Halosulfuron was recently registered as the second soil-applied herbicide for broadleaf weed control in Ontario dry beans, but does not provide an alternative mode of action. Sulfentrazone is used to control broadleaf weeds in soybean and other pulse crops, and its registration for Ontario dry beans would provide a different mode of action for broadleaf weed control. Five field studies were conducted over two years (2014, 2015) to determine if the spectrum of broadleaf weed control is improved by adding a half-rate of halosulfuron to sulfentrazone PRE, and to determine the tolerance of white bean to sulfentrazone (140 or 210 g ai ha -1), s-metolachlor (1050 g ai ha -1), and halosulfuron (17.5 g ai ha -1) applied alone and in combination. Crop injury was assessed at 2 and 4 weeks after crop emergence. Weed control was assessed at 4 and 8 weeks after herbicide application (WAA), and weed density and biomass were determined at 8 WAA. Seed moisture and yield were determined at harvest. Halosulfuron added to sulfentrazone improved the control of Ambrosia artemisiifolia and Sinapis arvensis. Sulfentrazone + s-metolachlor + halosulfuron caused up to 23% crop injury. Therefore, this study concludes that sulfentrazone + s-metolachlor + halosulfuron provides broad spectrum weed control, but is too injurious to white bean for registration in Ontario.
Dry edible beans (Phaseolus vulgaris L.) are a staple food that fit well in a typical Ontario crop rotation of corn, soybean and wheat. Several market classes of dry beans are grown in Ontario including cranberry, black, Dutch brown, kidney, small red Mexican, otebo, pinto, yellow eye and white (navy) bean. White bean is the predominant class of dry bean grown in Ontario, accounting for approximately 50% of production [
One of the most critical aspects of crop management for dry bean producers is weed control, as dry beans are poor competitors [
Sulfentrazone is a protoporphyrinogen oxidase IX (PPO) inhibitor herbicide in the aryl triazinone family and was recently registered Canada-wide for pre- emergence (PRE) application in chickpea (Cicer arientinum L.), soybean (Glycine max L.), sunflower (Helianthus annuus L.), flax (Linum usitatissimum L.) and field pea (Pisum sativum L.). Sulfentrazone is taken up by germinating weeds and is translocated to the shoot, where it inhibits the PPO enzyme and causes an excess of protoporphyrinogen IX. Various reactions occur in the cytoplasm resulting in the conversion of protoporphyrinogen IX to O+ radicals, which disrupt the cell membranes and cause loss of cell function [
In 2014, halosulfuron was available for the first time for use in Ontario. Halosulfuron is a sulfonyl urea herbicide, used in dry beans, corn (field, seed, sweet and popcorn-Zea mays L.) and various vegetable crops for broadleaf weed control. Halosulfuron controls common Ontario weed species such as common ragweed (Ambrosia artemisiifolia L.), common lambsquarters, wild mustard (Sinapis arvensis L.), redroot pigweed, flower-of-an-hour (Hibiscus trionum L.), and velvetleaf (Abutilon theophrasti L.) [
S-metolachlor is a chloroacetamide herbicide and is currently the only grass herbicide registered for PRE application in dry bean. S-metolachlor controls grass species such as Digitaria spp. (crabgrass), Echinochloa crusgalli (L.) Beauv. (barnyard grass), Panicum capilare L. (witchgrass), Panicum dichotomiflorum (L.) Michx. (fall panicum), and Setaria spp. [
Currently, halosulfuron and imazethapyr are the only soil-applied herbicides registered for broadleaf weed control in Ontario dry beans, and are both ALS inhibitor herbicides. As there are currently ten ALS inhibitor-resistant weed species in Ontario, dry bean growers will have difficulty controlling these weeds without another mode of action [
