A total of twelve field trials (6 with kidney bean and 6 with white bean) were conducted over a three-year period (2010 to 2012) at various locations in Ontario to evaluate the tolerance of kidney and white bean to im...A total of twelve field trials (6 with kidney bean and 6 with white bean) were conducted over a three-year period (2010 to 2012) at various locations in Ontario to evaluate the tolerance of kidney and white bean to imazethapyr applied preplant incorporated (PPI), preemergence (PRE), and postemergence (POST) at 37.5, 75 and 150 g·ai·ha-1. Imazethapyr applied PPI or PRE in kidney or white bean caused 0%-1%, 0%-4%, and 0%-9% injury at 1, 2, and 4 weeks after application (WAA), respectively. However, the injury was transient and had no adverse effect on shoot dry weight, height, seed moisture content, and yield of kidney or white bean except for shoot dry weight which was reduced 32% with imazethapyr applied PPI compared to the weed free control in white bean. Imazethapyr applied POST in kidney or white bean caused as much as 17%, 18%, and 11% injury at 1, 2, and 4 WAA, respectively. There was no adverse effect on shoot dry weight, height, seed moisture content, and yield of kidney or white bean except for imazethapyr applied POST which increased seed moisture content 1.9% compared to the weed free control in white bean. Based on these results, there is an adequate margin of crop safety in dry bean to imazethapyr applied PPI or PRE at 37.5 or 75 g·ai·ha-1 in kidney and white beans. However, there is not an adequate margin of crop safety for imazethapyr applied POST at rates higher than 37.5 g·ai·ha-1 in kidney and white bean.展开更多
There is limited information available on the effect of biostimulants such as Crop Booster or RR SoyBooster on corn, oats and winter wheat under Ontario environmental conditions. A total of 37 field experiments were c...There is limited information available on the effect of biostimulants such as Crop Booster or RR SoyBooster on corn, oats and winter wheat under Ontario environmental conditions. A total of 37 field experiments were conducted in corn, oats and winter wheat at two locations (Ridgetown and Exeter, Ontario, Canada) to evaluate the effect of Crop Booster or RR SoyBooster on crop injury, weed control and yield. The addition of Crop Booster to glyphosate did not affect weed control or corn yield except at 4 weeks after herbicide application (WAA) when control of pigweed species was increased by 1% and at 4 and 8 WAA when control of common lambsquarters was reduced by 1%. The addition of RR SoyBooster to glyphosate did not affect crop injury, weed control or corn yield. The addition of Crop Booster to glyphosate + topramezone + atrazine did not affect crop injury, weed control or corn yield except at 4 WAA when control of common ragweed was reduced by 1%. The tank mix of Crop Booster with glyphosate + thiencarbazone-methyl did not affect crop injury, weed control or corn yield except at 4 WAA when control of green foxtail and annual grasses were reduced by 2% and 1%, respectively. The addition of Crop Booster to bromoxynil/ MCPA had no significant effect on crop injury, weed control or yield of oats or winter wheat.展开更多
New herbicide options are needed for postemergence (POST) broadleaf weed control in adzuki bean. A field study, of five experiments, was conducted over a three-year period (2014, 2015, 2016) in Ontario to evaluate the...New herbicide options are needed for postemergence (POST) broadleaf weed control in adzuki bean. A field study, of five experiments, was conducted over a three-year period (2014, 2015, 2016) in Ontario to evaluate the tolerance of adzuki bean to the POST application of acifluorfen (600 and 1200 g·ai·ha-1), fomesafen (240 and 480 g·ai·ha-1), bentazon (1080 and 2160 g·ai·ha-1), imazethapyr (100 and 200 g·ai·ha-1) and halosulfuron-methyl (75 and 150 g·ai·ha-1). Acifluorfen and fomesafen applied POST caused as much as 12% visible injury at the 1X rate and 20% visible injury at the 2X rate but had no adverse effect on adzuki bean population, shoot dry weight, height, maturity or yield. Bentazon caused as much as 23% visible injury at 1080 g·ai·ha-1 and 28% visible injury at 2160 g·ai·ha-1 but caused no adverse effect on adzuki bean population, shoot dry weight, height, maturity or yield at either rate, except at 2160 g·ai·ha-1 which reduced shoot dry weight 20% and height 12%. Imazethapyr caused as much as 22% visible injury at 100 g·ai·ha-1 and 34% visible injury at 200 g·ai·ha-1 but caused no adverse effect on adzuki bean population, shoot dry weight, height, maturity or yield at either rate except at 200 g·ai·ha-1 which delayed maturity slightly. Halosulfuron-methyl caused as much as 65% visible injury and reduced shoot dry weight, height and yield 64%, 41%, and 28%, respectively. This research concludes that acfluorfen, fomesafen, bentazon, imazethapyr and halosulfuron at the rates evaluated can cause the significant injury in adzuki bean.展开更多
Glyphosate resistant (GR) Canada fleabane has spread quickly across southwestern Ontario and new strategies for the control of this competitive weed must be developed especially in no-tillage crops. A premix of 2,4-D ...Glyphosate resistant (GR) Canada fleabane has spread quickly across southwestern Ontario and new strategies for the control of this competitive weed must be developed especially in no-tillage crops. A premix of 2,4-D choline and glyphosate dimethylamine (DMA) has been developed for application on tolerant corn, soybean and cotton crops that provides an option for the control of this problematic GR weed. The objective of this research was to determine the required dose needed to effectively control GR Canada fleabane at different size categories in field and greenhouse experiments. In the field experiments, nine rates of 2,4-D choline/glyphosate DMA (53.8 to 13,760 g·ae·ha-1) were applied to GR Canada fleabane that were 10 cm in diameter/tall, 20 cm tall or 30 cm tall. Similarly, in the greenhouse, seven rates of 2,4-D choline/glyphosate DMA (0 to 3440 g·ae·ha-1) were applied to 10, 20 and 30 cm tall GR Canada fleabane plants. The three different size classes of GR Canada fleabane responded similarly to 2,4-D choline/glyphosate DMA in the field experiment. In the greenhouse there were some differences in control for the three size classes of GR Canada fleabane with 2,4-D choline/glyphosate DMA;the 20 and 30 cm tall plants required similar rates to provide equivalent control, but the 10 cm plants required a lower rate. In all situations, greater than 1720 g·ae·ha-1 of 2,4-D choline/glyphosate DMA was required to provide 95% control of 10, 20 and 30 cm tall Canada fleabane in greenhouse (35 DAA) and field experiments (8 WAA), respectively.展开更多
Tolerance of carrot and red beet to s-metolachlor at three application timings—pre-emergence to crop (PRE), early postemergence (crop at two to four leaf stage-EPOST), and late postemergence (crop at five to seven le...Tolerance of carrot and red beet to s-metolachlor at three application timings—pre-emergence to crop (PRE), early postemergence (crop at two to four leaf stage-EPOST), and late postemergence (crop at five to seven leaf stage-LPOST) —was determined from 2008 to 2010. LPOST applications of s-metolachlor reduced carrot above ground plant dry weight, marketable yield and grower payment, but did not affect carrot length. PRE and LPOST applications of s-metolachlor reduced red beet above ground plant dry weight, total marketable yield, yield of No. 2 and No. 3 red beet, and grower payment. Our findings indicate that while carrot may be tolerant to PRE applications of s-metolachlor, applications made after the 5 leaf stage reduced plant dry weight enough to impact marketable yield and grower payment. In red beet, the potential reduction in growth, yield and grade would not justify the utility of a PRE or LPOST applica- tion timing.展开更多
