Field studies were conducted in Louisiana and Mississippi in 2009 and 2010 to evaluate PRE herbicide treatments containing isoxaflutole or a prepackaged mixture of thiencarbazone-methyl : isoxaflutole (TCM : isoxaflutole) for weed control in corn. PRE treatments included the premix of TCM : isoxaflutole alone (30 : 80 g ai ha−1) and with atrazine (1,120 g ai ha−1), isoxaflutole alone (90 g ai ha−1) and with atrazine (1,120 g ai ha−1), and the premix of atrazine plus S-metolachlor (1,820 plus 1,410 g ai ha−1). POST treatments included glufosinate (450 g ai ha−1) or glyphosate (870 g ae ha−1) applied to 30-cm corn along with a no POST treatment. All PRE treatments controlled barnyardgrass, entireleaf morningglory, rhizomatous johnsongrass, Palmer amaranth, and velvetleaf 87 to 95% 4 wk after planting (WAP) and browntop millet and hophornbeam copperleaf were controlled 86 to 95% 8 WAP. Weed control was improved 8 and 20 WAP when either POST treatment was applied. TCM : isoxaflutole plus atrazine controlled barnyardgrass, entireleaf morningglory, Palmer amaranth, and velvetleaf at least 90% 20 WAP regardless of POST treatment. TCM : isoxaflutole plus atrazine provided greater control of browntop millet (90%) than isoxaflutole alone or with atrazine and atrazine plus S-metolachlor where control was 86% 20 WAP. Pooled across POST treatments, all PRE treatments containing isoxaflutole or TCM : isoxaflutole controlled rhizomatous johnsongrass better (74 to 76%) than atrazine plus S-metolachlor (67%). Corn yield following herbicide treatments ranged from 9,280 to 11,040 kg ha−1 compared with 9,110 kg ha−1 for the nontreated. Results indicate that TCM : isoxaflutole or isoxaflutole PRE is an option for use in a corn weed management program and may prolong the use of atrazine where weed resistance may be an issue. Where rhizomatous johnsongrass is a problem, TCM : isoxaflutole or isoxaflutole PRE can provide better control than atrazine plus S-metolachlor PRE. Without PRE treatments, glufosinate or glyphosate was needed for season-long weed control.

In the southeastern United States many farmers double-crop winter wheat with soybean or cotton. However, there is little information about residual injury of herbicides used in wheat to these rotational crops. Experiments were conducted from 2007 to 2008 and 2008 to 2009 in soft red winter wheat to evaluate response of rotational crops of soybean and cotton after application of various acetolactate synthase herbicides in wheat. Pyroxsulam, mesosulfuron, sulfosulfuron, propoxycarbazone, or chlorsulfuron plus metsulfuron at multiple rates were applied to wheat approximately 110 to 120 d before planting rotational crops. Soils were Tift loamy sand at Ty Ty, GA and Faceville sandy loam at Plains, GA. After wheat harvest, soybean (‘Pioneer 97M50’) and cotton (‘DP 0949 B2RF’) were strip-tillage planted and evaluated for injury, stand density, height over time, and yields. For both locations, wheat was tolerant to all herbicide treatments with little to no visible injury 7 to 90 d after application. Pyroxsulam injury was less than sulfosulfuron or mesosulfuron. At recommended use rates, wheat injury was transient with no effect on yield. Double-crop soybean for both locations had no differences in stand establishment for any herbicide treatments. There was significant carryover injury to soybean and cotton for sulfosulfuron applied to wheat for the Faceville sandy loam. There was no effect of herbicide treatment on cotton stand. There was little to no difference in residual activity on rotational crops between pyroxsulam and other wheat herbicides when labeled rates were applied. This is significant as pyroxsulam is used to control Italian ryegrass and wild radish in this region.