Five field studies were conducted over a two-year period (2014, 2015) at the University of Guelph Ridgetown Campus (Ridgetown) and Huron Research Station (Exeter) in Ontario, Canada. The 2014 site in Exeter was a clay loam soil of 31% sand, 42% silt and 27% clay, and had a pH of 7.8 and organic matter content of 4.3%. In 2015, the Exeter sites were both a loamy soil, with the first site consisting of 32% sand, 42% silt and 26% clay, pH of 7.7 and organic matter content of 3.2%, and the second site consisting of 35% sand, 43% silt, 22% clay, a pH of 7.6 and organic matter content of 3.6%. In Ridgetown, the soil at both sites was a sandy clay loam. The first site had a sand, silt, and clay content of 52%, 24%, and 24%, respectively, a pH of 7.3 and organic matter content of 4.3%. The second site had a sand, silt, and clay content of 46%, 27%, and 27%, respectively, a pH of 6.4 and an organic matter content of 3.7%. All sites were prepared by moldboard ploughing in the fall followed by two passes with an s-tine cultivator and rolling baskets in the spring. Plots were 3 m by 10 m in Exeter and 3 m by 8 m in Ridgetown. All plots were seeded with white bean variety “T9905” (obtained from Hensall District C0-operative, 1 Davidson Drive, Hensall, ON, N0M 1X0, Canada) at a rate of approximately 233,000 seeds ha−1, 4 to 5 cm deep in rows spaced 75 cm apart. Plots were not irrigated and were fertilized according to Ontario Ministry of Agriculture, Food and Rural Affairs field crops guidelines [
Experiments were arranged in a randomized complete block design with four replicates of thirteen treatments. An untreated weedy control and a weed-free control (sprayed with s-metolachlor (1050 g ai ha−1) + halosulfuron (35 g ai ha−1) PRE and maintained weed-free by hand-hoeing) were included in each replicate. Herbicide treatments included PRE applications of sulfentrazone (140 and 210 g ai ha−1), half the registered rate of halosulfuron (17.5 g ai ha−1), and s-meto- lachlor (1050 g ai ha−1) for grass control, used alone and in various combinations (
Crop injury was visually assessed at 2 and 4 weeks after crop emergence (WAE) by comparing the herbicide treatments to the weed-free control, and weed control was visually assessed at 4 and 8 weeks after herbicide application (WAA) by comparing the herbicide treatments to the weedy control. Herbicide treatments were given a score between 0% (no injury or weed control) to 100% (complete plant death). At 8 WAA, weed density and biomass were determined by counting the number of plants by species in 1 m2 per plot, followed by cutting
Treatment | Rate | Dry bean injury (%) | Seed moisture (%) | Yield (T ha−1) | |||||
---|---|---|---|---|---|---|---|---|---|
(g ai ha−1) | 2 WAE | 4 WAE | |||||||
Untreated Control | 0 | a | 0 | a | 17.5 | ab | 1.2 | g | |
Weed-free Control | 0 | a | 0 | a | 16.8 | a | 2.7 | a | |
S-metolachlor | 1050 | 2 | abc | 3 | abc | 17.2 | ab | 1.5 | defg |
Sulfentrazone | 140 | 5 | abc | 5 | abc | 17.3 | ab | 1.3 | fg |
Sulfentrazone | 210 | 10 | bcde | 10 | bcd | 17.4 | ab | 1.5 | efg |
Halosulfuron | 17.5 | 2 | ab | 1 | ab | 17.1 | ab | 1.8 | cdefg |
Sulfentrazone + s-metolachlor | 140 + 1050 | 9 | bcd | 10 | bcd | 17.3 | ab | 1.6 | defg |
Sulfentrazone + s-metolachlor | 210 + 1050 | 22 | e | 24 | d | 17.6 | b | 1.5 | efg |
Halosulfuron + s-metolachlor | 17.5 + 1050 | 3 | abc | 2 | ab | 17.0 | ab | 2.5 | ab |
Sulfentrazone + halosulfuron | 140 + 17.5 | 8 | bcd | 6 | abc | 17.0 | ab | 2.0 | bcde |
Sulfentrazone + halosulfuron | 210 + 17.5 | 17 | de | 15 | cd | 17.0 | ab | 1.8 | cdef |
Sulfentrazone + s-metolachlor + halosulfuron | 140 + 1050 + 17.5 | 12 | cde | 10 | bcd | 16.9 | ab | 2.3 | abc |
Sulfentrazone + s‑metolachlor + halosulfuron | 210 + 1050 + 17.5 | 23 | e | 22 | d | 16.9 | ab | 2.1 | abcd |
SE (±) | 0.06 | 0.06 | 0.01 | 0.01 |
aAbbreviations: PRE, pre-emergence; WAE, weeks after emergence. Means followed by the same letter within a column are not statistically different according to a Fisher’s Protected LSD test at α = 0.05. Data are averaged for years and locations.