A population of common ragweed in Ontario was confirmed to be resistant to glyphosate in 2011. Group 2 [acetolactate synthase (ALS) inhibitors] resistant common ragweed was first confirmed in Ontario in 2000. Previous...A population of common ragweed in Ontario was confirmed to be resistant to glyphosate in 2011. Group 2 [acetolactate synthase (ALS) inhibitors] resistant common ragweed was first confirmed in Ontario in 2000. Previously, glyphosate provided excellent control of common ragweed in glyphosate resistant soybean but with the confirmation of glyphosate resistant (GR) common ragweed, alternative herbicides need to be evaluated. Eight field trials with preplant herbicides were completed over two years (2013 and 2014) in fields with confirmed GR common ragweed. Tank-mixes of glyphosate and linuron or metribuzin provided 88% - 99% and 86% - 98% control 4 weeks after application (WAA) and 80% - 92% and 80% - 95% control 8 WAA, respectively. However, these herbicides also had among the highest environmental impact of the herbicides tested. Based on the results of these studies, GR common ragweed can be controlled with residual herbicides when applied preemergence in soybean. Currently, there are no post emergence herbicides that provide adequate control of GR common ragweed, therefore, preemergence herbicides with residual are essential for full season control.展开更多
There are a limited number of postemergence (POST) herbicides available for weed management in mung bean production in Ontario. Five field studies were conducted in 2010, 2011 and 2012 near Exeter, Ontario and in 2011...There are a limited number of postemergence (POST) herbicides available for weed management in mung bean production in Ontario. Five field studies were conducted in 2010, 2011 and 2012 near Exeter, Ontario and in 2011 and 2012 near Ridgetown, Ontario to determine the tolerance of mung bean to fomesafen, bentazon, bentazon + fomesafen and halosulfuron applied POST at the 1X and 2X proposed manufacturer’s recommended rate. Bentazon caused 5%-29%, 4%-31%, and 2%-18% injury, fomesafen caused 3%-17%, 1%-7%, and 0%-6% injury, bentazon + fomesafen caused 6%-40%, 4%-37%, and 1%-20% injury, and halosulfuron caused 13%-65%, 8%-75%, and 5%-47% injury in mung bean at 1, 2, and 4 weeks after treatment (WAT), respectively. At Exeter, fomesafen had no adverse effect on height of mung bean but bentazon, bentazon + fomesafen and halosulfuron decreased mung bean height as much as 5% compared to the untreated control. At Ridgetown, there was no decrease in mung bean height due to the herbicides applied. Fomesafen had no adverse effect on shoot dry weight of mung bean but bentazon, bentazon + fomesafen and halosulfuron decreased shoot dry weight of mung beans as much as 43%, 47%, and 57%, respectively. Fomesafen, bentazon, bentazon + fomesafen and halosulfuron had no adverse effect on the seed moisture content and seed yield of mung bean with the exception of halosulfuron applied POST at 70 g ai ha-1 which increased seed moisture content 0.4% at Exeter and 1.4% at Ridgetown and decreased yield 16% at Exeter compared to the untreated control. Based on these results, there is not an adequate margin of crop safety for bentazon, bentazon + fomesafen and?halosulfuron applied POST in mung bean. However, there is potential for fomesafen applied POST at the proposed manufacturer’s rate of 240 g ai ha-1 in mung bean production.展开更多
Only one herbicide mode of action (ALS inhibitor) is currently available to Ontario dry bean producers for soil-applied broadleaf weed control. Four field studies were conducted over two years (2014, 2015) to examine ...Only one herbicide mode of action (ALS inhibitor) is currently available to Ontario dry bean producers for soil-applied broadleaf weed control. Four field studies were conducted over two years (2014, 2015) to examine the tolerance of four market classes of dry beans to sulfentrazone (210 and 420 g·ai·ha<sup>-1</sup>) and pyroxasulfone (100 and 200 g·ai·ha<sup>-1</sup>) applied alone and in combination. The registration of these two herbicides would provide Ontario dry bean producers with two additional modes of action for broadleaf weed control. Pyroxasulfone caused up to 23%, 6%, 7% and 10% injury in adzuki, kidney, small red Mexican and white bean, respectively;sulfentrazone caused up to 51%, 12%, 15% and 44% injury and the combination caused up to 90%, 23%, 29% and 62% injury, respectively. Kidney and small red Mexican bean density, height, seed moisture content and yield were not affected. Pyroxasulfone (200 g·ai·ha<sup>-1</sup>) + sulfentrazone (420 g·ai·ha<sup>-1</sup>) reduced adzuki and white bean density, shoot dry weight, height and yield. This study concludes that pyroxasulfone (100 g·ai·ha<sup>-1</sup>) + sulfentrazone (210 g·ai·ha<sup>-1</sup>) applied PRE can be safely used to control weeds in Ontario kidney and small red Mexican bean production.展开更多
The objective of this research was to evaluate the efficacy of various pre-emergence (PRE) and post-emergence (POST) herbicides for the control of volunteer adzuki bean (Vigna angularis (Willd.) Ohwi & Ohashi) in ...The objective of this research was to evaluate the efficacy of various pre-emergence (PRE) and post-emergence (POST) herbicides for the control of volunteer adzuki bean (Vigna angularis (Willd.) Ohwi & Ohashi) in soybean (Glycine max L.). Trials were conducted at two locations in 2005, 2006, 2007, and 2009. Experiments were arranged in a randomized complete block design with either five PRE or nine POST herbicides. Volunteer adzuki bean interference in soybean resulted in yield loss of up to 25%. Cloransulam-methyl, linuron, metribuzin, flumetsulam, and imazethapyr applied PRE provided up to 6, 24, 14, 8, and 0% control, respectively at 8 weeks after emergence (WAE), while acifluorfen, fomesafen, bentazon, thifensulfuron-methyl, cloransulam-methyl, imazethapyr, and imazethapyr plus bentazon applied POST provided 2, 2, 5, 34, 6, 4, and 12% control, respectively at 8 weeks after application (WAA). Generally, with the aforementioned herbicides, soybean yield was equivalent to the weedy control and soybean grain contamination with adzuki bean seed was consistently above the 1% maximum threshold. Chlorimuron-ethyl and glyphosate applied POST provided up to 84 and 94% visual control at 8 WAA, respectively, decreased adzuki bean density, biomass, and seed production, and generally decreased soybean contamination with adzuki bean below the 1% threshold. The only herbicides evaluated in this study that controlled volunteer adzuki bean in soybean were chlorimuron-ethyl (9 g ai.ha-1) and glyphosate (900 g ai.ha-1) applied POST. All the other PRE and POST herbicides evaluated did not provide adequate control of volunteer adzuki bean in soybean.展开更多
There are a limited number of herbicides registered for weed management in white bean production in Ontario, Canada. Five field experiments were completed in Ontario from 2016 to 2018 to compare the efficacy of triflu...There are a limited number of herbicides registered for weed management in white bean production in Ontario, Canada. Five field experiments were completed in Ontario from 2016 to 2018 to compare the efficacy of trifluralin and ethalfluralin applied alone and in combination with halosulfuron, applied preplant incorporated (PPI), for weed control efficacy and white bean tolerance and seed yield. At 2 and 4 WAE, there was no white bean injury from the herbicide treatments evaluated. Trifluralin applied PPI provided up to 32%, 99%, 13%, 99%, 27%, 99% and 99% control of velvetleaf, redroot pigweed, common ragweed, common lambsquarters, wild mustard, barnyardgrass and green foxtail, respectively. Trifluralin and ethalfluralin provide similar control of velvetleaf, redroot pigweed, barnyardgrass and green foxtail control, however, ethalfluralin is slightly more efficacious on common ragweed, common lambsquarters and wild mustard. Halosulfuron (35 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>), applied PPI, provided as much as 76%, 98%, 96%, 96%, 100%, 19% and 23% control of velvetleaf, redroot pigweed, common ragweed, common lambsquarters, wild mustard, barnyardgrass and green foxtail, respectively. Trifluralin (600 or 1155 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>) + halosulfuron (35 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>), applied PPI, provided up to 88%, 100%, 98%, 100%, 100%, 99% and 98% control of velvetleaf, redroot pigweed, common ragweed, common lambsquarters, wild mustard, barnyardgrass and green foxtail, respectively. Ethalfluralin (810 or 1080 ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>) + halosulfuron (35 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>) provided similar control. Weed interference decreased white bean seed yield 44% - 45% with trifluralin, 30% - 41% with ethalfluralin and 34% with halosulfuron. However, decreased weed interference with trifluralin and ethalfluralin applied in combination with halosulfuron resulted white bean seed yield that was similar to the weed-free control. Trifluralin or ethalfluralin co-applied with halosulfuron can be safely used in white bean production for the control of common annual grass and broadleaf weeds in Ontario.展开更多