Glyphosate-resistant (GR) giant ragweed has been confirmed in Ontario, Canada. Giant ragweed is an extremely competitive weed and lack of control in soybean will lead to significant yield losses. Seed companies have developed new herbicide-resistant (HR) crop cultivars and hybrids that stack multiple HR traits. The objective of this research was to evaluate the efficacy of glyphosate and glyphosate plus dicamba tank mixes for the control of GR giant ragweed under Ontario environmental conditions in dicamba-tolerant (DT) soybean. Three field trials were established over a 2-yr period (2010 and 2011) on farms near Windsor and Belle River, ON. Treatments included glyphosate (900 g ae ha−1), dicamba (300 g ae ha−1), and dicamba (600 g ha−1) applied preplant (PP), POST, or sequentially in various combinations. Glyphosate applied PP, POST, or sequentially provided 22 to 68%, 40 to 47%, and 59 to 95% control of GR giant ragweed and reduced shoot dry weight 26 to 80%, 16 to 50%, and 72 to 98%, respectively. Glyphosate plus dicamba applied PP followed by glyphosate plus dicamba applied POST consistently provided 100% control of GR giant ragweed. DT soybean yield correlated with GR giant ragweed control. This is the first report in Canada of weed control in DT soybean, specifically for the control of GR giant ragweed. Results indicate that the use of dicamba in DT soybean will provide an effective option for the control of GR giant ragweed in Ontario.

With the forthcoming release of the 2,4-D- and dicamba-resistance traits stacked with either glyphosate or glufosinate resistance, the use of 2,4-D or dicamba alone or in tank mix with glyphosate or glufosinate likely will increase the control of glyphosate-resistant weeds in soybean. There also is an increasing trend among soybean growers to apply POST herbicides in combination with fungicides, insecticides, and fertilizers to reduce trips over the field. Greenhouse experiments were conducted during 2011 and 2012 to evaluate glyphosate or glufosinate applications with growth regulator herbicides and other agrochemicals for the control of glyphosate-resistant horseweed and glyphosate-resistant common lambsquarters. In most cases, glyphosate or glufosinate application with 2,4-D or dicamba provided 80% or more control of glyphosate-resistant horseweed and glyphosate-resistant common lambsquarters. These studies demonstrate that performance of glufosinate alone and with agrochemicals was poor on glyphosate-resistant common lambsquarters. However, no differences in glyphosate-resistant common lambsquarters biomass were noted among treatments including glufosinate alone, glufosinate plus growth regulator herbicides, and glufosinate plus growth regulator herbicides plus agrochemicals. The agrochemicals lambda-cyhalothrin, manganese, and pyraclostrobin did not affect weed control by glyphosate or glufosinate combinations with growth regulator herbicides. Visible soybean injury was noted at 1 wk after treatment (WAT) only when glufosinate was applied with lambda-cyhalothrin or pyraclostrobin but no differences in visible injury were seen with these combinations at 3 WAT.

Recent shifts in the peanut cultivars commercially grown have led to a renewed interest in the tolerance of these new cultivars to herbicides. Field experiments were conducted in Georgia from 2008 to 2011 to evaluate the effects of chlorimuron on the incidence of tomato spotted wilt virus (TSWV) and yield of ‘Florida-07’, ‘Georgia-06G’, and ‘Tifguard’. Chlorimuron at 9 g ai ha−1 was applied at 60 to 69, 70 to 79, 90 to 99, and 100 to 109 d after peanut emergence (DAE). TSWV was increased by only 3% when chlorimuron was applied to Tifguard at 60 to 69 DAE. Yields of Florida-07 were not influenced by any timing of chlorimuron. Chlorimuron applied 60 to 69, 70 to 79, and 90 to 99 DAE caused yield reductions when applied to Georgia-06G. Yields of the cultivar Tifguard were reduced when chlorimuron was applied 70 to 79, 90 to 99, and 100 to 109 DAE. Yield losses from chlorimuron ranged from 7 to 11%.