the weeds at the soil surface, placing each species into a separate paper bag, drying in a kiln, and weighing the dry biomass. White bean seed moisture and yield (adjusted to 18% moisture) were determined at harvest.
Statistical Analysis Software (SAS) version 9.4 (SAS Institute Inc., NC) was used for the analysis. Data were partitioned into fixed and random effects to account for error. Treatments were deemed as fixed effects and their significance determined by the F-test. Replicate, environment, replicate within environment, and environment by treatment interaction were the random effects and their significance was determined using the Z-test. Various transformations of the data were applied using the UNIVARIATE procedure to test the assumptions of normality and homogeneity of the residuals. All transformations met the assumptions for the crop injury, weed control, seed moisture and yield data, therefore the arcsine square root transformation was selected for the analysis as it produced the least amount of error. Weed density and biomass data were transformed using a logarithmic transformation to meet the assumptions. An analysis of variance was performed on all data using the MIXED procedure and Fisher’s Protected LSD test (α = 0.05). Values were converted back to the original scale for presentation.
At 2 WAE, sulfentrazone (140 and 210 g ai ha−1) caused 5% and 10% injury in white bean, respectively (
Redroot pigweed and green pigweed (Amaranthus powelli S. Wats.) were the dominant pigweed species at the Exeter and Ridgetown locations, respectively, but were combined for analysis. All herbicides and herbicide combinations provided ≥89% control of pigweeds throughout the season (
At 4 WAA, sulfentrazone at 140 and 210 g ai ha−1 provided 19% and 24% control of common ragweed, respectively (
Treatment | Rate | Control (%) | Density 8 WAA | Biomass 8 WAA | |||||
---|---|---|---|---|---|---|---|---|---|
(g ai ha−1) | 4 WAA | 8 WAA | (plants m−2) | (g・m−2) | |||||
Untreated Control | 0 | b | 0 | b | 7.0 | b | 4.5 | b | |
Weed-free Control | 100 | a | 100 | a | 0.0 | a | 0.0 | a | |
S-metolachlor | 1050 | 89 | a | 99 | a | 0.4 | a | 0.5 | a |
Sulfentrazone | 140 | 100 | a | 100 | a | 0.3 | a | 0.3 | a |
Sulfentrazone | 210 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Halosulfuron | 17.5 | 91 | a | 90 | a | 0.6 | a | 0.4 | a |
Sulfentrazone + s-metolachlor | 140 + 1050 | 100 | a | 99 | a | 0.1 | a | 0.2 | a |
Sulfentrazone + s-metolachlor | 210 + 1050 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Halosulfuron + s-metolachlor | 17.5 + 1050 | 98 | a | 98 | a | 0.3 | a | 0.5 | a |
Sulfentrazone + halosulfuron | 140 + 17.5 | 99 | a | 99 | a | 0.1 | a | 0.1 | a |
Sulfentrazone + halosulfuron | 210 + 17.5 | 100 | a | 100 | a | 0.2 | a | 0.2 | a |
Sulfentrazone + s-metolachlor + halosulfuron | 140 + 1050 + 17.5 | 100 | a | 98 | a | 0.0 | a | 0.0 | a |
Sulfentrazone + s-metolachlor + halosulfuron | 210 + 1050 + 17.5 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
SE (±) | 0.09 | 0.09 | 0.17 | 0.23 |
aAbbreviations: PRE, pre-emergence; WAA, weeks after application. Means followed by the same letter within a column are not statistically different according to a Fisher’s Protected LSD test at α = 0.05. Data are averaged for years and locations.
