Clomazone was labeled for rice in 2001; however, that label excluded its use on coarse- (light) textured soils, including sand, loamy sand, and sandy loam with less than 1% organic matter due to rice injury. Field studies conducted in 2005, 2006, and 2007 evaluated weed control and tolerance of rice to early postemergence (EPOST) applications of clomazone alone and tank mixed with other herbicides on sandy loam and clay loam soils. At 42 d after treatment (DAT), broadleaf signalgrass (BRAPP) and barnyardgrass (ECHCG) control was > 86%. At 14 DAT, rice injury was greatest (13%) from clomazone applied preemergence (PRE) at 0.44 kg ai/ha on sandy soil. Annual sedge (CYPCP) control was > 78% on sandy loam soils at 14 DAT, but increased to > 90% by 42 DAT. On clay loam soils, CYPCP control at 42 DAT ranged from 60 to 76% from clomazone alone or tank mixed with cyhalofop or fenoxaprop. All other tank mixes provided > 80% control. Hemp sesbania (SEBEX) control was > 80% from all tank mixes. Clomazone alone provided < 77% control. Data suggest that clomazone can be used EPOST in combination with other herbicides without causing significant rice injury on sandy loam soils in Texas.

Experiments were conducted at three North Carolina research stations in 2003 to evaluate weed control and corn yield in glyphosate-resistant, glufosinate-resistant, imidazolinone-tolerant, and conventional corn weed management systems. Late-season control of common lambsquarters, large crabgrass, and yellow nutsedge increased with metolachlor PRE compared with no PRE herbicide treatment. Common lambsquarters, pitted morningglory, entireleaf morningglory, spurred anoda, and tropic croton control was improved by a single early POST (EPOST) application regardless of herbicide system. Control of common lambsquarters, pitted morningglory, entireleaf morningglory, and spurred anoda was similar for glyphosate and glufosinate systems for each POST over-the-top (POT) herbicide system. A single EPOST application of imazethapyr plus imazapyr to imidazolinone-tolerant corn controlled common lambsquarters, pitted morningglory, entireleaf morningglory, and spurred anoda and was better than a single EPOST application of glyphosate, glufosinate, or nicosulfuron. Tropic croton was controlled ≥ 95% with glufosinate or glyphosate, applied once or twice, or in mixture with metolachlor. A single EPOST application of imazethapyr plus imazapyr or nicosulfuron did not control tropic croton. Common lambsquarters, entireleaf morningglory, large crabgrass, Palmer amaranth, and yellow nutsedge control was greater with a late-POST–directed (LAYBY) of ametryn than no LAYBY. Systems that did not include a POT herbicide system had the lowest percentage in the weed-free yield and the lowest yield. Treatments that included a POT system with or without a PRE treatment of metolachlor yielded within 5% of the weed-free treatment, regardless of herbicide system.

Experiments were conducted from 2003 through 2006 to compare annual grass control by graminicides applied alone or with other pesticides and to determine whether graminicide formulation affected annual grass control and interactions with co-applied pesticides. Formulation and rate had no affect on broadleaf signalgrass or large crabgrass control by clethodim. The efficacy of clethodim in tank mixtures with acifluorfen plus bentazon, bentazon, chlorothalonil, imazapic, pyraclostrobin, or tebuconazole were not affected by clethodim formulation. Broadleaf signalgrass and large crabgrass control by clethodim was slightly reduced by acifluorfen plus bentazon, chlorothalonil, imazapic, and pyraclostrobin, but not by tebuconazole. Chlorothalonil and pyraclostrobin reduced broadleaf signalgrass control with quizalofop-P but did not reduce fall panicum control. Azoxystrobin, propiconazole, and tebuconazole did not affect efficacy of quizalofop-P.

Peanuts are not often used as a true oilseed crop, especially for the production of fuel. However, peanut could be a feedstock for biodiesel, especially in on-farm or small cooperative businesses, where producers can dictate the cost of making their own fuel. Field studies were conducted in 2005 and 2006 to assess low-cost weed-control systems for peanuts that would facilitate the economic viability of peanut biodiesel. Four preselected herbicide costs ranging from $25 to $62/ha and two application timings were compared with nontreated ($0/ha) and typical ($115/ha) herbicide programs for weed control and peanut oil yield. A peanut oil yield goal of 930 L/ha was exceeded with multiple low-cost herbicide systems in 3 of 4 site–yr. The main effect of application timing was only significant for a single site–year in which oil yield increased linearly with cost of the PRE and POST weed-control system. An herbicide cost of $50/ha, using PRE and POST applications, was consistently among the highest in oil yield, regardless of site–year, exceeding the typical (high value) programs in 3 of 4 site–yr. Use of reduced rates of imazapic (0.5× or 0.035 kg ai/ha) was detrimental in 2 of 4 site–yr. Weed control, and thus oil yields, were most dependent on species present at each location and not on input price. Data from this series of studies will allow researchers and entrepreneurs to more accurately assess the viability and sustainability of peanut biodiesel.