Studies were conducted in Oklahoma and Arkansas to evaluate the tolerance of nine advanced cowpea breeding lines and one cultivar treated PRE with halosulfuron at 1× (0.054 kg ha−1) and 2× (0.107 kg ha−1) rates. The breeding lines, developed by the University of Arkansas, included 01-103, 01-111, 01-117, 01-140, 01-174, 01-180, 01-181, 01-184, and 01-198. ‘Early Scarlet’ was also included as the standard commercial cultivar. Halosulfuron did not reduce the emergence of the breeding lines and Early Scarlet in Oklahoma, but reduced cowpea emergence 14% at the 2× rate in Arkansas. All breeding lines and Early Scarlet had similar emergence capacity in both locations. Higher injury (crop stunting, up to 59% at the 2× rate) and reduction in flowering (up to 83% points at the 1× rate) were observed in Arkansas, but not in Oklahoma. Averaged over herbicide rate, yield was higher and did not differ among cultivars in Arkansas (0.89 to 1.18 Mg ha−1) versus Oklahoma (0.36 to 0.82 Mg ha−1). The highest yield in Oklahoma was obtained from 01-174, 01-103, and 01-117. Despite the observed phytotoxicity symptoms, halosulfuron did not reduce cowpea yield. Halosulfuron is safe to use with these breeding lines and cultivar, at the 0.054 kg ha−1 rate, but may delay cowpea maturity almost 1 wk in soils of close to neutral pH or higher.

Field studies were conducted to evaluate Italian ryegrass control and winter wheat tolerance to applications of diclofop, mesosulfuron plus methylated seed oil (MSO) alone or with 30% urea ammonium nitrate (UAN), mesosulfuron plus thifensulfuron plus tribenuron plus MSO, mesosulfuron plus MCPA plus MSO, or flufenacet plus metribuzin. Treatments were applied to wheat PRE, two- to three-leaf wheat (2–3 LF) at Feekes stage 1.0 or to one- to two-tiller wheat (TILL) at Feekes stage 3.0, depending on label recommendations. Studies were conducted in Williamson, GA, and Plains, GA, from autumn 2003 to spring 2005. Italian ryegrass control was variable, depending on location and year. Maximum and most-consistent Italian ryegrass control (> 90%) occurred with mesosulfuron plus MSO and UAN. Without UAN, control of Italian ryegrass with mesosulfuron varied from 44 to 97%. That variability was partially attributed to unfavorable environmental conditions associated with cold night time temperatures at or below 0 C, following applications. Wheat injury observed in response to herbicide treatments was minimal (< 15%) and transient; wheat recovered with no differences in yield.

Yellow nutsedge is an important weed problem in furrow-irrigated fields in the Treasure Valley of eastern Oregon and southwestern Idaho. Field studies were conducted in 2008 and 2009 to evaluate the effect of PPI S-metolachlor or EPTC followed by POST halosulfuron and dicamba plus glyphosate or glyphosate alone on foliar yellow nutsedge control and tuber production in corn. Corn plant height at 8 and 24 d after treatment (DAT) was reduced 20 and 17%, respectively, in POST herbicides alone compared with PPI plus POST herbicide treatments. Yellow nutsedge control at 8 DAT averaged 78% for treatments that included PPI application of EPTC or S-metolachlor 1,600 g ai ha−1 followed by halosulfuron plus dicamba (35 plus 155 g ha−1 or 70 plus 310 g ha−1) plus glyphosate 785 g ha−1 compared with POST treatments alone (49%). The control at 24 DAT was 84% for treatments that contained halosulfuron plus dicamba compared with 73% for POST glyphosate alone. Yellow nutsedge tubers were reduced 56 to 68% among treatments at the end of 2008. Tuber reduction in 2009 was greater with treatments that included PPI herbicides followed by sequential halosulfuron plus dicamba (35 plus 155 g ha−1) plus glyphosate compared with glyphosate alone. Corn yield reflected the level of yellow nutsedge control and early-season weed interference. Treatments that included PPI herbicides had an average yield of 8.2 T ha−1 compared with 6.6 T ha−1 with sequential glyphosate alone. There was a correlation between percent foliar control and the number of yellow nutsedge tubers produced at the end of each year. Application of PPI herbicides followed by POST halosulfuron plus dicamba (35 plus 155 g ha−1 or 70 plus 155 g ha−1) plus glyphosate improved yellow nutsedge control, reduced early corn–weed competition, and produced the highest corn yield under furrow-irrigated conditions.