Treatment | Rate | Control (%) | Density 8 WAA | Biomass 8 WAA | |||||
---|---|---|---|---|---|---|---|---|---|
(g ai ha−1) | 4 WAA | 8 WAA | (plants m−2) | (g・m−2) | |||||
Untreated Control | 0 | b | 0 | c | 7.5 | d | 11.1 | bcd | |
Weed-free Control | 100 | a | 100 | a | 0.2 | a | 0.3 | a | |
S-metolachlor | 1050 | 27 | b | 7 | c | 4.5 | bcd | 10.6 | bcd |
Sulfentrazone | 140 | 19 | b | 11 | c | 6.3 | cd | 15.9 | cd |
Sulfentrazone | 210 | 24 | b | 16 | c | 5.4 | bcd | 15.0 | cd |
Halosulfuron | 17.5 | 94 | a | 83 | a | 1.5 | abcd | 2.3 | abc |
Sulfentrazone + s-metolachlor | 140 + 1050 | 12 | b | 7 | c | 6.0 | cd | 15.4 | cd |
Sulfentrazone + s-metolachlor | 210 + 1050 | 26 | b | 18 | bc | 5.6 | bcd | 19.5 | d |
Halosulfuron + s-metolachlor | 17.5 + 1050 | 98 | a | 90 | a | 1.2 | abcd | 1.6 | ab |
Sulfentrazone + halosulfuron | 140 + 17.5 | 86 | a | 75 | ab | 1.3 | abcd | 2.9 | abcd |
Sulfentrazone + halosulfuron | 210 + 17.5 | 90 | a | 77 | a | 1.7 | abcd | 1.8 | abc |
Sulfentrazone + s-metolachlor + halosulfuron | 140 + 1050 + 17.5 | 94 | a | 90 | a | 0.7 | ab | 0.7 | a |
Sulfentrazone + s-metolachlor + halosulfuron | 210 + 1050 + 17.5 | 98 | a | 94 | a | 0.8 | abc | 1.4 | ab |
SE (±) | 0.16 | 0.18 | 0.54 | 0.65 |
aAbbreviations: PRE, pre-emergence; WAA, weeks after application. Means followed by the same letter within a column are not statistically different according to a Fisher’s Protected LSD test at α = 0.05. Data are averaged for years and locations.
up to 97% control of common ragweed in pumpkin with 18 g ai ha−1 halosulfuron. Sulfentrazone (140 and 210 g ai ha−1) + s-metolachlor provided up to 26% control, and was not improved compared to either herbicide applied alone. In contrast, sulfentrazone (140 and 210 g ai ha−1) + halosulfuron provided 86% and 90% control, respectively, which was equivalent to the weed-free control and an improvement compared to sulfentrazone applied alone. Similarly, sulfentrazone (140 and 210 g ai ha−1) + s-metolachlor + halosulfuron provided 94% to 98% control and were equivalent to the weed-free control. Soltani et al. [
Sulfentrazone (140 and 210 g ai ha−1) provided 100% control of common lambsquarters at 4 and 8 WAA (
Treatment | Rate | Control (%) | Density 8 WAA | Biomass 8 WAA | |||||
---|---|---|---|---|---|---|---|---|---|
(g ai ha−1) | 4 WAA | 8 WAA | (plants m−2) | (g・m−2) | |||||
Untreated Control | 0 | b | 0 | c | 13.9 | d | 7.1 | b | |
Weed-free Control | 100 | a | 100 | a | 0.2 | a | 0.2 | a | |
S-metolachlor | 1050 | 7 | b | 16 | c | 4.6 | c | 5.8 | b |
Sulfentrazone | 140 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Sulfentrazone | 210 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Halosulfuron | 17.5 | 87 | a | 97 | ab | 2.5 | bc | 0.4 | a |
Sulfentrazone + s-metolachlor | 140 + 1050 | 100 | a | 99 | ab | 0.0 | a | 0.0 | a |
Sulfentrazone + s-metolachlor | 210 + 1050 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Halosulfuron + s-metolachlor | 17.5 + 1050 | 91 | a | 76 | b | 1.0 | ab | 0.6 | a |
Sulfentrazone + halosulfuron | 140 + 17.5 | 99 | a | 99 | ab | 0.1 | a | 0.2 | a |
Sulfentrazone + halosulfuron | 210 + 17.5 | 100 | a | 99 | ab | 0.0 | a | 0.0 | a |
Sulfentrazone + s-metolachlor + halosulfuron | 140 + 1050 + 17.5 | 100 | a | 100 | ab | 0.0 | a | 0.0 | a |
Sulfentrazone + s-metolachlor + halosulfuron | 210 + 1050 + 17.5 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
SE (±) | 0.09 | 0.11 | 0.17 | 0.17 |
aAbbreviations: PRE, pre-emergence; WAA, weeks after application. Means followed by the same letter within a column are not statistically different according to a Fisher’s Protected LSD test at α = 0.05. Data are averaged for years and locations.
