Herbicide resistance coupled with a dearth of selective herbicide options has increased the complexity of annual bluegrass control in hybrid bermudagrass putting greens. Cumyluron, endothall, and methiozolin are herbicides that control annual bluegrass by inhibiting novel sites of action compared with the herbicides currently used for turfgrass management in the United States. However, peer-reviewed literature contains no information on hybrid bermudagrass putting green tolerance to these herbicides. Sixteen field studies were established on eight golf greens in Midlothian, VA, in 2021 and 2022 to evaluate effects of cumyluron, endothall, methiozolin, pronamide, and trifloxysulfuron on bermudagrass spring transition. The 16 studies were split equally between initiation during full dormancy versus mid-spring transition. Methiozolin applied at 500 and 1,000 g ai ha−1 typically increased the heat units (growing degree days with a base temperature of 15 C) required for hybrid bermudagrass to visibly achieve 90% green coverage (T90) when applied to fully dormant hybrid bermudagrass. This delay in green coverage was more pronounced at sites where hybrid bermudagrass vigor was seemingly reduced via abiotic stressors. Endothall was generally more injurious than all other treatments when applied to hybrid bermudagrass during mid-transition. Endothall applied at 840 g ai ha−1 injured hybrid bermudagrass for 0 to 9 d over a threshold of 30% (DOT30), depending on location. In two site-years characterized by increased abiotic stress, methiozolin applied at 1,000 g ai ha−1 caused 44 DOT30. Cumyluron never injured hybrid bermudagrass by more than 30% or delayed T90 regardless of application timing. These results indicate that methiozolin should be applied only within labeled rates to actively growing hybrid bermudagrass putting greens, cumyluron can be safely applied at 6,450 g ai ha−1 to dormant or actively growing bermudagrass greens, and endothall applications should be limited to dormant bermudagrass greens unless transient phytotoxicity is acceptable.

Renewed interest in studying auxin herbicides (WSSA Group 4) is increasing as a result of the release of genetically engineered crop varieties that are tolerant to preemergence and postemergence applications of specific formulations of dicamba. Auxin-resistant crops were developed in response to the development of weed species resistant to glyphosate and other herbicides. Research was conducted at multiple field locations in Georgia in 2018 and 2019 to examine weed control when postemergence herbicides were applied to dicamba- and glyphosate-resistant cotton at eight different points in time over a 24-h period. Applications were made at 1 h prior to sunrise all the way up to midnight during the same day to examine the effect of herbicide application timing on broadleaf weed control. Glyphosate, dicamba, and glyphosate plus dicamba were applied at each timing. Visual ratings of weed control were scored at 7, 14, 21, and 28 d after treatment (DAT). Weed control was affected by herbicide application timing. Midnight applications resulted in the lowest levels of control. Sicklepod, pitted morningglory, and prickly sida control was 49%, 38%, and 41%, respectively. Greatest control of all three species (up to 99%) occurred from the noon to 1 h prior to sunset application timings. Orthogonal contrasts of timing of application indicated that weed control was improved with day > night and pre-dawn > midnight.

All herbicides will move off-target to sensitive crops when not applied correctly. Therefore, low-dose applications of flumioxazin and metribuzin were evaluated in soybean at the unifoliate, V2, and V4 growth stages. Rates evaluated were 12.5%, 25%, and 50% of the labeled use rates of 72 and 316 g ai ha−1 of flumioxazin and metribuzin, respectively. Flumioxazin injury was characterized by necrosis and visible height and width reduction. Injury increased with rate 3 d after treatment (DAT), with unifoliate, V2, and V4 soybean injured 15% to 30%, 18% to 27%, and 5% to 8%, respectively. Unifoliate and V4 soybean were injured more than V4 soybean 3 to 14 DAT, but injury decreased to <5% by 42 DAT. Soybean yields in the flumioxazin study were 92% to 96% of the nontreated, resulting in a yield loss of 196 to 393 kg ha−1 and a revenue loss of 71 to 141 US$ ha−1. Metribuzin injury was primarily chlorosis with necrosis and a visible reduction in soybean height and width. Soybean at the V2 growth stage was injured 14% more than V4 soybean 3 DAT, regardless of metribuzin rate. Injury to V2 and V4 soybean was similar 14 DAT, with injury of 21% to 40% across rates. Soybean injury when treated at the V2 and V4 growth stages was 6% to 29% 42 DAT compared to unifoliate soybean at 0 to 17%. Soybean yields in the metribuzin study yields were 96% to 98% of the nontreated. However, a 2% to 4% reduction equates to a loss of 90 to 180 kg ha−1 and a revenue loss of 32 to 65 US$ ha−1. Unifoliate and V2 soybean are more sensitive to a low dose of flumioxazin POST, and V2 and V4 soybean are more sensitive to a low dose of metribuzin POST. Injury and the impact on soybean growth could potentially cause economic loss for a soybean producer.

