Chicory (Cichorium intybus L. # CICIN), succory, blueweed, coffee-weed, blue sailors, bunk, or blue daisy, is familiar to many of us as an erect weed along roadsides or in fields, displaying small, startlingly bright blue flowers. Others of us may only have tasted its roots—roasted and ground into a bittersweet coffee substitute or additive: an essential component of the New Orleans brew served blacker than a hundred midnights in a cypress swamp. Along with its close relative endive (Cichorium endivia L.), chicory also has an important place in the salads of Europe and, increasingly, the United States. Both chicory and endive were indispensable in ancient and medieval herbal pharmacies and are still used medicinally today.

EPTC applied at the time of ‘Saranac AR’ alfalfa establishment resulted in higher levels of crop injury from the octanoic acid ester of bromoxynil applied postemergence compared to alfalfa in areas not treated with EPTC. EPTC applied at 1.7 or 3.4 kg ai ha-1 did not injure alfalfa. At Rock Springs, PA, 0.54 kg ai ha-1 bromoxynil caused 28, 43, and 55% foliar injury in areas treated with 0, 1.7, and 3.4 kg ai ha-1 EPTC, respectively. A similar interaction was observed at Landisville, PA, although the level of injury due to bromoxynil was less severe. EPTC also predisposed ‘WL 316’ alfalfa to bromoxynil injury in greenhouse experiments.

Fourteen field experiments were conducted from 1988 to 1991 in Oklahoma to evaluate herbicides for red horned poppy control in winter wheat. Chlorsulfuron applied alone PRE at 9 to 26 g ai ha-1 or with metsulfuron controlled red horned poppy 90 to 100% in four of five locations. MCPA at 420 g ae ha-1 and MCPA + bromoxynil at 140 + 140 g ae ha-1 applied POST in mid November controlled red horned poppy 100%. All herbicides applied POST in mid March failed to control the weed consistently.

Hair fescue is a common perennial grass that reduces yields in lowbush blueberry fields. This grass is suppressed with nonbearing-year foramsulfuron applications, though suppression may be improved through use of sequential glufosinate and foramsulfuron applications. The objective of this research was to determine the main and interactive effects of fall bearing-year glufosinate applications, spring nonbearing-year glufosinate applications, and spring nonbearing-year foramsulfuron applications on hair fescue. The experiment was a 2 by 2 by 2 factorial arrangement of fall bearing-year glufosinate application (0, 750 g ai ha–1), spring nonbearing-year glufosinate application (0, 750 g ai ha–1), and spring nonbearing-year foramsulfuron application (0, 35 g ai ha–1) arranged in a randomized complete block design at lowbush blueberry fields located in Parrsboro and Portapique, NS, Canada. Fall bearing-year glufosinate applications, spring nonbearing-year glufosinate applications, and spring nonbearing-year foramsulfuron applications alone provided inconsistent hair fescue suppression. Fall bearing-year glufosinate applications followed by spring nonbearing-year foramsulfuron applications, however, reduced nonbearing-year total tuft density, flowering-tuft density, and flowering-tuft inflorescence number at each site and reduced seed production at Portapique. Sequential fall bearing-year and spring nonbearing-year glufosinate applications or sequential spring nonbearing-year glufosinate and foramsulfuron applications reduced flowering-tuft density and flowering-tuft inflorescence number at each site but did not consistently reduce total tuft density. Sequential herbicide treatments reduced bearing-year seedling density and may therefore contribute to hair fescue seed bank management in lowbush blueberry.

Genetic similarities between johnsongrass and grain sorghum leave producers with limited herbicide options for postemergence johnsongrass control. TamArkTM grain sorghum with resistance to acetyl-CoA carboxylase-inhibiting herbicides was developed through a collaboration between the University of Arkansas System Division of Agriculture and Texas A&M AgriLife Research. Two field experiments were conducted in 2021 in two locations each: Keiser and Marianna, AR, or Fayetteville and Marianna, AR. The objective of the first was to determine the optimal rate and application timing of fluazifop-butyl for control of natural johnsongrass populations in a noncrop setting, and the objective of the second was to evaluate johnsongrass control and TamArkTM grain sorghum tolerance in response to fluazifop-butyl applied at different timings and rates based on crop growth stage. The highest levels of johnsongrass control occurred when sequential applications of fluazifop-butyl were utilized. All sequential treatments provided at least 80% johnsongrass control at any rate or application timing tested. A single application of fluazifop-butyl provided greater than 90% johnsongrass control when applied at 210 g ai ha−1 to johnsongrass with fewer than 6 leaves. Weed size played a role in achieving high levels of johnsongrass control. Greater than 90% control was achieved when johnsongrass had 6 leaves or fewer at the initial application for the sequential application treatments. A single application of fluazifop-butyl at 105 g ai ha−1 resulted in no more than 82% johnsongrass mortality at any application timing. TamArk™ grain sorghum injury did not exceed 6% at any application timing or rate. It was therefore considered to be safe even if the initial application was made before the 6-leaf crop stage. Because no unacceptable levels of injury were observed with TamArk™ grain sorghum for fluazifop-butyl, johnsongrass size at the time of application should be the most critical aspect for control with this herbicide.