Five field trials were conducted over a two-year period (2013, 2014) to determine the control of glyphosate-resistant (GR) giant ragweed with isoxaflutole (IFT) and metribuzin (MTZ) applied alone and in combination. T...Five field trials were conducted over a two-year period (2013, 2014) to determine the control of glyphosate-resistant (GR) giant ragweed with isoxaflutole (IFT) and metribuzin (MTZ) applied alone and in combination. Treatments were designed to assess the dose response of an IFT plus MTZ tank-mix as well as each chemical applied alone to classify the response using Flint’s adaptation of Colby’s equation. Two factor factorial experiments were performed in the growth room to ascertain the response of IFT versus glyphosate, IFT versus MTZ, and IFT plus MTZ versus glyphosate on single plants. Field experiments evaluated the control of GR giant ragweed with IFT plus MTZ in tank-mix in a 1:4 ratio. The rate of IFT plus MTZ for 80% control of GR giant ragweed at 4 and 8 weeks after application (WAA) was 518 (104 g a.i. ha<sup>-1</sup> IFT + 414 g a.i. ha<sup>-1</sup> MTZ) and 631 g a.i. ha<sup>-1</sup> (126 g a.i. ha<sup>-1</sup> IFT + 505 g a.i. ha<sup>-1</sup> MTZ), respectively. A rate of 668 and 467 g a.i. ha<sup>-1</sup> was required to reduce GR giant ragweed density and biomass by 80%, respectively. Field experiments evaluating the control of GR giant ragweed with tank-mixes of IFT plus MTZ, where glyphosate was a constant tank-mix partner, were mostly synergistic. However, the low tank-mix rate (52.5 + 210 g a.i. ha<sup>-1</sup>) had an additive response for GR giant ragweed biomass reduction. When tested in the greenhouse and growth room, glyphosate susceptible (GS) giant ragweed showed some antagonism with glyphosate and isoxaflutole tank-mixes at rates less than commercial field rates. GR giant ragweed showed an additive response across all treatments in the growth room. Greenhouse experiments evaluating IFT versus MTZ and IFT plus MTZ versus glyphosate revealed all tank-mix treatments to be synergistic at 2 WAA.展开更多
The use of glyphosate-resistant corn has facilitated a shift from a reliance on preemergence residual herbicides to postemergence (POST) herbicides, and in some cases exclusively glyphosate. Glyphosate is a non-select...The use of glyphosate-resistant corn has facilitated a shift from a reliance on preemergence residual herbicides to postemergence (POST) herbicides, and in some cases exclusively glyphosate. Glyphosate is a non-selective herbicide that is relatively slow-acting, which may allow weeds to continue to compete with corn after application and potentially decrease crop yield. The addition of several POST corn herbicides, with some residual control, to an early-season glyphosate application was examined to determine if the tankmix combination would improve the speed of weed control compared to glyphosate applied alone. Seven field trials were conducted over three years (2009, 2010 and 2011) near Ridgetown and Exeter, Ontario. The control of common ragweed was improved 3 days after application (DAA) with three POST glyphosate tankmixes compared to glyphosate alone. However control was still less than 55%. Depending on the weed species examined, at 28 DAA two of the glyphosate tankmix treatments tested provided better common ragweed, common lambsquarters, or green foxtail control than glyphosate alone. Treatments providing better weed control at 28 DAA also typically decreased weed density compared to glyphosate alone.展开更多
Glyphosate-resistant (GR) giant ragweed has recently been identified in southwestern Ontario and has the potential to be a significant problem for regional corn producers. Eight field trials [four with preplant (PP) a...Glyphosate-resistant (GR) giant ragweed has recently been identified in southwestern Ontario and has the potential to be a significant problem for regional corn producers. Eight field trials [four with preplant (PP) and four with postemergence (POST) herbicides] were conducted from 2013 to 2014 on various Ontario farms infested with GR giant ragweed to determine the efficacy of PP and POST tank-mixes in corn. Glyphosate tank-mixed with atrazine, dicamba, dicamba/atrazine, mesotrione plus atrazine, flumetsulam, isoxaflutole plus atrazine, saflufenacil/dimethenamid-P, S-metolachlor/atrazine and rimsulfuron applied PP provided up to 54%, 95%, 93%, 95%, 40%, 89%, 91%, 50% and 93% control of GR giant ragweed and reduced dry weight 69%, 100%, 99%, 100%, 30%, 92%, 98%, 66% and 99%, respectively. POST application of glyphosate alone and tank-mixed with 2,4-D ester, atrazine, dicamba, dicamba/diflufenzopyr, dicamba/atrazine, bromoxynil plus atrazine, prosulfuron plus dicamba, mesotrione plus atrazine, topramezone plus atrazine, tembotrione/thiencarbazone-methyl and glufosinate provided up to 31%, 84%, 39%, 94%, 89%, 86%, 83%, 78%, 72%, 43%, 63% and 58% GR giant ragweed and reduced dry weight 55%, 99%, 72%, 99%, 99%, 98%, 96%, 96%, 93%, 89%, 91% and 95%, respectively. In general, PP control of GR giant ragweed was greater than POST applied herbicides evaluated. Based on these results, glyphosate tank-mixes containing dicamba or mesotrione plus atrazine applied PP, and dicamba applied POST will provide the most consistent control of GR giant ragweed in corn.展开更多
Twenty-two field experiments (six maize (Zea mays L.) and five soybean [Glycine max (L.) Merr.] using low glyphosate doses to assess weed control and six maize and five soybean using high glyphosate doses to assess to...Twenty-two field experiments (six maize (Zea mays L.) and five soybean [Glycine max (L.) Merr.] using low glyphosate doses to assess weed control and six maize and five soybean using high glyphosate doses to assess tolerance) were conducted from 2010 to 2012 at two locations in southern Ontario, Canada to compare the commercially available glyphosate formulations of Roundup Weather MAX?, Clearout?41 Plus, and Wise Up? (WeatherMAX, Clearout, and WiseUp, respectively). Inmaize and soybean, control of velvetleaf, pigweed species, common lambs quarters, and green foxtail 4 weeks after treatment (WAT) using 900 g·ae·ha-1 ranged from at least 85% to 99%, regardless of formulation. By 8 WAT with 900 g·ae·ha-1, control of these weeds generally declined, but still ranged from 82% to 97% across all formulations. At harvest, maize yields were similar to the weed-free control for 900 g·ae·ha-1 of glyphosate as WeatherMAX and Clearout;however, reduced weed control with WiseUp resulted in an 8.8% yield loss. For soybean, yields were similar to the weed-free control, regardless of formulation or dose. In the tolerance experiments, 2.1% and 2.8% injury was observed 4 WAT for maize treated with 3600 g·ae·ha-1 of glyphosate as WeatherMAX and WiseUp, respectively. However, maize yields were unaffected by glyphosate formulation or dose. In soybean, visible injury of 8.5%, 4.5%, and 3.7% was observed 1 WAT with 5400 g·ae·ha-1 of glyphosate as WeatherMAX, WiseUp, and Clearout, respectively;by 8 WAT, visible injury was similar to the untreated control, regardless of formulation or dose. The early injury from 5400 g·ae·ha-1 of glyphosate resulted in 8.5%, 4.6%, and 5.5% yield loss for the WeatherMAX, WiseUp, and Clearout formulations, respectively.展开更多