Field experiments were conducted from 2000 to 2002 at the Southern Maryland Research and Education Facility located in Upper Marlboro, MD to evaluate PPI and preemergence/prior-to-transplanting (PRE-T) applications of sulfentrazone in combination with clomazone or pendimethalin on crop injury and yield of Maryland-type tobacco. Pendimethalin was also evaluated alone. The highest levels of tobacco injury in 2000 occurred 3 wk after treatment (WAT) with PPI applications of sulfentrazone plus pendimethalin at 0.35 + 0.84 and 0.42 + 0.84 kg ai/ha, averaging 37 and 28%, respectively. In 2001, PPI applications of sulfentrazone plus clomazone at 0.42 + 0.84 kg/ha or sulfentrazone plus pendimethalin at 0.42 + 0.84 kg/ha caused 18 and 12% injury, respectively, 3 WAT. Injury in 2002 with all treatments averaged 7% or less 3 WAT. Greater rainfall through 3 WAT occurred in 2000 than in 2001 or 2002, likely contributing to the higher injury in 2000. Tobacco yields were generally similar among herbicide treatments in 2000 and 2001, and tobacco yields for all herbicide treatments were similar in 2002. The quality index was similar in 2000 and 2001, and varied slightly in 2002 among all herbicide treatments. Although a lower price was calculated for the nontreated controls, price did not vary among most herbicide treatments each year. This research shows that injury to Maryland-type tobacco can occur with sulfentrazone in combination with clomazone or pendimethalin, particularly when incorporated, and when high rainfall occurs soon after transplanting. However, injury is transient and generally has no negative influence on tobacco yield, quality, or price.

Bispyribac-sodium is an efficacious herbicide for annual bluegrass control in creeping bentgrass fairways, but turf tolerance and growth inhibition may be exacerbated by low mowing heights on putting greens. We conducted field and greenhouse experiments to investigate creeping bentgrass putting green tolerance to bispyribac-sodium. In greenhouse experiments, creeping bentgrass discoloration from bispyribac-sodium was exacerbated by reductions in mowing height from 24 to 3 mm, but mowing height did not influence clipping yields or root weight. In field experiments, discoloration of creeping bentgrass putting greens was greatest from applications of 37 g/ha every 10 d, compared to 74, 111, or 222 g/ha applied less frequently. Chelated iron effectively reduced discoloration of creeping bentgrass putting greens from bispyribac-sodium while trinexapac-ethyl inconsistently reduced these effects. Overall, creeping bentgrass putting greens appear more sensitive to bispyribac-sodium than higher mowed turf, but chelated iron and trinexapac-ethyl could reduce discoloration.

A laboratory study was conducted in 2003 at Louisiana State University in Baton Rouge, LA, to evaluate the interactive effects of bensulfuron or halosulfuron on clomazone in terms of rice foliar bleaching and chlorophyll content. Clomazone was applied alone at 0 and 1.227 μg/ml (672 g/ha) or in combination with bensulfuron at 0.0276 μg ai/ml (42 g ai/ha) or halosulfuron at 0.0345 μg ai/ml (53 g ai/ha) in a hydroponic solution. Bensulfuron and halosulfuron were also applied alone. Rice cultivars evaluated included short-grain ‘Pirogue’, medium-grain ‘Bengal’, and long-grain ‘Cocodrie’. Bensulfuron and halosulfuron, applied in a hydroponic solution, safened medium-grain Bengal, long-grain Cocodrie, and short-grain Pirogue at 21 d after treatment (DAT) from foliar bleaching caused by clomazone. Chlorophyll a and b and total chlorophyll content of all three rice cultivars decreased when treated with clomazone treatment. Only chlorophyll content of Cocodrie was increased by the addition of bensulfuron and halosulfuron compared with a single application of clomazone.

