Effect of cover-crop biomass, strip-tillage residue disturbance width, and PRE herbicide placement on cotton weed control, yield, and economics

Abstract

Conservation tillage adoption continues to be threatened by glyphosate and acetolactate synthase-resistant Palmer amaranth and other troublesome weeds. Field experiments were conducted from autumn 2010 through crop harvest in 2013 at two locations in Alabama to evaluate the effect of integrated management practices on weed control and seed cotton yield in glyphosate-resistant cotton. The effects of a cereal rye cover crop using high or low biomass residue, followed by wide or narrow within-row strip-tillage, and three PRE herbicide regimes were evaluated. The three PRE regimes were: 1) pendimethalin at 0.84 kg ae ha-1 plus fomesafen at 0.28 kg ai ha-1 applied broadcast, 2) pendimethalin plus fomesafen applied banded on the row, or 3) no PRE. Each PRE treatment was followed by (fb) glyphosate (1.12 kg ae ha-1) applied POST fb a LAYBY applications of diuron (1.12 kg ai ha-1) plus MSMA (2.24 kg ai ha-1). Low residue plots ranged in biomass from 85 to 464 kg ha-1, while high biomass plots ranged from 3119 to 6929 kg ha-1. In most comparisons, surface disturbance width, residue amount, and soil applied herbicide placement did not influence within-row weed control; however, broadcast PRE resulted in increased carpetweed, large crabgrass, Palmer amaranth, tall morningglory, and yellow nutsedge weed control in row middles compared to plots receiving banded PRE. In addition, high residue increased carpetweed, common purslane, large crabgrass, Palmer amaranth, sicklepod, and tall morningglory weed control between rows. Use of banded PRE herbicides resulted in equivalent yield and revenue in four of six comparisons compared to those with broadcast PRE herbicide application; however, this would likely result in many between row weed escapes. Thus, conservation tillage cotton would benefit from broadcast soil-applied herbicide applications regardless of residue amount and tillage width when infested with Palmer amaranth and other troublesome weed species.

Impact of integrated weed management practices on cotton economics and Palmer amaranth (Amaranthus palmeri) populations

“…Consequently, the cereal rye biomass and groundcover were greatly reduced when compared to 2020, where the cereal rye in 2019 measured less than 40 cm in height and the cereal rye in 2020 was approximately 150 cm tall. Cereal rye biomass at planting was not measured in 2019, but biomass of the cereal rye at planting in 2020 averaged 4,500 kg ha −1 , which is similar to biomass recovered in other studies where weed emergence was suppressed at biomass levels ≥ 3,100 kg ha −1 (Palhano et al 2018;Price et al 2021). Differences in herbicide programs between 2019 and 2020 can be attributed to differences in climatic conditions between the two years (Figure 2).…”

“…In 2020, the use of cereal rye improved cotton yields by 220 kg ha −1 and profit by US$280 ha −1 . The improvement in cotton yield because of cereal rye is similar to findings in Alabama and Tennessee, where the use of a cover crop did improve cotton yields in some years, while there were negligible differences in others (Price et al 2021;Zhou et al 2017). Findings from other studies in Arkansas and Texas suggested that the use of cereal rye cover crops had no effect on cotton yield or net returns (DeLaune et al 2020;DeVore et al 2012).…”

“…Other studies have found that the use of cereal rye cover crops may improve cotton yield and partial returns in some instances, while in others, there are no differences (DeLaune et al 2020;DeVore et al 2012;Price et al 2021). The use of cereal rye cover crops reduces cotton yield in some instances, primarily because of losses in cotton stand due to allelopathy from cereal rye and difficult planting conditions (Palhano et al 2018;Price et al 2021). In the southeastern United States, the use of deep tillage with a moldboard plow for weed management has had minimal effect on cotton yield, especially when paired with cereal rye cover crops.…”

“…A long-term study conducted over 29 yr in western Tennessee found that the cash crop yield benefit of cereal rye cover crops was not enough to offset the cost of implementation, thus resulting in a net negative compared to not utilizing cereal rye cover crops at all (Zhou et al 2017). Other studies have found that the use of cereal rye cover crops may improve cotton yield and partial returns in some instances, while in others, there are no differences (DeLaune et al 2020;DeVore et al 2012;Price et al 2021). The use of cereal rye cover crops reduces cotton yield in some instances, primarily because of losses in cotton stand due to allelopathy from cereal rye and difficult planting conditions (Palhano et al 2018;Price et al 2021).…”

Integrating cover crops and herbicides for weed control in soybean

“…Included in integrated strategies is an increased use of tillage to bury weed seeds at depths beyond successful germination and emergence, which threatens adoption and retention of conservation systems (Price et al 2011(Price et al , 2016. However, the adoption of cover crops continues to gain attention because of their weed-suppressive attributes, including disrupting the establishment and growth of weeds while maintaining crop yields (Aulakh et al 2015;Norsworthy et al 2010Norsworthy et al , 2011Price et al 2011Price et al , 2016Price et al , 2021. Weed suppression after cover crop termination has been shown primarily to be due to plant residue biomass that prevents seed germination and establishment by altering light quantity at the soil surface and providing a physical barrier (Norsworthy et al 2011;Price et al 2006;Teasdale 2018).…”