Field experiments were conducted in 1999 and 2000 to evaluate early POST (EPOST) and late POST (LPOST) control of common ragweed and giant foxtail with mesotrione at 70, 105, and 140 g ai/ha alone and in mixtures with glufosinate at 300 g ai/ha in glufosinate-resistant corn. Glufosinate-resistant corn injury was frequently higher with mixtures of mesotrione plus glufosinate than with mesotrione applied alone. Mixtures of mesotrione with glufosinate applied EPOST injured corn 6 to 21% in 1999, but in 2000, injury from mixtures was 23 to 30% from LPOST applications. Common ragweed control was above 77% with all treatments, which included 105 g/ha mesotrione. Giant foxtail control was higher at 76 to 78% by mixtures of mesotrione with glufosinate applied LPOST than by mesotrione alone. Corn yields were highest when glufosinate was included in treatments at either application timing. In the greenhouse, mixtures of mesotrione with glufosinate-injured glufosinate-resistant corn 11% or less, but corn biomass was reduced by 25% for the mixture of mesotrione at 105 g/ha plus glufosinate at 350 g/ha. Mixtures of mesotrione with glufosinate can be more effective than mesotrione alone but control of common ragweed and giant foxtail might not be commercially acceptable.

Experiments were conducted at the Lonoke Extension and Applied Research Center greenhouse at Lonoke, AR, to evaluate the effects of urea ammonium nitrate (UAN) on bispyribac and penoxsulam efficacy on barnyardgrass, hemp sesbania, and broadleaf signalgrass. Herbicide treatments included bispyribac at 17.9 or 35.8 g ai/ha or penoxsulam at 24.4 or 48.9 g ai/ha tank mixed with (1) no adjuvant, (2) a nonionic organosilicone (OSL) adjuvant at 0.125% v/v, (3) a methylated seed oil/organosilicone (MSO/OSL) adjuvant at 0.37 L/ha, (4) a proprietary blend of MSO/OSL/UAN at 2% v/v, (5) UAN at 2% v/v, (6) OSL at 0.125% plus UAN at 2% v/v, or (7) MSO/OSL at 0.37 L/ha plus UAN at 2% v/v. In addition to these adjuvants, penoxsulam was also applied with crop oil concentrate (COC) at 2.34 L/ha and with COC at 2.34 L/ha plus UAN at 2% v/v. The addition of UAN to either herbicide plus an adjuvant increased herbicide efficacy on barnyardgrass in the greenhouse, with 95 to 99% biomass reduction of three- to four-leaf barnyardgrass and 88 to 92% biomass reduction of one- to three-tiller barnyardgrass. UAN did not generally increase efficacy on hemp sesbania, as control was 90% or higher with treatments containing either herbicide and a recommended adjuvant. Adding UAN did not increase efficacy on broadleaf signalgrass. Broadleaf signalgrass control was highly variable and no treatment provided more than 65% biomass reduction.

Bensulfuron-methyl (BSM) has been one of the most widely used herbicides in Chilean rice fields because it controls a wide spectrum of weeds and does not require field drainage for application. However, failures of BSM to control water plantain in rice fields have been noted since 2002. We assessed BSM effects on suspected resistant (CU1 and CU2) and susceptible (AN1) water plantain accessions collected in Chilean rice fields during 2004 and 2005. BSM rates resulting in 50% growth reduction () of CU2 and CU1 plants were 12- and 33-fold higher than for AN1 plants, respectively. Acetolactate synthase (ALS) activity assays in vitro suggested resistance in CU1 and CU2 was due to an ALS enzyme with reduced BSM sensitivity compared to the AN1 biotype. Resistance indices (RI), or ratios of the resistant to susceptible values (BSM rate to inhibit ALS-enzyme activity by 50%), were 266 (CU2/AN1) and > 38,462 (CU1/AN1). This agreed with in vivo ALS activity assays where RI were 224 (CU2/AN1) and > 8,533 (CU1/AN1). Resistance levels detected in whole-plant or in vivo ALS activity assays were orders of magnitude lower than those detected in in vitro ALS activity studies suggesting nontarget site mechanisms may have mitigated BSM toxicity. However, a consistent ranking of BSM sensitivity levels (AN1 > CU2 > CU1) throughout all three types of assays suggests resistance is primarily endowed by low target site sensitivity. We conclude that susceptible and resistant water plantain biotypes coexist in Chilean paddies, and the use of integrated weed management involving herbicides with a different mode of action would be imperative to prevent further evolution of resistance to BSM and possibly cross-resistance to other ALS inhibitors. In vitro ALS-enzyme assays provided the best discrimination of resistance levels between biotypes.