Inadequate corn stands due to extreme weather conditions may require producers to replant their corn fields. The use of GR corn, however, can result in difficulty in managing replanted corn without experiencing yield loss. Therefore, the objectives of this research were to evaluate the herbicide options for control of GR corn in a corn replant situation and to determine the effect of corn replanted into various initial corn stands on grain yield. Two field studies were conducted to accomplish the objectives. The first experiment was designed to identify the most efficacious herbicide treatment for GR corn removal in a corn replant situation. Clethodim (51 g ai ha−1) applied 6 d prior to replanting, paraquat (700 g ai ha−1) plus metribuzin (160 g ai ha−1) applied at replanting, and glufosinate (450 g ai ha−1) applied at replanting along with a sequential treatment 3 wk later provided 96 to 100% control of the initial corn stand and resulted in the highest yield. If corn from the first planting remains, the interaction between different sized plants can reduce yield of corn. Thus, a second field experiment was conducted to evaluate the influence on grain yield of corn replanted into various initial corn stands. Corn stands of 0, 20,000, 40,000, 60,000, 80,000, and 100,000 plants ha−1 were established and either followed by a corn replant at 80,000 seeds ha−1 or not replanted. Initial stands ≥ 60,000 plants ha−1 did not require a replant to maximize yield. Initial corn stands ≤ 40,000 plants ha−1 required a replant with initial stand control to maximize grain yield. The percent yield contribution from an initial stand of 20,000 plants ha−1 was 20% greater than the same population replanted a few weeks later, which showed the competitive advantage to earlier planting even at the lowest initial corn stand. Because of this competitive advantage, an initial stand must be removed to maximize corn yield in a replant situation.

Indaziflam controls annual grassy weeds by inhibiting cellulose biosynthesis. Research was conducted from 2008 to 2011 in Tennessee, Texas, and Georgia evaluating the efficacy of indaziflam for PRE and POST control of annual bluegrass in bermudagrass turf. In Texas, indaziflam at 30, 40, 50, and 60 g ai ha−1 applied PRE provided 93 to 100% annual bluegrass control through 28 wk after treatment. When applied PRE at 80 g ai ha−1 and at 4, 8, and 12 wk after PRE (WAP), indaziflam controlled annual bluegrass 67 to 100% 32 wk after initial treatment (WAIT) in Tennessee; however, reduced efficacy was observed with 12 WAP treatments in a single year of a 2-yr study. Similarly, annual bluegrass control with PRE applications or with 4 and 8 WAP applications of indaziflam at 35 and 52.5 g ai ha−1 ranged from 88 to 100% at 30 WAIT in Tennessee. In Georgia, these rates of indaziflam applied PRE and 4 WAP controlled annual bluegrass 96 to 100% on all evaluation dates and resulted in 97 to 100% reduction in plant counts relative to the untreated control at 30 WAIT. When applied 8 WAP, the 35 and 52.5 g ai ha−1 rates of indaziflam controlled annual bluegrass only 51 to 71% at 30 WAIT in Georgia. Although increasing the application rate of indaziflam treatments 8 WAP provided greater annual bluegrass control, each rate provided significantly lower control when applied 8 WAP compared with PRE or at 4 WAP. No bermudagrass injury was observed in this research. Results suggest indaziflam provides effective PRE and early POST control of annual bluegrass in bermudagrass turf. However, additional research is needed to determine the effects of plant size and maturity on indaziflam efficacy for POST annual bluegrass control.