Fifteen field experiments were conducted from 2009 to 2012 in Ontario, Canada and Michigan, USA to determine the tolerance of corn (Zea mays L.) to early (spike or 1- to 2-leaf stage) or late (8- or 10-leaf stage) app...Fifteen field experiments were conducted from 2009 to 2012 in Ontario, Canada and Michigan, USA to determine the tolerance of corn (Zea mays L.) to early (spike or 1- to 2-leaf stage) or late (8- or 10-leaf stage) applications of 900, 1800, 3600, or 7200 g·ae·ha-1 of glyphosate. Postemergence applications were evaluated for corn injury, cob length and deformity, crop moisture at harvest, and yield in the absence of weed competition. In the early application experiment, no visible injury was detected with applications of up to 3600 g·ae·ha-1;however, 1.4% injury was observed 4 weeks after treatment (WAT) when 7200 g·ae·ha-1 was applied to 1- to 2-leaf stage corn. Yet by harvest, the observed injury was transient as yields were similar to the untreated control regardless of glyphosate dose or timing. In the late application experiment, visible injury tended to increase with glyphosate dose. In addition, for corn treated with 7200 g·ae·ha-1 at the 10-leaf stage, injury increased over time as 6%, 11%, and 12% injury was observed 1, 2, and 4 WAT, respectively. Similar to the visible injury of vegetative tissue, cob deformity and reductions in yield tended to increase with glyphosate dose, but this response varied and the data were pooled into two environment groups. For example, in one environment group, corn treated with 7200 g·ae·ha-1 at the 8- and 10-leaf stage had a 9.5% and 14.6% reduction in yield, respectively. Whereas in another environment group, corn yields were similar to the untreated control regardless of glyphosate dose or timing. This research demonstrated that commercially available corn hybrids have tolerance to glyphosate at doses greater than what has been previously published or could reasonably be expected during spray overlaps in a field.展开更多
Giant ragweed was the first glyphosate resistant weed identified in Canada. It is a very competetive weed in row crop production and has been found to drastically reduce yields of soybean;therefore, control of this co...Giant ragweed was the first glyphosate resistant weed identified in Canada. It is a very competetive weed in row crop production and has been found to drastically reduce yields of soybean;therefore, control of this competitive weed is essential. The objective of this study was to determine effective control options for glyphosate resistant giant ragweed in soybean with herbicides applied preplant. Eighteen herbicide combinations were evaluated in field studies conducted in 2011 and 2012 at five locations with confirmed glyphosate resistant giant ragweed. Glyphosate plus 2,4-D ester or amitrole provided the best control of glyphosate resistant giant ragweed 4 WAA. Glyphosate plus 2,4-D ester provided 98 to 99% control and was equivalent to the weed free check at all locations. Glyphosate plus amitrole provided 90% to 93% control and was equivalent to the weed free check at 4 of 5 locations. Herbicides providing residual activity provided variable control across all locations. Of the herbicides with residual activity evaluated, glyphosate plus linuron provided the best control of glyphosate resistant giant ragweed;however, control was inconsistent across locations and years. Glyphosate plus linuron provided 23% to 99% controland was equal to the weed free check at one location 8 WAA.展开更多
Giant ragweed is a very competitive weed in row crop production and has been found to drastically reduce soybean yield. In 2008, giant ragweed was the first weed species with confirmed resistance to glyphosate in Cana...Giant ragweed is a very competitive weed in row crop production and has been found to drastically reduce soybean yield. In 2008, giant ragweed was the first weed species with confirmed resistance to glyphosate in Canada. As of 2010 there were 48 locations with confirmed glyphosate resistant giant ragweed in Essex, Kent and Lambton counties. In addition, there was suspected resistance to cloransulam-methyl. The objectives of this research were 1) to conduct an expanded field survey on the distribution of glyphosate resistant giant ragweed in Ontario, 2) to determine the distribution of cloransulam-methyl resistant giant ragweed in Ontario, and 3) to determine the distribution of multiple resistant (glyphosate and cloransulam-methyl) giant ragweed in Ontario. In 2011 and 2012 giant ragweed seed was collected from 85 field sites in Essex (16), Kent (34), Lambton (23), Elgin (3), Middlesex (6), Lennox & Addington (1), Huron (1) and Brant (1) counties. In total there are 34 additional locations confirmed with glyphosate resistant giant ragweed in Ontario. There are 11 locations confirmed with cloransulam-methyl resistant giant ragweed and 5 locations with multiple resistance to both glyphosate and cloransulam-methyl. Glyphosate resistant giant ragweed has been found in 4 additional counties.展开更多
Underseeding red clover in winter wheat is a beneficial agronomic practice. Still, many growers tend to forgo this approach. One reason is that herbicides used on winter wheat may injure underseeded red clover, reduci...Underseeding red clover in winter wheat is a beneficial agronomic practice. Still, many growers tend to forgo this approach. One reason is that herbicides used on winter wheat may injure underseeded red clover, reducing its biomass and the subsequent benefits it provides. Therefore, the effect of winter wheat herbicides on underseeded red clover needs to be evaluated. The objectives of this research were to assess the crop tolerance of underseeded red clover to ten winter wheat herbicides used in Ontario, Canada and determine if red clover tolerance differed when the herbicides were applied at various winter wheat growth stages. Experiments were conducted in 2009 and 2010 at four different Ontario locations. Each herbicide treatment was either applied at an early, normal or late timing. Overall, red clover was not affected by herbicides applied at the early timing. The likelihood of herbicides causing injury and reducing biomass of underseeded red clover increased when they were applied at the more advanced winter wheat growth stages. If timing is a constraint, the three herbicides bromoxynil/MCPA, tralkoxydim, and fenoxaprop-pethyl are the safest to use on red clover underseeded to winter wheat. The remaining herbicides 2,4-D, dicamba/MCPA/mecoprop, dichlorprop/2,4-D, thifensulfuron/ tribenuron + MCPA, fluroxypyr + MCPA, pyrasulfotole/bromoxynil, and prosulfuron + bromoxynil are more injurious, with the last two being the most harmful. By having identified the least damaging herbicides on underseeded red clover in winter wheat and the optimal timing for herbicide application, growers are more likely to adopt this beneficial agronomic practice, save on fertilizer costs and improve soil quality.展开更多
Tolpyralate is a new benzoylpyrazole herbicide for weed management in corn. It is recommended to be co-applied with atrazine along with the adjuvants methylated seed oil concentrate (MSO) plus an ammonium nitrogen fer...Tolpyralate is a new benzoylpyrazole herbicide for weed management in corn. It is recommended to be co-applied with atrazine along with the adjuvants methylated seed oil concentrate (MSO) plus an ammonium nitrogen fertilizer, such as urea ammonium nitrate (UAN). Two studies were conducted on glyphosate-resistant (GR) Canada fleabane and GR waterhemp to determine if an additional adjuvant is still required when tolpyralate plus atrazine are tankmixed with a commercial glyphosate formulation (Roundup WeatherMAX®) in corn. Trials were conducted over a two-year period (2018-19) on farms in south western Ontario with confirmed GR populations. When co-applied with Roundup WeatherMAX®, the addition of MSO to tolpyralate + atrazine increased control of GR waterhemp 9%;however, there was no increase in GR Canada fleabane control from the addition of additional adjuvants. At 8 WAA, all treatments provided > 91% and > 84% control of GR waterhemp and GR Canada fleabane, respectively. This study concludes that the addition of Roundup WeatherMAX®to tolpyralate plus atrazine improves the control of GR waterhemp and GR Canada fleabane in corn.展开更多