Southern Great Plains wheat growers typically apply either sulfosulfuron or propoxycarbazone-sodium for selective control of cheat. Although astute growers apply herbicides early in the growing season, herbicide application is often delayed until mid-winter or later. The effects of application timing of propoxycarbazone-sodium on cheat efficacy and on injury to the following grain sorghum crop have not been documented. Application of each herbicide at 17 intervals throughout the growing season indicated that cheat control with propoxycarbazone-sodium was greater than or equal to 90% even when application was delayed for several months after seeding. In contrast, cheat control with sulfosulfuron was variable when application was delayed more than 6 wk after wheat was seeded. Delaying sulfosulfuron application decreased wheat yield. Grain sorghum was not affected by propoxycarbazone-sodium residues regardless of application timing to wheat. Conversely, grain sorghum was severely injured by sulfosulfuron residues regardless of herbicide application timing.

The efficacy of the safeners naphthalic anhydride (NA), CGA-92194, and CGA-133205 as protectants of grain sorghum and of NA, R-29148, CGA-154281, and dichlormid as protectants of corn against injury from the chloroacetamide herbicide, SAN 582H, was evaluated under greenhouse conditions. SAN 582H applied alone reduced the shoot growth of ‘Funk G522DR’ and ‘Funk G623’ sorghum, but had no effect on the growth of the ‘GP-10’ genotype of sorghum. Corn (‘Northrup-King 9283’ hybrid) was considerably more tolerant than grain sorghum to SAN 582H. The rate of SAN 582H causing 50% reduction of corn shoot height (GR50) was 5.1 kg/ha as compared to 1.1 kg/ha for grain sorghum. NA applied as seed dressing at 5 or 10 g/kg seed, provided moderate protection to ‘G522DR’ and ‘G623’ sorghum and no protection to corn against SAN 582H injury. Dressing of sorghum seeds with CGA-133205 provided moderate protection to G522DR sorghum, whereas seed-applied CGA-92194 provided moderate protection to G623 sorghum against SAN 582H. The dichloroacetamide safeners R-29148, dichlormid, and CGA-154281 were all effective as protectants of corn against SAN 582H injury. These results demonstrate that, as with other chloroacetamide herbicides, the tolerance of corn and grain sorghum to SAN 582H can be enhanced with the use of safeners of the dichloroacetamide type and oxime ether type, respectively.

Greenhouse experiments were conducted to determine ‘Len’ hard red spring wheat response to triallate and chlorsulfuron applied separately and together. Chlorsulfuron at 12 or 23 g/ha plus preplant incorporated (PPI) triallate at 1120 g/ha antagonized triallate toxicity to wheat. Chlorsulfuron reduced triallate injury to wheat less when applied preemergence (PRE) after PPI triallate compared to both herbicides applied PPI. Soaking wheat seeds in 21 and 31 ppbw chlorsulfuron solutions for 24 h before placing into triallate-treated soil did not reduce triallate injury to wheat. Applying chlorsulfuron to triallate did not reduce triallate toxicity to wild oats.

Acifluorfen, chlorimuron, and thiameturon were compared in single and sequential treatments for cowpea control in soybean. Chlorimuron applied once at 8.8 g ai/ha at 14, 21, and 28 days after cowpea emergence controlled 80% or more of cowpea. Control was greater at 14 and 21 than at 28 days after emergence in one of three experiments. Cowpea control by chlorimuron was similar with single and sequential treatments. Soybean injury was lower, and soybean seed yields generally were higher with chlorimuron than with thiameturon or acifluorfen. Thiameturon and acifluorfen controlled less than 60% of cowpea. Three weedy cowpea cultivars responded the same to chlorimuron, but cowpea recovery was substantial in 1 of 3 yr.

Weed management in green onion continues to be a challenge for vegetable growers in Ohio. Field experiments were conducted from 2005 to 2009 to evaluate oxyfluorfen efficacy on common purslane and prostrate pigweed and green onion tolerance when applied POST at 0, 30, 70, 105, and 290 g ai ha−1 approximately 3 wk after planting. No crop injury was observed from any of the herbicide rates, except in 2009 when 209 g ha−1 oxyfluorfen resulted in 10% injury at 7 d after treatment. The transient injury did not reduce green onion yield. Green onion yield ranged from 1.8 to 2.2 kg plot−1 in 2006 and 1.3 to 1.5 kg plot−1 in 2009. In 2007 yield increased linearly from 1.9 to 3.0 kg plot−1 with oxyfluorfen rates of 0 to 105 g ha−1. Common purslane control increased as the rate of oxyfluorfen increased. Application of oxyfluorfen at 70 to 105 g ha−1 provided the best control of common purslane, ranging from 61 to 95% across the years. Similar control results were observed for prostrate pigweed. Prostrate pigweed control with 70 to 105 g ha−1 ranged from 40 to 93% from 2005 to 2009. These results suggest that green onion tolerates oxyfluorfen rates of 70 to 105 g ha−1, and these rates provide common purslane and prostrate pigweed control that growers would find acceptable. Registration of the water-based formulation of oxyfluorfen would provide growers an opportunity to control weeds and reduce the need for hand labor.