reduced lambsquarters biomass by 100%, 100%, 18% and 94%, respectively. Sulfentrazone + s-metolachlor provided a 100% reduction, sulfentrazone + halosulfuron provided 97 to 100% reduction in biomass, and sulfentrazone (140 and 210 g ai ha−1) + s-metolachlor + halosulfuron reduced biomass by 100%. Sulfentrazone has shown excellent control of common lambsquarters when used alone and in a tank mix [
Sulfentrazone (140 and 210 g ai ha−1), s-metolachlor, and halosulfuron provided 50%, 48%, 20% and 100% control of wild mustard, respectively, at 4 WAA (
Treatment | Rate | Control (%) | Density 8 WAA | Biomass 8 WAA | |||||
---|---|---|---|---|---|---|---|---|---|
(g ai ha−1) | 4 WAA | 8 WAA | (plants m−2) | (g・m−2) | |||||
Untreated Control | 0 | e | 0 | c | 31.0 | c | 93.6 | b | |
Weed-free Control | 100 | a | 100 | a | 0.0 | a | 0.0 | a | |
S-metolachlor | 1050 | 20 | d | 2 | bc | 15.9 | bc | 51.8 | b |
Sulfentrazone | 140 | 50 | cd | 5 | bc | 10.3 | bc | 37.1 | b |
Sulfentrazone | 210 | 48 | cd | 12 | bc | 10.3 | bc | 32.1 | b |
Halosulfuron | 17.5 | 100 | ab | 100 | a | 0.0 | a | 0.0 | a |
Sulfentrazone + s-metolachlor | 140 + 1050 | 54 | c | 1 | bc | 10.5 | bc | 51.7 | b |
Sulfentrazone + s-metolachlor | 210 + 1050 | 87 | b | 20 | b | 5.3 | b | 14.8 | b |
Halosulfuron + s-metolachlor | 17.5 + 1050 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Sulfentrazone + halosulfuron | 140 + 17.5 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Sulfentrazone + halosulfuron | 210 + 17.5 | 100 | a | 100 | a | 0.1 | a | 0.0 | a |
Sulfentrazone + s-metolachlor + halosulfuron | 140 + 1050 + 17.5 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
Sulfentrazone + s-metolachlor + halosulfuron | 210 + 1050 + 17.5 | 100 | a | 100 | a | 0.0 | a | 0.0 | a |
SE (±) | 0.07 | 0.09 | 0.28 | 0.45 |
aAbbreviations: PRE, pre-emergence; WAA, weeks after application. Means followed by the same letter within a column are not statistically different according to a Fisher’s Protected LSD test at α = 0.05. Data are averaged for years and locations.
weedy control. Sulfentrazone (140 g ai ha−1) + s-metolachlor also did not reduce density relative to the control, but sulfentrazone (210 g ai ha−1) + s-metolachlor significantly reduced density by 83%. Similarly, sulfentrazone reduced wild mustard biomass by up to 66%, s-metolachlor reduced biomass by 45%, and sulfentrazone + s-metolachlor reduced biomass by up to 84%, but none were different from the weedy control. In contrast, halosulfuron and all co-applications containing halosulfuron reduced density and biomass equivalent to the weed-free control.