At the field scale, weeds generally appear aggregated rather than randomly distributed, and this aggregation is linked to the spatial heterogeneity of biotic and abiotic factors. Crop management practices shape the spatial pattern of weed infestations by modifying certain factors having an impact on weed emergence and growth. Although crop seeding is often the last in-field disturbance before crop and weed emergence, its effect on the distribution of weeds has received little attention in the literature. The purpose of this study was to assess the influence of the planting operation on weed cover and presence in corn fields using digital images to investigate the possibility of sensing the interrow to infer the presence or absence of weeds on the corn row. A total of 18 site-years under conventional tillage treated with a single POST application of herbicide were selected across seven locations. Image analysis, at the V2 to V4 growth stage of corn, was used to compare the weed cover in three zones: the undisturbed interrows, the corn rows, and the interrows compacted by tractor wheel traffic. For 61% of site-years, there was no significant difference among the zones. When there was a significant difference compared with the other two zones, the undisturbed interrow was usually less infested. Point-to-point comparisons of weed presence or absence (based on a threshold of five pixels) between the interrow and the corn row revealed 70 or 73% correspondence, depending on the type of interrow (undisturbed or tracked). However the error of inference of the corn row weed cover generated by sensing only adjacent interrows may be too high for efficient commercial weed control.

Field studies were conducted in central Missouri and central Kansas to evaluate the crop tolerance and efficacy of various combinations of atrazine, flufenacet + isoxaflutole, flumetsulam + clopyralid, isoxaflutole, and S-metolachlor applied PPI or PRE in conventional-till corn. Application technique did not influence crop injury in Kansas. In Missouri, greater crop injury was observed with treatments containing isoxaflutole when applied PPI vs. PRE. Application technique influenced giant foxtail, ivyleaf morningglory, large crabgrass, Palmer amaranth, and common waterhemp control. In dry years, control of these weeds was usually either same or greater with PPI than it was with PRE treatments. In years with average to above average precipitation, isoxaflutole provided greater control as a PRE application than as a PPI application. Palmer amaranth and common waterhemp control was usually greater with atrazine, isoxaflutole, and S-metolachlor applied PRE than it was applied PPI. Differences in control of all weeds between PPI and PRE applications were less obvious with two or three herbicides compared with treatments with a single herbicide. In general, the corn yield was greater with most of the treatments having two, three, or four herbicides than it was with treatments having a single herbicide, which was due to better weed control with the tank-mixtreatments.

The continued phase-out of methyl bromide (MBr) challenges vegetable growers' abilities to control weeds in plasticulture production. Herbicides, such as EPTC (S-ethyl dipropylthiocarbamate), may be needed as part of a MBr alternative system. An experiment was conducted during the springs of 2008 and 2009 in Ty Ty, GA, to determine tomato, pepper, eggplant, and watermelon tolerance to EPTC applied under mulch. Treatments consisted of a factorial arrangement of four rates of EPTC (0, 2, 3, or 4 kg ai ha−1) and two plastic mulch types (low density polyethylene [LDPE] mulch or a high barrier mulch [HBM]). Each crop was planted 28 d after applying herbicides and laying mulch. EPTC, regardless of rate, applied under LDPE mulch did not impact plant growth, fruit number produced, or fruit weights for any crop. Conversely, pepper, tomato, and eggplant heights were reduced 65 to 72%, 30 to 75%, and 9 to 32%, respectively, by EPTC at 2 to 4 kg ai ha−1 when applied under HBM. Similar trends were observed for crop yield; fruit number and weight were reduced by 71 to 84% for pepper, 36 to 76% for tomato, and 7 to 15% for eggplant when EPTC was applied at 2 to 4 kg ai ha−1 as compared to the no EPTC HBM control. Watermelon stem lengths, fruit number, and fruit weights were not impacted by EPTC applied under HBM mulch. It appears as though HBMs reduce the loss of EPTC through volatilization, thereby increasing the dose present at time of planting. EPTC could be included as part of a MBr alternative system for tomato, pepper, eggplant, and watermelon when applied under LDPE mulch, and may also be applied at labeled rates with the HBM utilized in this experiment for watermelon.

