Efficacy Of Saflufenacil Research Articles

Efficacy of Saflufenacil for Dry Bean and Annual Weed Desiccation

The efficacy of saflufenacil for desiccating dry bean and annual weeds may be influenced by application rate, single or sequential applications, adjuvant selection and rate, and water carrier volume. Five field experiments were conducted from 2021 to 2023 near Exeter and Ridgetown, Ontario, Canada to evaluate the efficacy of saflufenacil applied at two rates, applied once or sequentially, with four adjuvants at various rates, and three water carrier volumes for desiccating dry bean and common weed escapes in Ontario dry bean production. Saflufenacil (25 g ai ha-1) + Merge (1.0 L ha-1) applied with a 200 L ha-1 water carrier volume desiccated dry bean 96, 100, and 100% at 5, 8, and 14 days after application (DAA), respectively; there was no improvement in dry bean desiccation by increasing the rate of Merge to 2.0 L ha-1 or with a sequential application. With saflufenacil (50 g ai ha-1) + Merge (1.0 L ha-1), there was no impact on dry bean desiccation with water carrier volumes of 100, 200, or 300 L ha-1. Dry bean desiccation with saflufenacil (50 g ai ha-1) plus the adjuvants Merge, MSO, AMS, or Merge + AMS was similar. Sequential applications of saflufenacil (25 g ai ha-1) applied twice at a 1-week interval did not improve dry bean desiccation. For weed species desiccation, saflufenacil + Merge desiccated green pigweed (38-100%) and common ragweed (65-96%) most effectively. However, it was less effective on common lambsquarters (0-48%), barnyardgrass (9-24%), and green foxtail (6-14%), with no significant effect of saflufenacil rate, adjuvant selection, adjuvant rate, single vs sequential application, or water carrier volume. This study highlights the potential and limitations of saflufenacil for desiccating dry bean and common weed escapes in Ontario dry bean production.

Efficacy of Various Herbicides for the Control of Perennial Plantago spp. and Effects on Alfalfa Damage and Yield

Broadleaf (Plantago major L.) and buckhorn plantain (Plantago lanceolata L.) are perennial weeds that are notoriously difficult to control in alfalfa cropping systems. Sharpen® (saflufenacil) herbicide has been registered for broadleaf weed control in dormant alfalfa, although it has not been evaluated on plantain control. Field and greenhouse experiments were conducted to determine the efficacy of saflufenacil on plantain control with assessments of damage to alfalfa and effects on yield. In the greenhouse, applications of saflufenacil alone caused greater injury to both broadleaf and buckhorn plantain compared to the non-treated control (NTC). Additionally, applications of saflufenacil in combination with other herbicides (imazethapyr or imazamox) caused the greatest amount of injury to both broadleaf and buckhorn plantain compared to all other commercially available herbicide treatments. However, this injury was not enough to effectively control the weeds and prevent recovery and regrowth over time. In the field, alfalfa did not exhibit damage symptoms, or have reduced yield when treated with saflufenacil compared to the NTC. This research indicates that applications of saflufenacil provided temporary injury throughout the duration of the study to both broadleaf and buckhorn plantain with few negative effects to alfalfa in the field.

Efficacy of Saflufenacil for Control of Glyphosate-Resistant Horseweed (Conyza canadensis) as Affected by Height, Density, and Time of Day

Control of glyphosate-resistant (GR) horseweed in soybean with glyphosate (900 g ai ha−1) plus saflufenacil (25 gaiha−1) has been variable. The objective of this research was to determine the effect of GR horseweed height, density, and time of day (TOD) at application on saflufenacil plus glyphosate efficacy in soybean. All experiments were completed six times during a 2 yr period (2014, 2015) in fields previously confirmed with GR horseweed. Applications from 0900 to 2100 hours provided optimal control of GR horseweed 8 WAA. Soybean yield paralleled GR horseweed control with the highest yield of 3000kgha−1at 1500 hours, and the lowest yield of 2400kgha−1at 0600 hours. The height and density of GR horseweed at application had minimal effect on saflufenacil efficacy. Saflufenacil provided>99% control of GR horseweed when applied to small plants and low densities; however, control decreased to 95% when>25 cm tall, and to 96% in densities>800 plants m−2at 6 WAA due to some plant regrowth. TOD of application had a greater influence on GR horseweed control with saflufenacil than height or density. To optimize control of GR horseweed, saflufenacil should be applied during daytime hours to small plants at low densities. Optimizing GR horseweed control minimizes weed seed return and weed interference.