At 4 WAA, sulfentrazone (140 and 210 g ai ha−1) provided 68% and 84% control of green foxtail (Setaria viridis (L.) Beauv), respectively, s-metolachlor provided 99% control and halosulfuron provided 31% control (
Treatment | Rate | Control (%) | Density 8 WAA | Biomass 8 WAA | |||||
---|---|---|---|---|---|---|---|---|---|
(g ai ha−1) | 4 WAA | 8 WAA | (plants m−2) | (g・m−2) | |||||
Untreated Control | 0 | d | 0 | f | 87.3 | f | 42.4 | g | |
Weed-free Control | 100 | a | 100 | a | 0.0 | a | 0.0 | a | |
S-metolachlor | 1050 | 99 | a | 99 | ab | 1.8 | abc | 0.7 | ab |
Sulfentrazone | 140 | 68 | b | 45 | de | 20.1 | def | 7.8 | def |
Sulfentrazone | 210 | 84 | b | 80 | bcd | 8.3 | bcde | 4.4 | bcde |
Halosulfuron | 17.5 | 31 | c | 11 | ef | 48.7 | ef | 20.3 | fg |
Sulfentrazone + s-metolachlor | 140 + 1050 | 99 | a | 98 | ab | 1.6 | abc | 0.6 | ab |
Sulfentrazone + s-metolachlor | 210 + 1050 | 99 | a | 99 | ab | 0.8 | ab | 0.4 | a |
Halosulfuron + s-metolachlor | 17.5 + 1050 | 98 | a | 96 | ab | 3.5 | abcd | 1.5 | abcd |
Sulfentrazone + halosulfuron | 140 + 17.5 | 67 | b | 42 | de | 26.3 | def | 10.8 | efg |
Sulfentrazone + halosulfuron | 210 + 17.5 | 85 | b | 63 | cd | 11.9 | cde | 5.7 | cdef |
Sulfentrazone + s-metolachlor + halosulfuron | 140 + 1050 + 17.5 | 98 | a | 95 | abc | 1.1 | abc | 0.8 | ab |
Sulfentrazone + s-metolachlor + halosulfuron | 210 + 1050 + 17.5 | 99 | a | 98 | ab | 1.3 | abc | 0.8 | abc |
SE (±) | 0.07 | 0.12 | 0.56 | 0.49 |
aAbbreviations: PRE, pre-emergence; WAA, weeks after application. Means followed by the same letter within a column are not statistically different according to a Fisher’s Protected LSD test at α = 0.05. Data are averaged for years and locations.
relative to sulfentrazone on its own, but did provide control relative to the weedy control. Sulfentrazone (140 and 210 g ai ha−1) + s-metolachlor + halosulfuron provided 95% to 98% control and were equivalent to the weed-free control. Other studies have shown improved control of foxtail species when either sulfentrazone or halosulfuron were tank mixed with a grass herbicide [
Seed moisture at harvest ranged between 16.8% and 17.6% (
In this study, sulfentrazone applied PRE provided excellent control of redroot/ green pigweed and common lambsquarters. When a low rate of halosulfuron was added to sulfentrazone, the spectrum of broadleaf weed control was improved. Sulfentrazone + halosulfuron provided good to excellent control of pigweeds, common lambsquarters, common ragweed, and wild mustard. Sulfentrazone + s-metolachlor + halosulfuron also provided excellent control of these species as well as green foxtail, but did not have an adequate margin of crop safety, therefore this study does not support the use of a tank mix of sulfentrazone + s-metolachlor + halosulfuron in Ontario white bean. However, this tank mix does provide broad spectrum weed control, and should be examined in other market classes of dry bean to determine their tolerance to the co-applica- tion of these three herbicides.
Taziar, A.N., Soltani, N., Shropshire, C., Robinson, D.E., Long, M., Gillard, C.L. and Sikkema, P.H. (2017) Sulfentrazone plus a Low Rate of Halosulfuron for Weed Control in White Bean (Phaseolus vulgaris L.). Agricultural Sciences, 8, 227-238. https://doi.org/10.4236/as.2017.83016