Environmental conditions surrounding herbicide applications are known to affect weed control and crop response. Variable levels of rice injury caused by florpyrauxifen-benzyl have been observed across cropping systems and environmental conditions, warranting research in which single environmental and management strategies are isolated to understand the effect of each factor on rice injury and subsequent reductions in rice growth. A field study was conducted to determine the effects of planting date, rice cultivar, and florpyrauxifen-benzyl rate on rice injury, maturity, and yield. Two greenhouse studies were conducted to determine the effect of soil moisture and time of flooding after florpyrauxifen-benzyl application on rice injury caused by the herbicide. Growth chamber experiments were conducted to isolate the effects of temperature and light intensity on rice injury caused by florpyrauxifen-benzyl. In the field study, levels of injury varied across planting dates in both years, indicating the influence of environment on the crop response to florpyrauxifen-benzyl applications. Under dry (40% soil moisture) and saturated (100%) soil conditions, rice injury increased to 36% and 35%, respectively, compared with 27% and 25% injury at 60% and 80% soil moisture, respectively. Flooding rice 0 to 6 d after florpyrauxifen-benzyl application reduced visible injury; however, a reduction in rice tiller production occurred when the rice was flooded the same day as application. Visible rice injury increased when florpyrauxifen-benzyl was applied under low light intensity (700 µmol m−2 s−1) and high temperatures (35/24 C day/night). Based on these findings, applications of florpyrauxifen-benzyl are least likely to cause unacceptable rice injury when applied to soils having 60% and 80% saturation in high light, low temperature environments, and the crop is flooded 3 to 6 d following application.

The effect of various growth regulators on seedling field bindweed (Convolvulus arvensis L. # CONAR) growth and control with herbicides was evaluated. Fourteen growth regulators were applied at 0.38 to 380 g/ha 7 days before herbicide application in greenhouse, growth chamber and field studies. Field bindweed seedlings pretreated with growth regulators were more effectively controlled by herbicides compared to those not pretreated in greenhouse evaluations. Abscisic acid [[R-(Z,E)]-(+)-5-(1-hydroxy-2,6-6-trimethyl-4-oxo-2-cyclohexane-1-yl)-3-methyl-2,4-pentadicenoic acid] (ABA), ancymidol [a-cyclopropyl-a-(p-methoxyphenyl)-5-pyrimidine methanol], cycloheximide {3-[2-(3,5-dimethyl-2-oxocylohexyl)-2-hydroxyethyl]glutarimide}, ethylenediamine tetraacetic acid [N,N′-1,2-ethanediyl-bis-(N-(carboxymethyl) glycine] (EDTA), and 1-naphthaleneacetic acid (NAA) increased field bindweed stem length. Ancymidol and gibberellic acid [ent-3α,10,13-trihydroxy-20-norgibberell-1,16-diene-7,19-dioc acid 19,10-lactone] (GA) increased root weight, and GA increased root length. Cycloheximide, ethephon [(2-chloroethyl)phosphonic acid] and MH (1,2-dihydro-3,6-pyridazinedione) decreased field bindweed root weight. Ancymidol, GA and IAA (indole-3-acetic acid) increased the number of shoots per plant of seedling field bindweed. Dicamba (3,6-dichloro-2-methoxybenzoic acid) efficacy was enhanced following field bindweed preconditioning with ethephon and IAA. Ancymidol and cycloheximide applied as pretreatments increased glyphosate [N-(phosphonomethyl)glycine] activity on seedling field bindweed. Ancymidol and IAA pretreatment improved field bindweed control with triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}. Herbicide-growth regulator combination treatments that increased field bindweed control in greenhouse and growth chamber studies did not increase top growth control in the field.