The introduction of 2,4-D-resistant crops stacked with glyphosate resistance will enable the use of 2,4-D and glyphosate for weed control in corn, cotton, and soybean. Because there is little reported on the effectiveness of 2,4-D plus glyphosate on summer annual weed control, the objective was to evaluate 2,4-D and glyphosate tank mixtures on summer annual weed control. Six rates of 2,4-D (0, 280, 420, 560, 840, and 1,120 g ae ha−1) and three rates of glyphosate (0, 840, and 1,120 g ae ha−1) were applied to common lambsquarters, common waterhemp, giant ragweed, giant foxtail, and velvetleaf. Glyphosate at 840 g ha−1 controlled all weeds 94 to 100%. Giant ragweed was controlled 99 to 100% by 2,4-D alone when rates were 280 g ha−1 or higher. Common lambsquarters, common waterhemp, and velvetleaf control increased as 2,4-D rates increased, with 1,120 g ha−1 providing 90 to 94% control.

Management of Italian ryegrass in cereal-based cropping systems continues to be a major production constraint in areas of the United States, including the soft white winter wheat producing regions of the Pacific Northwest. Pyroxasulfone is a soil-applied herbicide with the potential to control broadleaf and grass weed species, including grass weed biotypes resistant to group 1, 2, and 7 herbicides, in several crops for which registration has been completed or is pending, including wheat, corn, sunflower, dry bean, and soybean. Field experiments were conducted from 2006 through 2009 near Corvallis, OR, to evaluate the potential for Italian ryegrass control in winter wheat with applications of pyroxasulfone. Application rates of PRE treatments ranged from 0.05 to 0.15 kg ai ha−1. All treatments were compared to standard Italian ryegrass soil-applied herbicides used in winter wheat, including diuron, flufenacet, and flufenacet + metribuzin. Visual evaluations of Italian ryegrass and ivyleaf speedwell control and winter wheat injury were made at regular intervals following applications. Winter wheat yields were quantified at grain maturity. Ivyleaf speedwell control was variable, and Italian ryegrass control following pyroxasulfone applications ranged from 65 to 100% and was equal to control achieved with flufenacet and flufenacet + metribuzin treatments and greater than that achieved with diuron applications. Winter wheat injury from pyroxasulfone ranged from 0 to 8% and was most associated with the 0.15–kg ha−1 application rate. However, this early-season injury did not negatively impact winter wheat yield. Pyroxasulfone applied at the application rates and timings in these studies resulted in high levels of activity on Italian ryegrass and excellent winter wheat safety. Based on the results, pyroxasulfone has the potential to be used as a soil-applied herbicide in winter wheat for Italian ryegrass management and its utility for management of other important grass and broadleaf weeds of cereal-based cropping systems should be evaluated.

Dry pea improves corn yield and tolerance to weed interference compared with soybean, spring wheat, or canola as preceding crops. To understand this synergy between dry pea and corn, growth and nutrient concentration of corn were examined following dry pea or soybean in sequence. Each corn plot was split into weed-free and weed-infested subplots, with foxtail millet established at one density to provide uniform weed interference. Compared with soybean, dry pea improved corn grain yield 10% in weed-free conditions and corn tolerance to weed interference more than twofold. Dry pea synergy to corn in weed-free conditions was not related to differences in corn development, height, or nutrient status of corn seedlings. When foxtail millet was present, dry pea increased corn height and rate of development late in the growing season compared with soybean. Improved corn tolerance to weed interference was not related to seedling emergence or growth of foxtail millet, as these parameters did not vary with preceding crop. Other biological factors must be involved in dry pea synergy to corn.

Field and greenhouse studies were conducted in Belle Glade, FL, in 2010 and 2011 to evaluate saflufenacil and glyphosate efficacy on POST burndown of ragweed parthenium. Log-logistic models were used to determine the herbicide dose required to produce 90% control (ED90). The ED90 for rosette ragweed parthenium control in the greenhouse was saflufenacil at 8.0 g ai ha−1 at 14 d after treatment. The rate required to cause 90% growth reduction of rosette ragweed parthenium at 14 d after treatment was 8.9 g ha−1 of saflufenacil. The probability of rosette ragweed parthenium survival decreased with increasing rates of saflufenacil. The ED90 value for bolted ragweed parthenium control in the field was 5.7 g ha−1 of saflufenacil at 21 d after treatment. Ragweed parthenium had no response to glyphosate either in the field or in the greenhouse studies. This demonstrates that saflufenacil can be used as a POST burndown of ragweed parthenium populations that have no response to glyphosate.

