Pre‐plant and in‐crop herbicide programs for prickly sida control in soybean

Abstract

Prickly sida (Sida spinosa L.) is emerging as a prevalent and troublesome weed in the Mid-South glyphosate-resistant (GR) soybean [Glycine max (L.) Merr.] cropping systems as reliance on residual herbicides has decreased. It emerges throughout the growing season and postemergence (POST) control has been reported to be variable. Combinations of residual herbicides applied pre-plant and at-planting followed by POST herbicides in-crop may be needed to maximize control. This research utilized separate studies to address the value of currently available residual herbicides applied pre-plant, at-planting, and POST in glyphosate-resistant soybean prickly sida management systems. At 35 days after application (DAA), prickly sida control from glyphosate plus 2,4-D pre-plant with flumioxazin plus chlorimuron-ethyl, flumioxazin plus pyroxasulfone, flumioxazin plus chlorimuron-ethyl plus thifensulfuronmethyl, metribuzin plus chlorimuron-ethyl or metribuzin plus sulfentrazone was 70-89% and similar among treatments. In a separate study, based on prickly sida control and density 21 days after late postemergence (LPOST) application, improvement in control was most affected by inclusion of glyphosate or glyphosate plus residual herbicides flumioxazin, chlorimuron-ethyl, and thifensulfuron-methyl at-planting.Weed control was not improved when residual herbicides chlorimuron-ethyl plus tribenuron-methyl were included pre-plant or when residual herbicides chlorimuronethyl, s-metolachlor, and fomesafen were applied with glyphosate POST. Late-season prickly sida control was as high as 93% following at-planting and POST applications that did not include residual herbicides. Soybean yield was maximized with glyphosate applied both at-planting and POST, whether or not residual herbicides flumioxazin, chlorimuron-ethyl, and thifensulfuron-methyl were included at-planting or residual herbicides chlorimuron-ethyl, s-metolachlor, or fomesafen were included POST. When averaged across at-planting and POST treatments, a 10% yield increase was observed when residual herbicides chlorimuron-ethyl and tribenuron-methyl were applied with glyphosate plus 2,4-D pre-plant compared with glyphosate plus 2,4-D alone.

Prickly Sida (Sida spinosa L.), Hemp Sesbania [Sesbania herbacea (Mill.) McVaugh], and Pitted Morningglory (Ipomoea lacunose L.) Response to Selective and Non-Selective Herbicide in Mississippi, USA

“…Prickly sida (Sida spinosa L.) has become a particularly problematic weed for agronomic cropping systems in the Mid-South region of the United States, especially in cotton (Gossypium hirsutum L.), soybean (Glycine max L.), corn (Zea mays L.), and peanut (Arachis hypogaea L.) (Korres et al, 2015a(Korres et al, , 2015b(Korres et al, , 2017Webster & Nichols, 2012). The credence of chemical herbicides to control this troublesome weed has decreased with its usage (Webster & Nichols, 2012;Copes et al, 2021). This bothersome weed reduces yields in many crops including soybean (Webster & Nichols, 2012).…”

“…It has been documented mentioned that prickly sida caused soybean yield reduction by 9-14% (Jeffery et al, 1976). The control of this weed species is difficult, especially in agronomic fields, due to its ability to emerge throughout the growing season, to thrive under crop canopy with reduced light, and its great capacity for seed production after the crop has been harvested (Copes et al, 2021). Currently, the most popular method to control prickly sida is by using chemical herbicides.…”

“…Application timing may be an important factor when applying herbicides to burndown prickly sida populations. In a soybean field study, it was found that late-season control of prickly sida was 93% with herbicide application at-planting and postemergence without the inclusion of any residual herbicide (Copes et al, 2021). In a study on preemergence herbicides and spray nozzle types found that the efficacy of imazethapyr in prickly sida increases under high residue levels (Ferguson et al, 2022).…”

Can pre- and/or post-emergent herbicide application affect soybean seed quality?

“…In grain farming, herbicides are often used in the off-season, primarily to manage difficult-to-control weeds, combining burndown with pre-emergent herbicides applied before planting (ALBRECHT et al, 2021). Dicotyledonous (dicot or broadleaf) weeds can be controlled using synthetic auxins, such as 2,4-D and dicamba (ASKEW et al, 2021;CANTU et al, 2021), among other broadleaf herbicides, including protoporphyrinogen oxidase (PPO) (COPES et al, 2021) or acetolactate synthase (ALS) inhibitors (KASPARY et al, 2021).…”