Herbicide resistance in Palmer amaranth and waterhemp is on the rise and poses a great concern to growers in the United States. A multistate screening was conducted for these two weed species in the United States to assess their sensitivity to glufosinate, dicamba, and 2,4-D. The screening was designed to understand the weed sensitivity landscape and emerging trends in resistance evolution by testing each herbicide at its respective label rate and at half the label rate. A total of 303 weed seed accessions from 21 states representing 162 Palmer amaranth and 141 waterhemp seeds were collected from grower fields in 2019 and screened in greenhouse conditions. Statistical power of different sample sizes and probability of survivors in each accession were estimated for each species and herbicide treatment. Overall, the efficacy of glufosinate, dicamba, and 2,4-D against all these accessions was excellent, with greater than 90% average injury. The variability in herbicide injury, if any, was greater with half the label rate of 2,4-D in some Palmer amaranth accessions, while waterhemp accessions had exhibited variable sensitivity with half the label rate of dicamba and glufosinate. The study highlights the value of monitoring weeds for herbicide sensitivity across broader landscape and the importance of glufosinate, dicamba, and 2,4-D herbicides in managing troublesome weeds as part of a diversified weed control program integrated with other chemical, mechanical and cultural practices.

Corn that is resistant to aryloxyphenoxypropionate, known commercially as Enlist™ corn, enables the use of quizalofop-p-ethyl (QPE) as a selective postemergence (POST) herbicide for control of glufosinate/glyphosate-resistant corn volunteers. Growers usually mix QPE with 2,4-D choline or glufosinate or both to achieve broad-spectrum weed control in Enlist corn. The objectives of this study were 1) to evaluate the efficacy of QPE applied alone or mixed with 2,4-D choline and/or glufosinate to control glufosinate/glyphosate-resistant corn volunteers in Enlist corn and 2) to determine the effect of application time (V3 or V6 growth stage of volunteer corn) of QPE-based treatments on volunteer corn control and Enlist corn injury and yield. Field experiments were conducted in Clay Center, NE, in 2021 and 2022. Quizalofop-p-ethyl (46 or 93 g ai ha−1) applied at the V3 or V6 growth stage controlled volunteer corn by ≥88% and ≥95% at 14 and 28 d after treatment (DAT), respectively. QPE (46 g ai ha−1) mixed with 2,4-D choline (800 g ae ha−1) produced 33% less than expected control of V3 volunteer corn in 2021, and 8% less than expected control of V6 volunteer corn in 2022 at 14 DAT. Volunteer corn control was improved by 7% to 9% using the higher rate of QPE (93 g ai ha−1) in a mixture with 2,4-D choline (1,060 g ae ha−1). QPE mixed with glufosinate had an additive effect and interactions in any combinations were additive beyond 28 DAT. Mixing 2,4-D choline can reduce QPE efficacy on glufosinate/glyphosate-resistant corn volunteers up to 14 DAT when applied at the V3 or V6 growth stage; however, the antagonistic interaction did not translate into corn yield loss. Increasing the rate of QPE (93 g ai ha−1) while mixing with 2,4-D choline can reduce antagonism.

Drill-interseeding cover crops into standing corn (V3 to V5 growth stage) provides opportunities for increasing functional diversity in cropping systems by facilitating use of cover crop mixtures that include grass, legume, and brassica species. Designing herbicide-based weed control programs that negotiate tradeoffs between crop protection and environmental goals when interseeding mixtures remains a major challenge. The objective of this study was to use greenhouse-based dose-response assays to describe the relative sensitivity of 12 cover crop species that differ in traits, including taxonomic group and seed mass, to chloroacetamide (acetochlor, dimethenamid, S-metolachlor; Group 15 herbicides as categorized by the Weed Science Society of America) and pyrazole (pyroxasulfone; Group 15) herbicides. Nonlinear models were fit, and effective doses were estimated (ED50) to compare relative sensitivities of cover crop species to each herbicide. Brassica species (winter canola, Dwarf Essex rape, daikon radish) were less sensitive than small-seeded legumes (medium red clover, crimson clover) and grasses (annual ryegrass) in response to each chloroacetamide, but similar in response to pyroxasulfone. Austrian winter pea, a large-seeded legume, was less sensitive to each herbicide compared to other legumes (crimson clover, medium red clover, hairy vetch). Cereal rye and triticale were less sensitive to dimethenamid, S-metolachlor, and pyroxasulfone compared to annual ryegrass, but similar sensitivities were observed for acetochlor. These results suggest that relative differences in sensitivity to chloroacetamide and pyrazole herbicides could be exploited when designing cover crop mixtures for interseeding. It is imperative, however, to use these findings in conjunction with field-based observations of cover crop injury potential in interseeded systems.