Six field studies were completed in Ontario (during 2016 to 2018) to assess the tolerance of adzuki, kidney, small red and navy bean to 2,4-D ester at 528 or 1056 g·ai·ha-1 applied 14, 7 and 1 da...Six field studies were completed in Ontario (during 2016 to 2018) to assess the tolerance of adzuki, kidney, small red and navy bean to 2,4-D ester at 528 or 1056 g·ai·ha-1 applied 14, 7 and 1 day before seeding (PP) and 3 days after seeding (PRE). 2,4-D applied PP or PRE caused as much as 4%, 6%, 7% and 8% injury in adzuki, kidney, small red and navy (white) bean, respectively. There was an increase in bean injury as the preplant interval decreased. At 1 WAE, 2,4-D applied at 1056 g·ai·ha-1 14, 7 and 1 day PP and 3 days after seeding caused up to 6%, 10%, 18% and 5% visible bean injury, respectively. The level of injury decreased over time with minimal bean injury (0 to 3%) at 8 WAE. Bean stand counts were similar to the non-treated control with 2,4-D applied at various timings except at 1 day PP when 2,4-D at the 2X rate decreased bean stand 13%. There was up to 23% and 43% decrease in bean dry weight with 2,4-D applied PP at 528 and 1056 g·ai·ha-1 7 and 1 day PP, respectively. Bean height (6 WAE) was not affected by 2,4-D applied at various timings except at 1 day PP when 2,4-D (1056 g·ai·ha-1) decreased bean height 10%. Additionally, there was no effect of 2,4-D treatments on bean maturity or yield. Based on these results, the safest times to apply 2,4-D are 14 days before seeding or PRE. Injury was higher when 2,4-D was applied 7 and 1 day PP. Injury was lower in adzuki bean compared to kidney, small red or navy bean.展开更多
文摘A total of twelve field trials (6 with kidney bean and 6 with white bean) were conducted over a three-year period (2010 to 2012) at various locations in Ontario to evaluate the tolerance of kidney and white bean to imazethapyr applied preplant incorporated (PPI), preemergence (PRE), and postemergence (POST) at 37.5, 75 and 150 g·ai·ha-1. Imazethapyr applied PPI or PRE in kidney or white bean caused 0%-1%, 0%-4%, and 0%-9% injury at 1, 2, and 4 weeks after application (WAA), respectively. However, the injury was transient and had no adverse effect on shoot dry weight, height, seed moisture content, and yield of kidney or white bean except for shoot dry weight which was reduced 32% with imazethapyr applied PPI compared to the weed free control in white bean. Imazethapyr applied POST in kidney or white bean caused as much as 17%, 18%, and 11% injury at 1, 2, and 4 WAA, respectively. There was no adverse effect on shoot dry weight, height, seed moisture content, and yield of kidney or white bean except for imazethapyr applied POST which increased seed moisture content 1.9% compared to the weed free control in white bean. Based on these results, there is an adequate margin of crop safety in dry bean to imazethapyr applied PPI or PRE at 37.5 or 75 g·ai·ha-1 in kidney and white beans. However, there is not an adequate margin of crop safety for imazethapyr applied POST at rates higher than 37.5 g·ai·ha-1 in kidney and white bean.
文摘There is limited information available on the effect of biostimulants such as Crop Booster or RR SoyBooster on corn, oats and winter wheat under Ontario environmental conditions. A total of 37 field experiments were conducted in corn, oats and winter wheat at two locations (Ridgetown and Exeter, Ontario, Canada) to evaluate the effect of Crop Booster or RR SoyBooster on crop injury, weed control and yield. The addition of Crop Booster to glyphosate did not affect weed control or corn yield except at 4 weeks after herbicide application (WAA) when control of pigweed species was increased by 1% and at 4 and 8 WAA when control of common lambsquarters was reduced by 1%. The addition of RR SoyBooster to glyphosate did not affect crop injury, weed control or corn yield. The addition of Crop Booster to glyphosate + topramezone + atrazine did not affect crop injury, weed control or corn yield except at 4 WAA when control of common ragweed was reduced by 1%. The tank mix of Crop Booster with glyphosate + thiencarbazone-methyl did not affect crop injury, weed control or corn yield except at 4 WAA when control of green foxtail and annual grasses were reduced by 2% and 1%, respectively. The addition of Crop Booster to bromoxynil/ MCPA had no significant effect on crop injury, weed control or yield of oats or winter wheat.
文摘New herbicide options are needed for postemergence (POST) broadleaf weed control in adzuki bean. A field study, of five experiments, was conducted over a three-year period (2014, 2015, 2016) in Ontario to evaluate the tolerance of adzuki bean to the POST application of acifluorfen (600 and 1200 g·ai·ha-1), fomesafen (240 and 480 g·ai·ha-1), bentazon (1080 and 2160 g·ai·ha-1), imazethapyr (100 and 200 g·ai·ha-1) and halosulfuron-methyl (75 and 150 g·ai·ha-1). Acifluorfen and fomesafen applied POST caused as much as 12% visible injury at the 1X rate and 20% visible injury at the 2X rate but had no adverse effect on adzuki bean population, shoot dry weight, height, maturity or yield. Bentazon caused as much as 23% visible injury at 1080 g·ai·ha-1 and 28% visible injury at 2160 g·ai·ha-1 but caused no adverse effect on adzuki bean population, shoot dry weight, height, maturity or yield at either rate, except at 2160 g·ai·ha-1 which reduced shoot dry weight 20% and height 12%. Imazethapyr caused as much as 22% visible injury at 100 g·ai·ha-1 and 34% visible injury at 200 g·ai·ha-1 but caused no adverse effect on adzuki bean population, shoot dry weight, height, maturity or yield at either rate except at 200 g·ai·ha-1 which delayed maturity slightly. Halosulfuron-methyl caused as much as 65% visible injury and reduced shoot dry weight, height and yield 64%, 41%, and 28%, respectively. This research concludes that acfluorfen, fomesafen, bentazon, imazethapyr and halosulfuron at the rates evaluated can cause the significant injury in adzuki bean.
文摘Glyphosate resistant (GR) Canada fleabane has spread quickly across southwestern Ontario and new strategies for the control of this competitive weed must be developed especially in no-tillage crops. A premix of 2,4-D choline and glyphosate dimethylamine (DMA) has been developed for application on tolerant corn, soybean and cotton crops that provides an option for the control of this problematic GR weed. The objective of this research was to determine the required dose needed to effectively control GR Canada fleabane at different size categories in field and greenhouse experiments. In the field experiments, nine rates of 2,4-D choline/glyphosate DMA (53.8 to 13,760 g·ae·ha-1) were applied to GR Canada fleabane that were 10 cm in diameter/tall, 20 cm tall or 30 cm tall. Similarly, in the greenhouse, seven rates of 2,4-D choline/glyphosate DMA (0 to 3440 g·ae·ha-1) were applied to 10, 20 and 30 cm tall GR Canada fleabane plants. The three different size classes of GR Canada fleabane responded similarly to 2,4-D choline/glyphosate DMA in the field experiment. In the greenhouse there were some differences in control for the three size classes of GR Canada fleabane with 2,4-D choline/glyphosate DMA;the 20 and 30 cm tall plants required similar rates to provide equivalent control, but the 10 cm plants required a lower rate. In all situations, greater than 1720 g·ae·ha-1 of 2,4-D choline/glyphosate DMA was required to provide 95% control of 10, 20 and 30 cm tall Canada fleabane in greenhouse (35 DAA) and field experiments (8 WAA), respectively.