Atrazine is an important herbicide for broadleaf weed control in corn. Use rates have declined in many corn production systems due to environmental concerns and the availability of other effective herbicides, especially glyphosate in glyphosate-resistant hybrids. However, using multiple effective herbicide modes of action is ever more important because occurrence of herbicide-resistant weeds is increasing. An experiment to compare application timings of reduced rates of atrazine to benefit resistance management in broadleaf weeds while protecting corn yield was conducted in Wisconsin across four site-years in 2012 and 2013. Herbicide treatments consisted of five atrazine rate and timing combinations and three POST base herbicides: glyphosate, glufosinate, and tembotrione. Metolachlor was applied PRE at 2.1 kg ai ha−1 for grass control in all treatments. A linear regression model estimated that atrazine rates ≥ 1.0 kg ai ha−1 applied PRE would prevent exposure of common lambsquarters plants to POST herbicides, but giant ragweed and velvetleaf exposure was not influenced by timing. Corn yield was also not influenced by atrazine rate and timing combinations at the α = 0.05 level; however, at P = 0.06, corn yield was greater for atrazine applied PRE at 1.1 kg ha−1 than for atrazine applied PRE at 0.5 kg ha−1, POST at 1.1 kg ha−1, or not at all. In summary, higher rates of atrazine applied PRE may improve yield, as reported by others, but this study concludes reduced rates of atrazine (i.e., ≤ 1.1 kg ha−1) applied to corn in a POST tank mixture combination provided more consistent control of giant ragweed, velvetleaf, and common lambsquarters compared with atrazine applied PRE. This information should help direct atrazine application timing applied POST when applied at low rates to improve proactive herbicide resistance management.

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%.

Herbicide resistance to several of the most common weed species in US rice production, such as barnyardgrass and red rice, has made weed control extremely difficult with available herbicide options. No very-long-chain fatty acid–inhibiting herbicides are labeled for use in US rice; however, pethoxamid is one such herbicide under development for soil-applied use to control grasses and small-seeded broadleaves in rice and various row crops. Field trials were conducted in 2015 and 2016 near Stuttgart, AR, for rice tolerance and in 2016 near Colt, AR, and Lonoke, AR, for weed control with the use of pethoxamid-containing rice herbicide programs. Pethoxamid was applied alone and in a program at 420 and 560 g ai ha–1 with other herbicides labeled in rice including clomazone, quinclorac, propanil, imazethapyr, and carfentrazone POST. Injury less than 10% was seen for all treatments 2 wk after application in 2015 and 2016, except for pethoxamid at 420 g ha–1 to clomazone to one-leaf rice. Rice injury dissipated to less than 5% following all treatments by 4 wk after flood establishment. Barnyardgrass was controlled 95% or more near Colt and 93% or more near Lonoke for herbicide programs including clomazone PRE followed by pethoxamid plus quinclorac or imazethapyr at three- to four-leaf stage rice. Considering the minimal injury and high levels of barnyardgrass control associated with pethoxamid-containing weed control programs, pethoxamid provides a unique and effective site of action for use in US rice production.