Experiments were conducted at Manhattan, KS in 2005 and 2006 to evaluate cotton response to simulated 2,4-D and dicamba drift rates at different stages of growth and multiple applications of 2,4-D. Cotton was treated with 2,4-D and dicamba at 0, 1/200, and 1/400 of the use rate (561 g ae/ha) when plants were at the three- to four-leaf, 8-, 14-, or 18-node growth stages. Injury symptoms after 2,4-D and dicamba application were more severe at the three- to four-leaf stage compared with other stages with greatest injury from 2,4-D. In general, plants partially recovered from 2,4-D and dicamba injury symptoms, and only 2,4-D applied at the 1/200 rate reduced fiber yield. In a separate study, cotton was treated with 2,4-D at 0, 1/400, 1/800, and 1/1,200 of the use rate for one, two, or three applications. Yield reduction increased as herbicide rate increased from 1/1,200 to 1/400 and the number of applications increased from one to three. In both studies, plants partially or fully recovered from injury symptoms and recovery was greater with dicamba than 2,4-D. Correlation coefficient analysis showed that visual injury ratings later in the growing season are a good predictor of yield reduction (R2 = 0.58).

Greenhouse studies were conducted to evaluate the nature of the cotton postemergence (POST) herbicides followed by (fb) MSMA postemergence-directed (LAYBY) for foliar and tuber reduction of yellow and purple nutsedge when applied to nutsedge at two different application timings. Trifloxysulfuron at 4 and 6 g ai/ha fb MSMA LAYBY reduced 10- to 15- and 20- to 30-cm purple and yellow nutsedge root and shoot dry weights by at least 56%. However, the effect of weed size at the time of application was significant for trifloxysulfuron at 6 g/ha for percent root and shoot reductions in yellow nutsedge and percent root reduction in purple nutsedge. Significance of herbicide rate was only observed for percent shoot and root reduction of 10- to 15-cm yellow nutsedge. Trifloxysulfuron treatments reduced purple and yellow nutsedge shoot and root dry weights equivalent to treatments involving glyphosate POST fb MSMA LAYBY. MSMA at 1,120 and 2,240 g/ha and glufosinate POST fb MSMA LAYBY were effective for reducing purple and yellow nutsedge shoot dry weights, although percent reduction was influenced by nutsedge height at herbicide application. Treatments involving pyrithiobac POST fb MSMA LAYBY slightly increased 10- to 15-cm yellow nutsedge root dry weights. MSMA at either rate produced additive responses when included in tank mixtures with trifloxysulfuron at either rate or pyrithiobac POST fb MSMA LAYBY in yellow nutsedge. Other tank mixes or sequential combinations did not cause additive or synergistic responses.

Experiments were conducted to evaluate the effect of application rate, growth stage, and tank mixing azimsulfuron, bentazon, MCPA, propanil, or cyhalofop on the efficacy of bispyribac–sodium against early watergrass and late watergrass from rice fields in northern Greece. Mixtures of bispyribac–sodium with the insecticides carbaryl, diazinon, and dichlorvos were also evaluated. Bispyribac–sodium (24 to 36 g ai/ha) applied alone at the three- to four-leaf growth stage provided 89 to 100% control of early watergrass and 84 to 100% control of late watergrass. When bispyribac–sodium was applied alone at the five- to six-leaf growth stage of early watergrass and late watergrass, control ranged from 78 to 100% and 71 to 100%, respectively. Mixtures of bispyribac–sodium with azimsulfuron provided better control of both species at any growth stage than bispyribac–sodium applied alone. On the contrary, mixtures of bispyribac–sodium with bentazon, MCPA, or propanil were less effective on both species at any growth stage than bispyribac–sodium applied alone. A slight efficacy reduction occurred on both species for the mixture of bispyribac–sodium with cyhalofop. Mixtures of bispyribac–sodium with the insecticides carbaryl or dichlorvos showed reduced efficacy on both species, whereas increased efficacy on both species was observed for mixtures of bispyribac–sodium with diazinon as compared with the single application of bispyribac–sodium.