文摘Tolerance of carrot and red beet to s-metolachlor at three application timings—pre-emergence to crop (PRE), early postemergence (crop at two to four leaf stage-EPOST), and late postemergence (crop at five to seven leaf stage-LPOST) —was determined from 2008 to 2010. LPOST applications of s-metolachlor reduced carrot above ground plant dry weight, marketable yield and grower payment, but did not affect carrot length. PRE and LPOST applications of s-metolachlor reduced red beet above ground plant dry weight, total marketable yield, yield of No. 2 and No. 3 red beet, and grower payment. Our findings indicate that while carrot may be tolerant to PRE applications of s-metolachlor, applications made after the 5 leaf stage reduced plant dry weight enough to impact marketable yield and grower payment. In red beet, the potential reduction in growth, yield and grade would not justify the utility of a PRE or LPOST applica- tion timing.
文摘A population of common ragweed in Ontario was confirmed to be resistant to glyphosate in 2011. Group 2 [acetolactate synthase (ALS) inhibitors] resistant common ragweed was first confirmed in Ontario in 2000. Previously, glyphosate provided excellent control of common ragweed in glyphosate resistant soybean but with the confirmation of glyphosate resistant (GR) common ragweed, alternative herbicides need to be evaluated. Eight field trials with preplant herbicides were completed over two years (2013 and 2014) in fields with confirmed GR common ragweed. Tank-mixes of glyphosate and linuron or metribuzin provided 88% - 99% and 86% - 98% control 4 weeks after application (WAA) and 80% - 92% and 80% - 95% control 8 WAA, respectively. However, these herbicides also had among the highest environmental impact of the herbicides tested. Based on the results of these studies, GR common ragweed can be controlled with residual herbicides when applied preemergence in soybean. Currently, there are no post emergence herbicides that provide adequate control of GR common ragweed, therefore, preemergence herbicides with residual are essential for full season control.
文摘There are a limited number of postemergence (POST) herbicides available for weed management in mung bean production in Ontario. Five field studies were conducted in 2010, 2011 and 2012 near Exeter, Ontario and in 2011 and 2012 near Ridgetown, Ontario to determine the tolerance of mung bean to fomesafen, bentazon, bentazon + fomesafen and halosulfuron applied POST at the 1X and 2X proposed manufacturer’s recommended rate. Bentazon caused 5%-29%, 4%-31%, and 2%-18% injury, fomesafen caused 3%-17%, 1%-7%, and 0%-6% injury, bentazon + fomesafen caused 6%-40%, 4%-37%, and 1%-20% injury, and halosulfuron caused 13%-65%, 8%-75%, and 5%-47% injury in mung bean at 1, 2, and 4 weeks after treatment (WAT), respectively. At Exeter, fomesafen had no adverse effect on height of mung bean but bentazon, bentazon + fomesafen and halosulfuron decreased mung bean height as much as 5% compared to the untreated control. At Ridgetown, there was no decrease in mung bean height due to the herbicides applied. Fomesafen had no adverse effect on shoot dry weight of mung bean but bentazon, bentazon + fomesafen and halosulfuron decreased shoot dry weight of mung beans as much as 43%, 47%, and 57%, respectively. Fomesafen, bentazon, bentazon + fomesafen and halosulfuron had no adverse effect on the seed moisture content and seed yield of mung bean with the exception of halosulfuron applied POST at 70 g ai ha-1 which increased seed moisture content 0.4% at Exeter and 1.4% at Ridgetown and decreased yield 16% at Exeter compared to the untreated control. Based on these results, there is not an adequate margin of crop safety for bentazon, bentazon + fomesafen and?halosulfuron applied POST in mung bean. However, there is potential for fomesafen applied POST at the proposed manufacturer’s rate of 240 g ai ha-1 in mung bean production.
文摘Only one herbicide mode of action (ALS inhibitor) is currently available to Ontario dry bean producers for soil-applied broadleaf weed control. Four field studies were conducted over two years (2014, 2015) to examine the tolerance of four market classes of dry beans to sulfentrazone (210 and 420 g·ai·ha<sup>-1</sup>) and pyroxasulfone (100 and 200 g·ai·ha<sup>-1</sup>) applied alone and in combination. The registration of these two herbicides would provide Ontario dry bean producers with two additional modes of action for broadleaf weed control. Pyroxasulfone caused up to 23%, 6%, 7% and 10% injury in adzuki, kidney, small red Mexican and white bean, respectively;sulfentrazone caused up to 51%, 12%, 15% and 44% injury and the combination caused up to 90%, 23%, 29% and 62% injury, respectively. Kidney and small red Mexican bean density, height, seed moisture content and yield were not affected. Pyroxasulfone (200 g·ai·ha<sup>-1</sup>) + sulfentrazone (420 g·ai·ha<sup>-1</sup>) reduced adzuki and white bean density, shoot dry weight, height and yield. This study concludes that pyroxasulfone (100 g·ai·ha<sup>-1</sup>) + sulfentrazone (210 g·ai·ha<sup>-1</sup>) applied PRE can be safely used to control weeds in Ontario kidney and small red Mexican bean production.
文摘The objective of this research was to evaluate the efficacy of various pre-emergence (PRE) and post-emergence (POST) herbicides for the control of volunteer adzuki bean (Vigna angularis (Willd.) Ohwi & Ohashi) in soybean (Glycine max L.). Trials were conducted at two locations in 2005, 2006, 2007, and 2009. Experiments were arranged in a randomized complete block design with either five PRE or nine POST herbicides. Volunteer adzuki bean interference in soybean resulted in yield loss of up to 25%. Cloransulam-methyl, linuron, metribuzin, flumetsulam, and imazethapyr applied PRE provided up to 6, 24, 14, 8, and 0% control, respectively at 8 weeks after emergence (WAE), while acifluorfen, fomesafen, bentazon, thifensulfuron-methyl, cloransulam-methyl, imazethapyr, and imazethapyr plus bentazon applied POST provided 2, 2, 5, 34, 6, 4, and 12% control, respectively at 8 weeks after application (WAA). Generally, with the aforementioned herbicides, soybean yield was equivalent to the weedy control and soybean grain contamination with adzuki bean seed was consistently above the 1% maximum threshold. Chlorimuron-ethyl and glyphosate applied POST provided up to 84 and 94% visual control at 8 WAA, respectively, decreased adzuki bean density, biomass, and seed production, and generally decreased soybean contamination with adzuki bean below the 1% threshold. The only herbicides evaluated in this study that controlled volunteer adzuki bean in soybean were chlorimuron-ethyl (9 g ai.ha-1) and glyphosate (900 g ai.ha-1) applied POST. All the other PRE and POST herbicides evaluated did not provide adequate control of volunteer adzuki bean in soybean.
文摘There are a limited number of herbicides registered for weed management in white bean production in Ontario, Canada. Five field experiments were completed in Ontario from 2016 to 2018 to compare the efficacy of trifluralin and ethalfluralin applied alone and in combination with halosulfuron, applied preplant incorporated (PPI), for weed control efficacy and white bean tolerance and seed yield. At 2 and 4 WAE, there was no white bean injury from the herbicide treatments evaluated. Trifluralin applied PPI provided up to 32%, 99%, 13%, 99%, 27%, 99% and 99% control of velvetleaf, redroot pigweed, common ragweed, common lambsquarters, wild mustard, barnyardgrass and green foxtail, respectively. Trifluralin and ethalfluralin provide similar control of velvetleaf, redroot pigweed, barnyardgrass and green foxtail control, however, ethalfluralin is slightly more efficacious on common ragweed, common lambsquarters and wild mustard. Halosulfuron (35 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>), applied PPI, provided as much as 76%, 98%, 96%, 96%, 100%, 19% and 23% control of velvetleaf, redroot pigweed, common ragweed, common lambsquarters, wild mustard, barnyardgrass and green foxtail, respectively. Trifluralin (600 or 1155 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>) + halosulfuron (35 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>), applied PPI, provided up to 88%, 100%, 98%, 100%, 100%, 99% and 98% control of velvetleaf, redroot pigweed, common ragweed, common lambsquarters, wild mustard, barnyardgrass and green foxtail, respectively. Ethalfluralin (810 or 1080 ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>) + halosulfuron (35 g<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ai<span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">∙</span></span></span>ha<sup><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span>1</sup>) provided similar control. Weed interference decreased white bean seed yield 44% - 45% with trifluralin, 30% - 41% with ethalfluralin and 34% with halosulfuron. However, decreased weed interference with trifluralin and ethalfluralin applied in combination with halosulfuron resulted white bean seed yield that was similar to the weed-free control. Trifluralin or ethalfluralin co-applied with halosulfuron can be safely used in white bean production for the control of common annual grass and broadleaf weeds in Ontario.