WideStrike® Acala cotton is a two-gene, in-plant trait that provides broad-spectrum and season-long control of lepidopteran insect pests, and the varieties available in California also have resistance to glyphosate. There have been indications that WideStrike cotton has some glufosinate tolerance as well, so the level of tolerance to glufosinate needed to be ascertained. A 2-yr (2008 and 2009) study was conducted in California to evaluate the potential crop injury caused by three different rates (0.59, 0.88, and 1.76 kg ai ha−1) of glufosinate–ammonium at four different growth stages (cotyledon, 2-node, 5- to 6-node, and 18- to 19-node stages) of WideStrike Acala cotton. The effects of these treatments on the cotton plants and yield were closely monitored. Glyphosate at 1.54 kg ae ha−1 was applied at all cotton growth stages as a standard application, and a nontreated control was included. The greatest level of injury (58%) was observed with the highest rate of glufosinate applied at both the cotyledon and the two-node stage of cotton. However, injury was less than 10% following glufosinate at 0.59 kg ha−1 applied at the 18- to 19-node stage. The level of injury increased with the higher application rate of glufosinate at all crop growth stages. In 2008 and 2009, the glufosinate treatments had no effect on cotton lint yield. Therefore, the study showed that glufosinate can be applied safely topically at 0.59 kg ha−1 at the cotyledon- to 2-node stage or as POST-directed spray between the 5- to 19-node stages. Although injury occurred at this rate, the plants recovered within 2 to 3 wk of the treatment. Increasing glufosinate rates beyond 0.59 kg ha−1 can increase the possibility of greater crop injury.

Atrazine offers growers a reliable option to control a broad spectrum of weeds in grain sorghum production systems when applied PRE or POST. However, because of the extensive use of atrazine in grain sorghum and corn, it has been found in groundwater in the United States. Given this issue, field experiments were conducted in 2017 and 2018 in Fayetteville and Marianna, Arkansas, to explore the tolerance of grain sorghum to applications of assorted photosystem II (PSII)-inhibiting herbicides in combination with S-metolachlor (PRE and POST) or mesotrione (POST only) as atrazine replacements. All experiments were designed as a factorial, randomized complete block; the two factors were (1) PSII herbicide and (2) the herbicide added to create the mixture. The PSII herbicides were prometryn, ametryn, simazine, fluometuron, metribuzin, linuron, diuron, atrazine, and propazine. The second factor consisted of either no additional herbicide, S-metolachlor, or mesotrione; however, mesotrione was excluded in the PRE experiments. Crop injury estimates, height, and yield data were collected or calculated in both studies. In the PRE study, injury was less than 10% for all treatments except those containing simazine, which caused 11% injury 28 d after application (DAA). Averaged over PSII herbicide, S-metolachlor–containing treatments caused 7% injury at 14 and 28 DAA. Grain sorghum in atrazine-containing treatments yielded 97% of the nontreated. Grain sorghum receiving other herbicide treatments had significant yield loss due to crop injury, compared with atrazine-containing treatments. In the POST study, ametryn- and prometryn-containing treatments were more injurious than all other treatments 14 DAA. Grain sorghum yield in all POST treatments was comparable to atrazine, except prometryn plus mesotrione, which was 65% of the nontreated. More herbicides should be evaluated to find a comparable fit to atrazine when applied PRE in grain sorghum. However, when applied POST, diuron, fluometuron, linuron, metribuzin, propazine, and simazine have some potential to replace atrazine in terms of crop tolerance and should be further tested as part of a weed control program across a greater range of environments.

Limited information exists on the critical time of weed removal (CTWR) with the currently used soybean cultivars in Ontario. A study consisting of eight field experiments was conducted from 2017 to 2019 in Ontario, Canada, to determine the impact of delayed postemergence (POST) herbicide application on soybean yield based on average weed height at application, days after crop emergence (DAE), accumulated crop heat units (CHU) from the date of planting, and soybean growth stage. The regression model estimated the weed size at herbicide application that led to 1%, 2.5%, and 5% yield loss in soybean was 9, 14, and 20 cm under low weed density (averaging 73 to 134 plants m−2) and 3, 4, and 6 cm under high weed density (143 to 153 plants m−2) conditions, respectively. The estimated DAE at herbicide application time that led to 2.5%, 5%, 10%, and 25% yield loss in soybean was 24, 30, 37, and 53 DAE under low weed density and 8, 10, 14, and 23 DAE under high weed density, respectively. The predicted crop stage at herbicide application that resulted in 2.5%, 5%, 10%, and 25% yield loss in soybean was V4, V5, R2, and R5 under low weed density and VE, VC, V1, and V4 under high weed density, respectively. This study concludes that soybean yield loss is influenced by the weed density (low vs/high) and the time of the first POST herbicide application. When the first POST herbicide application was delayed until soybean was at the V2 stage the monetary loss was Can$20.46 and Can$221.20 ha−1 in low and high weed-density environments, respectively.