Field studies were conducted in 2006 and 2007 to evaluate strategies for management of four glyphosate-tolerant common lambsquarters populations in glyphosate-resistant soybeans. Treatments consisted of several different preplant herbicide combinations followed by one or two postemergence applications of 0.84 to 3.36 kg ae/ha of glyphosate. Preplant application of a combination of glyphosate, 2,4-D ester and residual herbicides resulted in the most effective control of all populations, and allowed use of a single postemergence glyphosate application at the lowest rate. Late-season control of common lambsquarters ranged from 66 to 95% where no preplant herbicides were applied, 72 to 97% for preplant application of glyphosate and 2,4-D, and 96 to 100% for the combination of glyphosate, 2,4-D, flumioxazin, and cloransulam-methyl. Individual plants survived and produced seed following single postemergence glyphosate applications of 3.36 kg ae/ha, and multiple glyphosate applications totaling 2.5 kg ae/ha. Multiple postemergence treatments were more effective than single postemergence treatments for reduction of common lambsquarters population density and seed production. The progeny of plants that survived high rates of glyphosate in the field were screened for their response to glyphosate in the greenhouse. Progeny from one of three populations exhibited increased glyphosate tolerance from 1 yr of selection pressure.

Field studies were conducted in 2004 and 2005 in Michigan to determine the effect of seeding establishment method and weed control on forage quality of glyphosate-resistant alfalfa in the establishment year. Seeding methods included alfalfa only (clear-seeding) and alfalfa with a companion crop of oat (companion-seeding). Herbicide treatments included an untreated control and glyphosate treatment for both establishment systems, and either imazamox in the clear-seeding system or imazamox + clethodim in the companion-seeding system. The greatest differences among treatments in forage quality were observed at the first harvest in both establishment years. Results suggest high quality, productive alfalfa stands can be established utilizing glyphosate-resistant alfalfa in a clear seeding system.

Trials were established in 2003, 2004, and 2005 in Ontario to determine the effects of residues of mesotrione, atrazine, and mesotrione plus atrazine 1 and 2 yr after application on broccoli, carrot, cucumber, onion, and potato. One yr after mesotrione application, injury was 43, 37, 18, 24, and 0% in broccoli, carrot, cucumber, onion, and potato, respectively. The addition of atrazine to mesotrione in the year before planting increased injury to 55, 53, 30, 42, and 3% in broccoli, carrot, cucumber, onion, and potato, respectively. Plant dry weight and yield were also decreased by mesotrione residues the year after application in all crops except potato. The addition of atrazine to mesotrione accentuated the reduction in dry weight and yield in broccoli, carrot, cucumber, and onion. There was no injury, or reductions in dry weight or yield in any crop planted 2 yr after application of mesotrione alone or in tank mix with atrazine. A recropping interval of 2 yr is recommended following applications of mesotrione or mesotrione plus atrazine for broccoli, carrot, cucumber, and onion. Potato can be safely planted the year following application of mesotrione plus atrazine.

Knowledge of weed community structure in vegetable crops of the north central region (NCR) is poor. To characterize weed species composition present at harvest (hereafter called residual weeds) in processing sweet corn, 175 fields were surveyed in Illinois, Minnesota, and Wisconsin from 2005 to 2007. Weed density was enumerated by species in thirty 1-m2 quadrats placed randomly along a 300- to 500-m loop through the field, and additional species observed outside quadrats were also recorded. Based on weed community composition, population density, and mean plant size, overall weed interference level was rated. A total of 56 residual weed species were observed and no single species dominated the community of NCR processing sweet corn. Several of the most abundant species, such as common lambsquarters and velvetleaf, have been problems for many years, while other species, like wild-proso millet, have become problematic in only the last 20 yr. Compared to a survey of weeds in sweet corn more than 40 yr ago, greater use of herbicides is associated with reductions in weed density by approximately an order of magnitude; however, 57% of fields appeared to suffer yield loss due to weeds. Sweet corn harvest in the NCR ranges from July into early October. Earlier harvests were characterized by some of the highest weed densities, while late-emerging weeds such as eastern black nightshade occurred in fields harvested after August. Fall panicum, giant foxtail, wild-proso millet, common lambsquarters, and velvetleaf were the most abundant species across the NCR, yet each state had some unique dominant weeds.