文摘Five field trials were conducted over a two-year period (2013, 2014) to determine the control of glyphosate-resistant (GR) giant ragweed with isoxaflutole (IFT) and metribuzin (MTZ) applied alone and in combination. Treatments were designed to assess the dose response of an IFT plus MTZ tank-mix as well as each chemical applied alone to classify the response using Flint’s adaptation of Colby’s equation. Two factor factorial experiments were performed in the growth room to ascertain the response of IFT versus glyphosate, IFT versus MTZ, and IFT plus MTZ versus glyphosate on single plants. Field experiments evaluated the control of GR giant ragweed with IFT plus MTZ in tank-mix in a 1:4 ratio. The rate of IFT plus MTZ for 80% control of GR giant ragweed at 4 and 8 weeks after application (WAA) was 518 (104 g a.i. ha<sup>-1</sup> IFT + 414 g a.i. ha<sup>-1</sup> MTZ) and 631 g a.i. ha<sup>-1</sup> (126 g a.i. ha<sup>-1</sup> IFT + 505 g a.i. ha<sup>-1</sup> MTZ), respectively. A rate of 668 and 467 g a.i. ha<sup>-1</sup> was required to reduce GR giant ragweed density and biomass by 80%, respectively. Field experiments evaluating the control of GR giant ragweed with tank-mixes of IFT plus MTZ, where glyphosate was a constant tank-mix partner, were mostly synergistic. However, the low tank-mix rate (52.5 + 210 g a.i. ha<sup>-1</sup>) had an additive response for GR giant ragweed biomass reduction. When tested in the greenhouse and growth room, glyphosate susceptible (GS) giant ragweed showed some antagonism with glyphosate and isoxaflutole tank-mixes at rates less than commercial field rates. GR giant ragweed showed an additive response across all treatments in the growth room. Greenhouse experiments evaluating IFT versus MTZ and IFT plus MTZ versus glyphosate revealed all tank-mix treatments to be synergistic at 2 WAA.
文摘The use of glyphosate-resistant corn has facilitated a shift from a reliance on preemergence residual herbicides to postemergence (POST) herbicides, and in some cases exclusively glyphosate. Glyphosate is a non-selective herbicide that is relatively slow-acting, which may allow weeds to continue to compete with corn after application and potentially decrease crop yield. The addition of several POST corn herbicides, with some residual control, to an early-season glyphosate application was examined to determine if the tankmix combination would improve the speed of weed control compared to glyphosate applied alone. Seven field trials were conducted over three years (2009, 2010 and 2011) near Ridgetown and Exeter, Ontario. The control of common ragweed was improved 3 days after application (DAA) with three POST glyphosate tankmixes compared to glyphosate alone. However control was still less than 55%. Depending on the weed species examined, at 28 DAA two of the glyphosate tankmix treatments tested provided better common ragweed, common lambsquarters, or green foxtail control than glyphosate alone. Treatments providing better weed control at 28 DAA also typically decreased weed density compared to glyphosate alone.
文摘Glyphosate-resistant (GR) giant ragweed has recently been identified in southwestern Ontario and has the potential to be a significant problem for regional corn producers. Eight field trials [four with preplant (PP) and four with postemergence (POST) herbicides] were conducted from 2013 to 2014 on various Ontario farms infested with GR giant ragweed to determine the efficacy of PP and POST tank-mixes in corn. Glyphosate tank-mixed with atrazine, dicamba, dicamba/atrazine, mesotrione plus atrazine, flumetsulam, isoxaflutole plus atrazine, saflufenacil/dimethenamid-P, S-metolachlor/atrazine and rimsulfuron applied PP provided up to 54%, 95%, 93%, 95%, 40%, 89%, 91%, 50% and 93% control of GR giant ragweed and reduced dry weight 69%, 100%, 99%, 100%, 30%, 92%, 98%, 66% and 99%, respectively. POST application of glyphosate alone and tank-mixed with 2,4-D ester, atrazine, dicamba, dicamba/diflufenzopyr, dicamba/atrazine, bromoxynil plus atrazine, prosulfuron plus dicamba, mesotrione plus atrazine, topramezone plus atrazine, tembotrione/thiencarbazone-methyl and glufosinate provided up to 31%, 84%, 39%, 94%, 89%, 86%, 83%, 78%, 72%, 43%, 63% and 58% GR giant ragweed and reduced dry weight 55%, 99%, 72%, 99%, 99%, 98%, 96%, 96%, 93%, 89%, 91% and 95%, respectively. In general, PP control of GR giant ragweed was greater than POST applied herbicides evaluated. Based on these results, glyphosate tank-mixes containing dicamba or mesotrione plus atrazine applied PP, and dicamba applied POST will provide the most consistent control of GR giant ragweed in corn.
文摘Twenty-two field experiments (six maize (Zea mays L.) and five soybean [Glycine max (L.) Merr.] using low glyphosate doses to assess weed control and six maize and five soybean using high glyphosate doses to assess tolerance) were conducted from 2010 to 2012 at two locations in southern Ontario, Canada to compare the commercially available glyphosate formulations of Roundup Weather MAX?, Clearout?41 Plus, and Wise Up? (WeatherMAX, Clearout, and WiseUp, respectively). Inmaize and soybean, control of velvetleaf, pigweed species, common lambs quarters, and green foxtail 4 weeks after treatment (WAT) using 900 g·ae·ha-1 ranged from at least 85% to 99%, regardless of formulation. By 8 WAT with 900 g·ae·ha-1, control of these weeds generally declined, but still ranged from 82% to 97% across all formulations. At harvest, maize yields were similar to the weed-free control for 900 g·ae·ha-1 of glyphosate as WeatherMAX and Clearout;however, reduced weed control with WiseUp resulted in an 8.8% yield loss. For soybean, yields were similar to the weed-free control, regardless of formulation or dose. In the tolerance experiments, 2.1% and 2.8% injury was observed 4 WAT for maize treated with 3600 g·ae·ha-1 of glyphosate as WeatherMAX and WiseUp, respectively. However, maize yields were unaffected by glyphosate formulation or dose. In soybean, visible injury of 8.5%, 4.5%, and 3.7% was observed 1 WAT with 5400 g·ae·ha-1 of glyphosate as WeatherMAX, WiseUp, and Clearout, respectively;by 8 WAT, visible injury was similar to the untreated control, regardless of formulation or dose. The early injury from 5400 g·ae·ha-1 of glyphosate resulted in 8.5%, 4.6%, and 5.5% yield loss for the WeatherMAX, WiseUp, and Clearout formulations, respectively.
文摘Fifteen field experiments were conducted from 2009 to 2012 in Ontario, Canada and Michigan, USA to determine the tolerance of corn (Zea mays L.) to early (spike or 1- to 2-leaf stage) or late (8- or 10-leaf stage) applications of 900, 1800, 3600, or 7200 g·ae·ha-1 of glyphosate. Postemergence applications were evaluated for corn injury, cob length and deformity, crop moisture at harvest, and yield in the absence of weed competition. In the early application experiment, no visible injury was detected with applications of up to 3600 g·ae·ha-1;however, 1.4% injury was observed 4 weeks after treatment (WAT) when 7200 g·ae·ha-1 was applied to 1- to 2-leaf stage corn. Yet by harvest, the observed injury was transient as yields were similar to the untreated control regardless of glyphosate dose or timing. In the late application experiment, visible injury tended to increase with glyphosate dose. In addition, for corn treated with 7200 g·ae·ha-1 at the 10-leaf stage, injury increased over time as 6%, 11%, and 12% injury was observed 1, 2, and 4 WAT, respectively. Similar to the visible injury of vegetative tissue, cob deformity and reductions in yield tended to increase with glyphosate dose, but this response varied and the data were pooled into two environment groups. For example, in one environment group, corn treated with 7200 g·ae·ha-1 at the 8- and 10-leaf stage had a 9.5% and 14.6% reduction in yield, respectively. Whereas in another environment group, corn yields were similar to the untreated control regardless of glyphosate dose or timing. This research demonstrated that commercially available corn hybrids have tolerance to glyphosate at doses greater than what has been previously published or could reasonably be expected during spray overlaps in a field.
