphosate for control of velvetleaf (Abutilon theophrasti) in dicamba/glyphosate–resistant soybean

Jose H S De Sanctis,Amit J Jhala

doi:10.1017/wet.2021.40

Abstract

AbstractVelvetleaf is an economically important weed in agronomic crops in Nebraska and the United States. Dicamba applied alone usually does not provide complete velvetleaf control, particularly when velvetleaf is taller than 15 cm. The objectives of this experiment were to evaluate the interaction of dicamba, fluthiacet-methyl, and glyphosate applied alone or in a mixture in two- or three-way combinations for velvetleaf control in dicamba/glyphosate–resistant (DGR) soybean and to evaluate whether velvetleaf height (≤12 cm or ≤20 cm) at the time of herbicide application influences herbicide efficacy, velvetleaf density, biomass, and soybean yield. Field experiments were conducted near Clay Center, NE in 2019 and 2020. The experiment was arranged in a split-plot with velvetleaf height (≤12 cm or ≤20 cm) as the main plot treatment and herbicides as subplot treatment. Fluthiacet provided ≥94% velvetleaf control 28 d after treatment (DAT) and ≥96% biomass reduction regardless of application rate or velvetleaf height. Velvetleaf control was 31% to 74% at 28 DAT when dicamba or glyphosate was applied alone to velvetleaf ≤20 cm tall compared with 47% to 100% control applied to ≤12-cm-tall plants. Dicamba applied alone to ≤20-cm-tall velvetleaf provided <75% control and <87% biomass reduction 28 DAT compared with ≥90% control with dicamba at 560 g ae ha−1 + fluthiacet at 7.2 g ai ha−1 or glyphosate at 1,260 g ae ha−1. Dicamba at 280 g ae ha−1 + glyphosate at 630 g ae ha−1 applied to ≤20-cm-tall velvetleaf resulted in 86% control 28 DAT compared with the expected 99% control. The interaction of dicamba + fluthiacet + glyphosate was additive for velvetleaf control and biomass reduction regardless of application rate and velvetleaf height.

Highlights

Velvetleaf is an invasive weed native to China (Sattin et al 1992)
The treatments were arranged in a split-plot design with four replications; the main plot consisted of velvetleaf heights (≤12 cm or ≤20 cm), and the subplot consisted of herbicide treatments
The interaction was significant for velvetleaf height-by-herbicide treatment for velvetleaf control estimates, density, and biomass reduction; treatment means are presented within each velvetleaf height (≤12 cm or ≤20 cm)

Summary

Introduction

Velvetleaf is an invasive weed native to China (Sattin et al 1992). It was introduced to North America in the 17th century primarily for fiber production (Spencer 1984). Toole and Brown (1946) reported up to 48% viability of velvetleaf seeds after 39 yr of seed burial. Velvetleaf seed viability after 17 yr of burial was reported at 25% and 35% in eastern and western Nebraska, respectively (Burnside et al 1996). The allelopathic effect of velvetleaf plant extract on seed germination and seed root elongation was reported in soybean (Bhowmik and Doll 1982, Colton and Einhellig 1980), corn (Zea mays L.) (Bhowmik and Doll 1982), alfalfa (Medicago sativa L.) (Gressel and Holm 1964), radish (Raphanus sativus L.) (Gressel and Holm 1964), turnip [Rapistrum rugosum (L.) All.] (Elmore 1980; Gressel and Holm 1964), and cress (Lepidium sativum L.) (Sterling et al 1987)

Objectives

Methods

Results