Field studies were conducted in 1992 and 1993 to evaluate weed control by 15 herbicide treatments in wheat stubble and in the succeeding corn crop. Atrazine at 2.24 kg ai/ha plus several herbicide treatments were applied about 13, 21, and 33 d following winter wheat harvest on separate plots in 1992 and 1993 in a soybean–winter wheat–corn rotation. Atrazine with and without 2,4-D isooctyl ester at 1.46 kg ae/ha or dicamba at 0.36 kg ae/ha did not control barnyardgrass, green foxtail, horseweed, kochia, stinkgrass, tumble thistle, or witchgrass in the wheat stubble 30 d after treatment. Atrazine mixtures containing glyphosate or paraquat with or without 2,4-D or dicamba controlled most summer annual weed species. Atrazine plus paraquat at 0.43 kg ai/ha was more effective on redroot pigweed and tumble thistle than atrazine plus glyphosate at 0.43 kg ae/ha plus 2,4-D at 0.95 kg ae/ha. Atrazine plus glyphosate mixtures were more effective on barnyardgrass for the first and second application date than atrazine plus paraquat. Increasing the glyphosate rate from 0.43 to 0.67 kg/ha was necessary to control barnyardgrass 95% at the first date. With the first date of application, kochia control was greater when 2,4-D or dicamba was added to the atrazine plus paraquat (0.43 kg/ha) mixture. Although annual grass control was generally greater when weeds approached maturity, early applications are a more sound weed control strategy because of soil water conservation and prevention of weed seed production. However, corn yields in 1993 were greater on plots treated at the third application in 1992 because weed biomass in corn was less. In 1994, corn yields were highest for the first application in 1993, probably because of better weed control in the corn. Above average rainfall in 1993 and 1994 aided corn yields.

Junglerice is becoming more prevalent in Tennessee, Arkansas, and Mississippi row crop fields. The evolution of glyphosate-resistant (GR) junglerice populations is one reason for the increase. Another possible explanation is that glyphosate and clethodim grass activity is being antagonized by dicamba. This question has led to research to examine whether sequential applications alleviate antagonism observed with dicamba plus glyphosate and/or clethodim mixtures and determine whether sequential treatments with those herbicides at 24 h, 72 h, or 168 h can improve junglerice control. Glyphosate + clethodim applications provided >90% junglerice control. The observed levels of antagonism varied by whether the location of the test was in the greenhouse or the field, and the timing of applications. In the greenhouse, clethodim + dicamba provided excellent control, whereas in the field, the same treatment showed a greater than 30% reduction in junglerice control compared with clethodim alone. However, control was restored by using a mixture of glyphosate + clethodim without dicamba. The environment at the time of application and relative GR level of the junglerice influenced the overall control of these sequential applications. When clethodim applied first followed by dicamba at 72 h or 168 h, better control was observed compared with applying dicamba followed by clethodim. Overall, mixing glyphosate + clethodim provided the most complete junglerice control regardless of timing. These data confirm that leaving dicamba out of the spray tank will mitigate herbicide antagonism on junglerice control. These data would also indicate that avoiding dicamba and glyphosate mixtures will also improve the consistency of control with glyphosate-susceptible junglerice.

Limited information exists on the tolerance of processing tomato to postemergence (POST) application of thifensulfuron-methyl. The tolerance of 13 processing tomato varieties, ‘CC337’, ‘H9144’, ‘H9314’, ‘H9478’, ‘H9492’, ‘H9553’, ‘H9909’, ‘N1069’, ‘N1082’, ‘N1480E’, ‘N1480L’, ‘N1522’, and ‘PETO696’, to POST applications of thifensulfuron-methyl at the maximum use rate (6 g ai/ha) and twice the maximum use rate (12 g/ha) for soybean was evaluated at two Ontario locations in 2001 and 2002. At 7 days after treatment (DAT), thifensulfuron applied POST caused 0.2 to 1% visible injury to CC337, H9144, N1082, N1522, and PETO696 at the high rate. H9553, H9909, N1069, and N1480E were the most sensitive to POST thifensulfuron-methyl, with visible injury ranging from 1 to 6% at the high rate. There was no visible injury to H9314, H9478, H9492, or N1480L at either application rate of thifensulfuron-methyl. By 28 DAT, no visible injury was noted to any variety, except for H9909, N1069, and N1480L, which showed minimal (<2%) visible injury. There were no adverse effects on shoot dry weight and marketable yield for any variety at either rate. Although thifensulfuron-methyl applied POST caused minimal and transient injury to the varieties tested, more tolerance trials with other fresh and processing tomato varieties are required to confirm these initial results.