Part of the book: Herbicides
Part of the book: Herbicides
Field studies were conducted from 2006 to 2010 under weed-free conditions in south Texas and in the Texas High Plains to determine sesame tolerance to applied postemergence-directed herbicides. Injury was greatest when herbicides were applied to 15 cm of the main stem compared to herbicide applications made to 5 cm of the main stem height. Glyphosate at 0.84 kg ae/ha and pyrithiobac-sodium at 0.07 kg ai/ha resulted in the greatest sesame stunting (28–90%) when applied up to 15 cm main stem height, while carfentrazone-ethyl, flumioxazin, and imazethapyr caused greatest injury when applied to 5 cm of the main stem. When glyphosate was applied up to 5 cm main stem height, sesame injury was 20% or less. Glyphosate applied up to the 15 cm stem height and pyrithiobac-sodium applied 5 and 15 cm stem height consistently reduced sesame yield when compared with the nontreated control. Acetochlor, diuron, fluometuron, and prometryn did not cause any sesame stunting. Carfentrazone-ethyl, diuron, flumioxazin, imazethapyr, propazine, pyraflufen-ethyl, linuron, and linuron plus diuron reduced sesame yield in at least one year in south Texas.
Part of the book: Herbicides
Field studies were conducted to evaluate control of Amaranthus species and other weeds in corn and cotton. In corn, Palmer amaranth control was at least 90% with preemergence applications of fluthiacet‐methyl plus pyroxasulfone, atrazine plus either acetochlor, alachlor, dimethenamid‐P, S‐metolachlor, or S‐metolachlor plus mesotrione, saflufenacil plus dimethenamid‐P, and S‐metolachlor plus mesotrione. When using postemergence herbicides applied to Palmer amaranth less than 5 cm tall, atrazine, prosulfuron, and topramezone alone or the combinations of atrazine plus S‐metolachlor plus glyphosate, diflufenzopyr plus dicamba, dimethenamid plus glyphosate, halosulfuron‐methyl plus dicamba, mesotrione plus S‐metolachlor plus glyphosate, pyroxasulfone plus glyphosate, and thiencarbazone‐methyl plus tembotrione provided at least 91% control. In cotton, pyrithiobac applied preemergence resulted in no greater than 63% of control of Palmer amaranth and common waterhemp at the early season rating. Pendimethalin applied preemergence provided varied levels of control of common waterhemp. Trifluralin, applied preplant incorporated, consistently provided at least 86% or greater control of both species. A decreased level of control of both Palmer amaranth and common waterhemp was observed with pendimethalin applied preemergence followed by pyrithiobac‐applied early postemergence and followed by glufosinate applied mid‐post. Systems which included an early postemergence and mid‐postemergence application of glyphosate plus 2,4‐d choline provided at least 94% season‐long Palmer amaranth control.
Part of the book: Herbicide Resistance in Weeds and Crops
Field studies were conducted for 2 years in the High Plains of Texas (34.1826o N, 101.9505o W) and in South Texas (29.1634o N, 97.0725o W) to evaluate weed control when using different adjuvants with commonly used peanut herbicides. In the High Plains, Amaranthus palmeri L. control with acifluorfen, imazapic, lactofen, and 2,4-DB at the 1X dose improved with the use of an adjuvant over no adjuvant. A. palmeri control with imazethapyr was similar to that seen with imazapic and lactofen with the exception of the 1/2X rate of imazethapyr, which showed improved control with Agridex over the use of no adjuvant or Induce in 1 year, while Induce was better than no adjuvant or Agridex in the other year. In 1 year in South Texas, A. palmeri control with imazapic at the 1X dose was ≥73% with/without an adjuvant. In another year, the 1X dose of imazapic controlled A. palmeri 64% without an adjuvant, while the addition of Cide Kick II resulted in 83% control. An adjuvant did not improve A. palmeri control with lactofen or Cucumis melo L. control with either imazapic or lactofen. Urochloa texana (Buckl.) control with clethodim at the 1X dose was not improved by the addition of an adjuvant in either year. U. texana control was not improved when using the 1X dose of fluazifop-P with any adjuvant.
Part of the book: Legume Crops
Harvest aids are traditionally used to desiccate weeds to improve crop quality and harvest efficiency. Field studies were conducted in Texas to determine the effect of harvest aids (glyphosate, diquat-dibromide, glufosinate-ammonium, and carfentrazone-ethyl) on sesame drydown and yield. The objective was to identify one or more harvest aids that could (1) accelerate drydown, (2) burn-down green weeds, (3) even up a field with varying levels of drydown, (4) stop regrowth, (5) stop vivipary, and (6) prepare to plant a new crop. Other than diquat-dibromide, the herbicides were chosen based on the effect on weeds in other crops. The plan was to apply the herbicides 1 week before physiological maturity (PM), at PM, and 1 week after PM. However, sesame maturity is very sensitive to ground moisture, ambient temperature, and relative humidity. The weather was different in all trials and some stages could not be completed. In two cases, the trials had to be abandoned; however, certain patterns emerged. All the herbicides accelerated drydown compared to the untreated check. Diquat-dibromide and glufosinate-ammonium dried sesame faster than glyphosate and carfentrazone-ethyl. The higher rates of the herbicide dried down the sesame faster than the low rate. Although there were some differences in yields across the three application periods, there was no consistent pattern.