Influence of Application Variables on the Foliar Efficacy of Saflufenacil on Horseweed (Conyza canadensis)

Greenhouse studies were conducted to determine the influence of spray-solution pH, adjuvant, light intensity, temperature, and glyphosate on the efficacy of saflufenacil on horseweed. Control of glyphosate-resistant horseweed from saflufenacil alone was greatest with a spray-solution pH of 5, compared with pH 7 or 9. However, when glyphosate was added to saflufenacil, similar GR50values were measured with spray solutions adjusted to pH 5 and 9, and horseweed control at pH 9 was 38% greater than at pH 7. The efficacy of saflufenacil on horseweed was 36% greater when crop oil concentrate was used as an adjuvant compared with nonionic surfactant, regardless of the addition of glyphosate or the sensitivity of the horseweed population to glyphosate (resistant vs. susceptible). The addition of glyphosate to low rates of saflufenacil increased control over saflufenacil applied alone on glyphosate-susceptible and -resistant horseweed. Saflufenacil activity was greater under low light intensity (300 μmol m−2s−1) than high light intensity (1,000 μmol m−2s−1). Although initial horseweed control was greater under high temperature (27 C) compared with low temperature (10 C), by 21 d after treatment horseweed dry weight was similar from saflufenacil applied under high and low temperatures.

Utilization of Saflufenacil in a Clearfield® Rice (Oryza sativa) System

Research was conducted in Mississippi in 2012 and 2013 to compare the efficacy of saflufenacil to other broadleaf herbicides applied in mixtures with imazethapyr in a Clearfield rice system. Saflufenacil at 50 g ai ha−1, carfentrazone at 35 g ai ha−1, a prepackaged mixture of halosulfuron plus thifensulfuron at 35 plus 4 g ai ha−1, and a prepackaged mixture of propanil plus thiobencarb at 2,240 plus 2,240 g ai ha−1 were applied in mixture with imazethapyr at 70 g ai ha−1 early-POST (EPOST) to rice in the one- to two-leaf stage or late-POST (LPOST) to rice in the four-leaf to one-tiller stage. No differences in injury among the broadleaf herbicides or between application timings were detected at any evaluation. Imazethapyr combined with propanil plus thiobencarb or saflufenacil provided the greatest control of barnyardgrass 7 and 14 d after treatment (DAT). Hemp sesbania, ivyleaf morningglory, and Palmer amaranth control was greatest and similar for imazethapyr combined with carfentrazone, propanil plus thiobencarb, and saflufenacil; however, rough rice yield was greatest for imazethapyr combined with propanil plus thiobencarb or saflufenacil. Propanil plus thiobencarb or saflufenacil can be used in a Clearfield rice system to achieve optimum weed control and highest rice yields.

Saflufenacil efficacy on horseweed and its interaction with glyphosate

Saflufenacil is a new herbicide on the market and its effectiveness on horseweed, several populations of which have evolved resistance to glyphosate, is not clear. In this research, the effect of adjuvants on the control of horseweed with saflufenacil in the field, the effect of the interaction between glyphosate and saflufenacil on glyphosate‐resistant and glyphosate‐susceptible horseweed and the patterns of uptake and translocation of glyphosate applied alone and in combination with saflufenacil in horseweed were evaluated. The addition of methylated seed oil to saflufenacil provided the best control of horseweed, with crop oil concentrate being intermediate in effect and non‐ionic surfactant ranking as the least‐effective adjuvant. The interaction between glyphosate and saflufenacil was additive with regards to the control of glyposate‐resistant horseweed. The glyphosate‐susceptible horseweed population absorbed 6–13% more 14C‐glyphosate than the glyphosate‐resistant population. The addition of saflufenacil reduced 14C‐glyphosate translocation in both the glyphosate‐resistant and the glyphosate‐susceptible horseweed populations by at least 6%; however, due to the exceptional efficacy of saflufenacil, these reductions did not reduce the level of control. Saflufenacil holds great potential as an alternative control option for glyphosate‐resistant horseweed and is a valuable tool in the management of resistant weeds.