Experiments were conducted during 2007 and 2008 to evaluate various herbicide treatment regimes for POST purple nutsedge and false-green kyllinga control. Evaluated herbicides included halosulfuron, sulfentrazone, sulfosulfuron, and trifloxysulfuron. Evaluated treatments did not cause objectionable bermudagrass injury at any time. Results were variable across years, likely due to reduced rainfall in 2007 causing reduced purple nutsedge and false-green kyllinga growth. In 2007, averaged across herbicide rate and number of applications, sulfosulfuron provided greater purple nutsedge control than trifloxysulfuron. Sulfosulfuron and trifloxysulfuron provided similar levels of control in 2008, although both were less effective than in 2007. In 2007, sulfosulfuron and trifloxysulfuron provided excellent (> 90%) false-green kyllinga control, and trifloxysulfuron provided greater control (80%) compared to sulfosulfuron (61%) in 2008. Sulfentrazone provided < 30 and 60% purple nutsedge and false-green kyllinga control, respectively. A sequential application applied 6 wk after initial treatment provided the highest level of purple nutsedge and false-green kyllinga control with evaluated herbicides. Tank-mix partners to enhance purple nutsedge control with sulfentrazone provided inconsistent results. Sulfosulfuron and trifloxysulfuron offer acceptable POST perennial sedge control in tolerant warm-season turfgrasses.

Field studies were conducted near Crowley, LA, in 2005 through 2007 to evaluate the effects of simulated herbicide drift on ‘Cocodrie’ rice. Each application was made with the spray volume varying proportionally to herbicide dosage based on a constant spray volume of 234 L ha−1 and an imazethapyr rate of 70 g ai ha−1. The 6.3%, 4.4 g ha−1, herbicide rate was applied at a spray volume of 15 L ha−1 and the 12.5%, 8.7 g ha−1, herbicide rate was applied at a spray volume of 29 L ha−1. An application of imazethapyr at one-tiller, panicle differentiation (PD), and boot resulted in increased crop injury compared with the nontreated rice. The most injury observed occurred on rice treated at the one-tiller timing. Imazethapyr at one-tiller, PD, and boot reduced plant height at harvest and primary and total (primary plus ratoon) crop yield, with the greatest reduction in primary crop yield resulting from imazethapyr applied at boot. Imazethapyr did not affect rice treated at primary crop maturity.

Greenhouse experiments were conducted to determine the effects of herbicide placement on POST smooth crabgrass and annual bluegrass control. Soil-plus-foliar, soil-only, and foliar-only applications of indaziflam (52.5 g ai ha−1), dithiopyr (560 ai g ha−1), or quinclorac (840 g ai ha−1) were made to one-tiller smooth crabgrass plants. Similarly, indaziflam (52.5 g ha−1), foramsulfuron (29 g ai ha−1), or prodiamine (840 g ai ha−1) were applied to nontillering annual bluegrass plants in an identical manner. No differences in smooth crabgrass control were detected between soil-plus-foliar and soil-only applied indaziflam from 21 to 35 d after treatment (DAT). By 28 DAT, smooth crabgrass control and biomass reductions with these indaziflam treatments were ≥ 90% and not different than quinclorac. Comparatively, smooth crabgrass control with foliar-only applications of indaziflam never exceeded 28%. Responses on annual bluegrass were similar as soil-plus-foliar and soil-only applied indaziflam exhibited greater efficacy than indaziflam applied foliar-only. By 28 DAT, annual bluegrass control and aboveground biomass reductions with soil-plus-foliar and soil-only treatments were ≥ 86% and not different from foramsulfuron. Comparatively, foliar-only applications of indaziflam controlled annual bluegrass ≤ 2%. These results indicate that root absorption is required for POST control of smooth crabgrass and annual bluegrass with indaziflam. Further research is needed to determine if techniques to enhance indaziflam contact with soil will enhance POST smooth crabgrass and annual bluegrass control in the field.