Peanut (Arachis hypogaea L.) Response to Glyphosate plus Dicamba Combinations

W James Grichar,Todd A Baughman,Peter A Dotray

doi:10.24297/jaa.v12i.9016

Abstract

Field studies were conducted in south and the High Plains of Texas as well as in southwestern Oklahoma during the 2014 and 2015 growing seasons to evaluate the effects of glyphosate plus dicamba combinations (1/16 X to 1 X of the 1.68 kg ae ha-1 rate) applied 30, 60, and 90 days after planting (DAP) on Spanish (Oklahoma) and runner (Texas) peanut. Rates were established to evaluate sub-labeled drift and direct application of a 1 X rate. Peanut stunting and death were more prevalent at the 30 and 60 DAP application while peanut were more tolerant of the 90 DAP application. In south Texas, peanut yields were reduced in both years when rates of ¼ X or greater were applied 30 and 90 DAP while rates of 1/8 X or greater reduced yield when applied 60 DAP. At the High Plains location, peanut yields were consistently reduced with rates of ½ X or greater applied 30 and 90 DAP and ¼ X or greater applied 60 DAP. In Oklahoma, peanut yield were consistently reduced with rates of ¼ X or greater applied 30 and 60 DAP and 1/16 X or greater when applied 90 DAP. Peanut grade was more affected by the 60 and 90 DAP application than the 30 DAP application.

Highlights

During the past twenty years the use of glyphosate-resistant crop production systems have been adopted and used extensively in various regions of the US [1]
Peanut injury for plants sprayed 30 and 60 days after planting (DAP) consisted of leaf epinasty, chlorosis, https://rajpub.com/index.php/jaa stunting, and death while injury for plants sprayed 90 DAP consisted of leaf chlorosis and necrosis plus some plant death
In 2014, peanut injury was greater than the untreated check (0 X) with glyphosate plus dicamba rates of 1/8 X or greater when applied 30 and 60 DAP or 1⁄4 X rate or greater when applied 90 DAP (Table 2)

Summary

Introduction

During the past twenty years the use of glyphosate-resistant crop production systems have been adopted and used extensively in various regions of the US [1]. Glyphosate-resistant weeds, Amaranthus species, have become an issue across all the US corn and cotton producing areas [3]. Estimates are that more than 1.2 million ha of cropland in the US are affected by glyphosate-resistant Amaranthus species [3]. Wats.) has been shown to reduce lint yield by 57% when growing at a density of 10 plants per 9.1 m row-1 [4]. With Palmer amaranth growing at densities greater than six plants per 9.1 m row-1, cotton may not be harvestable due to the potential for damage to harvest equipment [4]. A study by Smith et al [5] found that Palmer amaranth densities of 650 to 3260 plants ha-1 in dryland stripper-harvested cotton increased harvesting time by 2- to 3.5fold

Objectives

Methods

Results

Conclusion