The Influence of Carrier Water pH and Hardness on Saflufenacil Efficacy and Solubility

The pH and hardness of water used as agrochemical carrier can influence herbicide efficacy. The objective of this research was to determine the role of carrier water pH and hardness on saflufenacil efficacy and solubility. Saflufenacil was mixed in eight different carrier waters with one of five pH levels (4.0, 5.2, 6.5, 7.7, 9.0) or one of three hardness levels (0, 310, 620 mg L−1) and applied POST to common lambsquarters and giant ragweed in a field experiment and to field corn in a greenhouse experiment. Solubility testing was also completed on saflufenacil mixed in the five pH levels used in the field and greenhouse experiments. Water hardness did not influence the efficacy of saflufenacil on common lambsquarters, giant ragweed, or field corn. Control of giant ragweed or common lambsquarters in field experiments was reduced by up to 56% when saflufenacil was applied in water with a pH of 4.0 compared with water with a pH of 7.7. When nonsoluble saflufenacil was removed from the spray solution, saflufenacil efficacy on field corn in the greenhouse was reduced by 61% or more when applied in water with a pH of 4.0 than when applied with water with a pH of 5.2 or higher. When nonsoluble saflufenacil was applied with the soluble saflufenacil in the spray solution, at least a 7% reduction in control of field corn was observed when applied in water with pH of 4.0 as compared with saflufenacil applied in water with pH of 5.2 or higher. Solubility of saflufenacil was (1) 10.1 mg L−1in water with a pH of 4.0, (2) 3,461.4 mg L−1in water with a pH of 7.7, and (3) > 5,000 mg L−1at a pH of 9. Some degradation of parent saflufenacil was detected in the pH at 9.0 treatment, with only 90% of added product being recovered after 3 d of storage. This research provides information on how saflufenacil efficacy and solubility is influenced by carrier water pH and potentially explains some differences noticed between field applications of saflufenacil.

The Influence of Adjusting Spray Solution pH on the Efficacy of Saflufenacil

Saflufenacil solubility and efficacy has been shown to be influenced by carrier water pH. This research was conducted to determine if altering the pH of a solution already containing saflufenacil would influence the efficacy of the herbicide. Saflufenacil at 25 g ai ha−1was applied to field corn in carrier water with one of five initial pH levels (4.0, 5.2, 6.5, 7.7, or 9.0) and then buffered to one of four final solution pH levels (4.0, 6.5, 9.0, or none) for a total of twenty treatments. All treatments included ammonium sulfate at 20.37 g L−1and methylated seed oil at 1% v/v. Generally, saflufenacil with a final solution pH of 6.5 or higher provided more dry weight reduction of corn than saflufenacil applied in a final pH of 5.2 or lower. When applying saflufenacil in water with an initial pH of 4.0 or 5.2, efficacy was increased by raising the final solution pH to either 6.5 or 9.0. Conversely, reduction in corn dry weight was less when solution pH of saflufenacil mixed in carrier water with an initial pH of 6.5 or 7.7 was lowered to a final pH of 4.0. When co-applying saflufenacil with herbicides that are very acidic, such as glyphosate, efficacy of saflufenacil may be reduced if solution pH is 5.2 or lower.

Saflufenacil's efficacy as influenced by water hardness and co‐applied herbicides

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Influence of Water Hardness and Co-applied Herbicides on Saflufenacil Efficacy

Influence of Water Hardness and Co-applied Herbicides on Saflufenacil Efficacy

Tank Mix of Saflufenacil with Glyphosate and Pendimethalin for Broad-spectrum Weed Control in Florida Citrus

Citrus (Citrus spp.) is one of the most important crops in Florida agriculture. Weed control is a major component in citrus production practices. If not controlled, weeds may compete with citrus trees for nutrients, water, and light and may also increase pest problems. Herbicides are an important component of integrated weed management program in citrus. Saflufenacil, a new herbicide registered for broadleaf weed control in citrus, can be applied alone or in a tank mix with other herbicides to improve weed control efficacy. A total of six field experiments were conducted in 2008 and 2009 to evaluate the efficacy of saflufenacil applied alone or in a tank mix with glyphosate and pendimethalin for weed control. In addition, experiments were also conducted to evaluate phytotoxicity of saflufenacil applied at different rates and time intervals in citrus. The results suggested that saflufenacil applied alone was usually effective for early season broadleaf weed control; however, weed control efficacy reduced beyond 30 days after treatment (DAT) compared with a tank mix of saflufenacil, glyphosate, and pendimethalin. For example, control of weeds was ≤70% when saflufenacil or glyphosate applied alone compared with tank mix treatments at 60 and 90 DAT. Addition of pendimethalin as a tank mix partner usually resulted in better residual weed control compared with a tank mix of saflufenacil and glyphosate, and this herbicide mixture was comparable with grower's adopted standard treatment of a tank mix of glyphosate, norflurazon, and diuron and several other tank mix treatments. Saflufenacil applied once in a season at different rates or even in sequential applications did not injure citrus trees when applied according to label directions. It is concluded that with its novel mode of action, saflufenacil tank mixed with glyphosate and pendimethalin would provide citrus growers with another chemical tool to control broadleaf and grass weeds.