Volunteer potato is a major weed pest of sweet corn in regions where winter soil temperatures fail to kill tubers left in the ground after harvest. Studies were conducted in 2004 to 2005 to determine the effect of combining atrazine with mesotrione applied POST on volunteer potato control and new tuber production in sweet corn. Mesotrione at 0.035, 0.07, and 0.1 kg/ha and atrazine at 0.3, 0.6, and 1.1 kg/ha were applied alone and in all possible combinations when volunteer potato ranged from 5 to 12 cm tall. Mesotrione applied alone at all rates, atrazine at 1.1 kg/ha, or mesotrione plus atrazine combinations reduced the number of new tubers produced to ≤ 1.1 per plant compared with 11 tubers per plant in nontreated checks. Potatoes treated with atrazine alone at 0.3 or 0.6 kg/ha produced 3.3 or 1.9 tubers per plant, respectively, which could lead to volunteer potato problems in the succeeding crop. Sweet corn yield was not affected by herbicide treatment in 2004 but was reduced in 2005 when atrazine was used alone at 0.3 or 0.6 kg/ha because of poor control of volunteer potato. Additional studies were conducted from 2004 to 2006 to determine volunteer potato control in sweet corn in reduced and conventional tillage and treated with fluroxypyr, mesotrione, or no herbicide. Volunteer potato control was improved and the number and weight of tubers was reduced 79 and 91%, respectively, in conventionally tilled plots treated with fluroxypyr compared with reduced-tillage plots. Control of volunteer potato with mesotrione was greater than 98% and reduced tuber number and weight greater than or equal to all other treatments regardless of tillage level.

Field experiments were conducted in 1999, 2000, and 2001 to investigate PRE and POST applications of halosulfuron-methyl in combination with clomazone plus ethalfluralin for control of sedge and smooth pigweed in summer squash. Halosulfuron was applied PRE or POST to summer squash at 9, 18, or 27 g ai/ha in combination with a PRE application of clomazone at 175 g ai/ha plus ethalfluralin at 630 g ai/ha. Smooth pigweed control by addition of halosulfuron at 18 and 27 g/ha in combination with clomazone plus ethalfluralin PRE was greater than 89% independent of application method. Yellow nutsedge control was greater than 83% with POST applications of halosulfuron at 18 and 27 g/ha in combination with clomazone plus ethalfluralin PRE. Yellow nutsedge control was greater than 60% from all POST halosulfuron applications at 9, 18, or 27 g/ha in the greenhouse. In a separate field study without ethalfluralin PRE, rice flatsedge control was more than 85% from halosulfuron applied POST at 18 and 27 g/ha. Yellow summer squash and zucchini squash were injured as much as 52 and 47%, respectively, from inclusion of halosulfuron PRE or POST at 27 g/ha in treatments. Summer squash yields were generally not affected by halosulfuron rate, and were comparable to or higher than summer squash treated by only the mixture of clomazone plus ethalfluralin. In these studies, summer squash were injured by halosulfuron applied at 9 to 27 g/ha PRE or POST, yet rapidly recovered, making this herbicide acceptable for use in combination with clomazone and ethalfluralin for controlling several common weed species.

The use of POST herbicides has been limited in sweet corn because of the narrow spectrum of weed control or potential crop injury. Field experiments were conducted to evaluate the 4-hydroxyphenyl pyruvate dioxygenase (HPPD)-inhibiting herbicides mesotrione, tembotrione, and topramezone applied POST in sweet corn at three locations. Efficacy of mesotrione, tembotrione, and topramezone applied alone or mixed with atrazine was compared to other labeled POST herbicides following PRE S-metolachlor. Giant foxtail control was greater with tembotrione or topramezone than mesotrione alone or mixed with atrazine. Common lambsquarters, velvetleaf, and common ragweed were controlled 98% or greater with the HPPD-inhibiting herbicides when mixed with atrazine. Tolerance of six sweet corn hybrids was determined in the field when treated with 1× and 2× rates of these herbicides mixed with atrazine. Tolerance of six sweet corn hybrids to these herbicides was determined in the greenhouse when treated with 0.5, 1, 2, 4, 8, and 16 times the labeled rate. Differential hybrid tolerance to each herbicide was observed in both the field and greenhouse evaluations. Tembotrione killed ‘Merit’ in both evaluations. Excluding Merit, hybrids generally had good tolerance to tembotrione and topramezone in the field, but had differential tolerance to mesotrione. With the exception of Merit, hybrids generally had greater tolerance to tembotrione than topramezone and less tolerance to mesotrione in the greenhouse. These HPPD-inhibiting herbicides provide POST weed control, but the potential for sweet corn injury varies among the herbicides and hybrids and warrants further characterization.