基金Funding for this project was provided in part by Monsanto Canada Inc.the Grain Farmers of Ontario and the Agricultural Adaptation Council through the Canadian Agricultural Adaptation Program.
文摘Giant ragweed was the first glyphosate resistant weed identified in Canada. It is a very competetive weed in row crop production and has been found to drastically reduce yields of soybean;therefore, control of this competitive weed is essential. The objective of this study was to determine effective control options for glyphosate resistant giant ragweed in soybean with herbicides applied preplant. Eighteen herbicide combinations were evaluated in field studies conducted in 2011 and 2012 at five locations with confirmed glyphosate resistant giant ragweed. Glyphosate plus 2,4-D ester or amitrole provided the best control of glyphosate resistant giant ragweed 4 WAA. Glyphosate plus 2,4-D ester provided 98 to 99% control and was equivalent to the weed free check at all locations. Glyphosate plus amitrole provided 90% to 93% control and was equivalent to the weed free check at 4 of 5 locations. Herbicides providing residual activity provided variable control across all locations. Of the herbicides with residual activity evaluated, glyphosate plus linuron provided the best control of glyphosate resistant giant ragweed;however, control was inconsistent across locations and years. Glyphosate plus linuron provided 23% to 99% controland was equal to the weed free check at one location 8 WAA.
基金Funding for this project was provided in part by Monsanto Canada Inc.the Grain Farmers of Ontario and the Agricultural Adaptation Council through the Canadian Agricultural Adaptation Program.
文摘Giant ragweed is a very competitive weed in row crop production and has been found to drastically reduce soybean yield. In 2008, giant ragweed was the first weed species with confirmed resistance to glyphosate in Canada. As of 2010 there were 48 locations with confirmed glyphosate resistant giant ragweed in Essex, Kent and Lambton counties. In addition, there was suspected resistance to cloransulam-methyl. The objectives of this research were 1) to conduct an expanded field survey on the distribution of glyphosate resistant giant ragweed in Ontario, 2) to determine the distribution of cloransulam-methyl resistant giant ragweed in Ontario, and 3) to determine the distribution of multiple resistant (glyphosate and cloransulam-methyl) giant ragweed in Ontario. In 2011 and 2012 giant ragweed seed was collected from 85 field sites in Essex (16), Kent (34), Lambton (23), Elgin (3), Middlesex (6), Lennox & Addington (1), Huron (1) and Brant (1) counties. In total there are 34 additional locations confirmed with glyphosate resistant giant ragweed in Ontario. There are 11 locations confirmed with cloransulam-methyl resistant giant ragweed and 5 locations with multiple resistance to both glyphosate and cloransulam-methyl. Glyphosate resistant giant ragweed has been found in 4 additional counties.
基金funded in part by the Grain Farmers of Ontario,the Agricultural Adaptation Council(CanAdvance Program)and the Ontario Ministry of Agriculture,Food and Rural Affairs.
文摘Underseeding red clover in winter wheat is a beneficial agronomic practice. Still, many growers tend to forgo this approach. One reason is that herbicides used on winter wheat may injure underseeded red clover, reducing its biomass and the subsequent benefits it provides. Therefore, the effect of winter wheat herbicides on underseeded red clover needs to be evaluated. The objectives of this research were to assess the crop tolerance of underseeded red clover to ten winter wheat herbicides used in Ontario, Canada and determine if red clover tolerance differed when the herbicides were applied at various winter wheat growth stages. Experiments were conducted in 2009 and 2010 at four different Ontario locations. Each herbicide treatment was either applied at an early, normal or late timing. Overall, red clover was not affected by herbicides applied at the early timing. The likelihood of herbicides causing injury and reducing biomass of underseeded red clover increased when they were applied at the more advanced winter wheat growth stages. If timing is a constraint, the three herbicides bromoxynil/MCPA, tralkoxydim, and fenoxaprop-pethyl are the safest to use on red clover underseeded to winter wheat. The remaining herbicides 2,4-D, dicamba/MCPA/mecoprop, dichlorprop/2,4-D, thifensulfuron/ tribenuron + MCPA, fluroxypyr + MCPA, pyrasulfotole/bromoxynil, and prosulfuron + bromoxynil are more injurious, with the last two being the most harmful. By having identified the least damaging herbicides on underseeded red clover in winter wheat and the optimal timing for herbicide application, growers are more likely to adopt this beneficial agronomic practice, save on fertilizer costs and improve soil quality.
文摘Tolpyralate is a new benzoylpyrazole herbicide for weed management in corn. It is recommended to be co-applied with atrazine along with the adjuvants methylated seed oil concentrate (MSO) plus an ammonium nitrogen fertilizer, such as urea ammonium nitrate (UAN). Two studies were conducted on glyphosate-resistant (GR) Canada fleabane and GR waterhemp to determine if an additional adjuvant is still required when tolpyralate plus atrazine are tankmixed with a commercial glyphosate formulation (Roundup WeatherMAX®) in corn. Trials were conducted over a two-year period (2018-19) on farms in south western Ontario with confirmed GR populations. When co-applied with Roundup WeatherMAX®, the addition of MSO to tolpyralate + atrazine increased control of GR waterhemp 9%;however, there was no increase in GR Canada fleabane control from the addition of additional adjuvants. At 8 WAA, all treatments provided > 91% and > 84% control of GR waterhemp and GR Canada fleabane, respectively. This study concludes that the addition of Roundup WeatherMAX®to tolpyralate plus atrazine improves the control of GR waterhemp and GR Canada fleabane in corn.
文摘Six field studies were completed in Ontario (during 2016 to 2018) to assess the tolerance of adzuki, kidney, small red and navy bean to 2,4-D ester at 528 or 1056 g·ai·ha-1 applied 14, 7 and 1 day before seeding (PP) and 3 days after seeding (PRE). 2,4-D applied PP or PRE caused as much as 4%, 6%, 7% and 8% injury in adzuki, kidney, small red and navy (white) bean, respectively. There was an increase in bean injury as the preplant interval decreased. At 1 WAE, 2,4-D applied at 1056 g·ai·ha-1 14, 7 and 1 day PP and 3 days after seeding caused up to 6%, 10%, 18% and 5% visible bean injury, respectively. The level of injury decreased over time with minimal bean injury (0 to 3%) at 8 WAE. Bean stand counts were similar to the non-treated control with 2,4-D applied at various timings except at 1 day PP when 2,4-D at the 2X rate decreased bean stand 13%. There was up to 23% and 43% decrease in bean dry weight with 2,4-D applied PP at 528 and 1056 g·ai·ha-1 7 and 1 day PP, respectively. Bean height (6 WAE) was not affected by 2,4-D applied at various timings except at 1 day PP when 2,4-D (1056 g·ai·ha-1) decreased bean height 10%. Additionally, there was no effect of 2,4-D treatments on bean maturity or yield. Based on these results, the safest times to apply 2,4-D are 14 days before seeding or PRE. Injury was higher when 2,4-D was applied 7 and 1 day PP. Injury was lower in adzuki bean compared to kidney, small red or navy bean.