Efficacy of Saflufenacil plus Dimethenamid-P for Weed Control in Corn

A new, prepackaged mixture of saflufenacil + dimethenamid-P has been introduced for PRE control of grass and broadleaf weeds in corn. Field experiments with this new herbicide combination were conducted in 2008 and 2009 at four locations in southern Ontario, Canada. The objective of this study was to determine the dose of saflufenacil + dimethenamid-P required for overall weed control and species-specific weed control, as well as the dose required for early season weed control when followed with glyphosate at the six- to eight-leaf corn stage. Based on weed dry weight, the GR95 across locations ranged from 126 to 675 g ha−1. The 95% growth reduction (GR95) for common ragweed, common lambsquarters, pigweed, and wild mustard were 933, 325, 186, and 115 g ha−1, respectively. Highest corn yields were achieved with saflufenacil + dimethenamid-P applied alone at doses ranging from 368 to 1470 g ha−1. When followed by glyphosate, the dose range of saflufenacil + dimethenamid-P required to achieve the greatest corn yields was 46 to 1,470 g ha−1. A minimum dose of 184 g ha−1 of saflufenacil + dimethenamid-P followed by glyphosate was required for the yield to exceed that of the single treatment of glyphosate applied alone.

Application timing and adjuvant type affected saflufenacil efficacy on selected broadleaf weeds

Saflufenacil is a new herbicide being developed for pre-plant burndown and pre-emergence broadleaf weed control in field crops, including maize, soybean, sorghum and wheat. Field experiments were conducted in 2007 and 2008 in northeast Nebraska, USA to describe dose-response curves of saflufenacil applied in mid (early post-emergence, EPOST) and late May (late post-emergence, LPOST) with several adjuvants for spring emerging broadleaf weed control. Dose-response curves based on log-logistic model were utilized to determine the ED 90 values (effective dose that provides 90% weed control efficacy) for Convolvulus arvensis, Lactuca serriola, Lamium amplexicaule, Capsella bursa-pastoris, Taraxacum officinale, Thlaspi arvense and Conyza canadensis. In general, weed control efficacy was influenced by application timing and type of adjuvant. EPOST application of saflufenacil resulted better efficacy of saflufenacil compared to LPOST. Addition of spray adjuvants improved efficacy of saflufenacil. For example, 90% control of T. arvense was obtained at EPOST application with 251, 161, 96 and 59 g a.i. ha −1 for saflufenacil applied alone, or tank-mixed with NIS (nonionic surfactant), COC (crop oil concentrate), or MSO (methylated seed oil), respectively. In contrast, the ED 90 values with LPOST application were 333, 201, 127 and 79 g a.i. ha −1 for saflufenacil applied alone, or with NIS, COC and MSO, respectively. MSO was the best adjuvant, which provided the most enhancement of saflufenacil. COC was the second best, or similar to MSO, on many weed species. NIS provided the least enhancement of saflufenacil. The ED 90 values determined for different broadleaf weed species are within the proposed label dose of saflufenacil.

Adjuvants Influenced Saflufenacil Efficacy on Fall-Emerging Weeds

Saflufenacil is a new herbicide being developed for preplant burndown and PRE broadleaf weed control in field crops, including corn, soybean, sorghum, and wheat. Field experiments were conducted in 2006 and 2007 at Concord, in northeast Nebraska, with the objective to describe dose–response curves of saflufenacil applied with several adjuvants for broadleaf weed control. Dose–response curves based on log-logistic model were used to determine the effective dose that provides 90% weed control (ED90) values for six broadleaf weeds (field bindweed, prickly lettuce, henbit, shepherd's-purse, dandelion, and field pennycress). Addition of adjuvants greatly improved efficacy of saflufenacil. For example, the ED90values for field bindweed control at 28 d after treatment were 71, 20, 11, and 7 g/ha for saflufenacil applied alone, or with nonionic surfactant (NIS), crop oil concentrate (COC), or methylated seed oil (MSO), respectively. MSO was the adjuvant that provided the greatest enhancement of saflufenacil across all species tested. COC was the second-best adjuvant and provided control similar to MSO on many weed species. NIS provided the least enhancement of saflufenacil. These results are very similar to the proposed label dose of saflufenacil for burndown weed control, which will range from 25 to 100 g/ha with MSO or COC. We believe that such a dose would provide excellent burndown control of most broadleaf weed species that emerge in the fall in Nebraska.