Applications of metribuzin plus MSMA have been used to control goosegrass in bermudagrass turf for over 20 yr. In 2003, two goosegrass biotypes on the island of Kauai, Hawaii were found to be resistant to applications of metribuzin plus MSMA. Metribuzin plus MSMA applied at rates of 0.28 kg ai/ha plus 2.2 kg/ha, respectively, followed by MSMA at 2.2 kg/ha 7 d later, provided 100% control of two susceptible goosegrass biotypes, but no control of two resistant biotypes. At the flowering growth stage, metribuzin applied at a rate of 0.28 kg/ha controlled both susceptible biotypes (> 92%), but did not control the two resistant biotypes. Two applications of MSMA applied at a rate of 2.2 kg/ha (7 d apart) did not control any of the four biotypes at the flowering growth stage. The two resistant biotypes were approximately 100 to 200 times less sensitive to increasing rates of metribuzin than the two susceptible biotypes. The two biotypes that were resistant to metribuzin plus MSMA were also resistant to applications of simazine plus MSMA. However, all four biotypes were susceptible to applications of glyphosate and foramsulfuron.

Diflufenzopyr is an auxin-transport inhibitor that can increase the phytotoxicity of certain auxin-mimicking herbicides such as dicamba on broadleaf species. Dicamba is commonly used alone and in combination with other auxin herbicides for broadleaf weed control in various species of turfgrass. Dicamba efficacy applied over a series of rates either alone or as an admixture with either 20 or 40% by weight of diflufenzopyr relative to the weight of dicamba was evaluated on purple cudweed and common lespedeza. The 20% admixture reduced the LD50 of dicamba on purple cudweed from 23 to 20 g/ha. Similarly, LD50 on common lespedeza was reduced from 36 and 27 g/ha. The 20% admixture was 13 and 25% more active than dicamba alone for these two weed species, respectively. However, the synergistic benefit was limited to a relatively narrow range of rates that are below the minimal registered rate of dicamba. Turfgrass injury, as expressed by the suppression of foliage growth, was similar whether dicamba was applied alone or with diflufenzopyr for all species evaluated except St. Augustinegrass. The admixture was less injurious than dicamba alone in St. Augustinegrass. The synergistic benefit with respect to weed control was obtained without a corresponding increase in injury on the turfgrasses.

Field trials were conducted at three California locations near Oxnard, Salinas, and Watsonville from 2002 to 2006 to evaluate broadleaf weed control and tolerance of strawberry to oxyfluorfen. Oxyfluorfen applied at 0.3 and 0.6 kg/ha before strawberry transplanting reduced densities of broadleaf weeds such as California burclover, hairy nightshade, little mallow, shepherd's-purse, and yellow sweetclover 70 to 100% compared with nontreated plots but did not control horseweed. Oxyfluorfen application resulted in 9% and 19% greater visible injury to strawberry for the two rates, respectively, compared with nontreated plants in 1 yr but did not reduce strawberry yield. After oxyfluorfen application at 0.6 kg/ha, strawberry plants had 5 to 48% more injury than nontreated plants in subsequent years but early-season yields were similar. Hand-weeding time was reduced 30 to 50% compared with nontreated plots regardless of oxyfluorfen rate. Both water-based and solvent-carrier formulations of oxyfluorfen resulted in similar weed control, strawberry injury, and fruit yield. Plastic mulch installation after oxyfluorfen application but before planting reduced injury to strawberry more than 50% compared with nonmulched beds. Oxyfluorfen applied 30 d before strawberry transplanting had similar crop injury and yield to applications made 15 and 7 d before planting. These results suggest that oxyfluorfen can be used safely in California plasticulture strawberry production for control of common weed species and to reduce labor inputs associated with hand weeding.