Herbicide-Resistant Canola (Brassica napus) Response and Weed Control with Postemergence Herbicides

2006 ◽  
Vol 20 (3) ◽  
pp. 551-557 ◽  
Author(s):  
Timothy L. Grey ◽  
Paul L. Raymer ◽  
David C. Bridges

Field studies were conducted to evaluate weed control in herbicide-resistant canola in Georgia. The resistant canola cultivars and respective herbicides were ‘Pioneer 45A76’ and imazamox, ‘Hyola 357RR’ and glyphosate, and ‘2573 Invigor’ and glufosinate. Weed seed of Italian ryegrass and wild radish were sown simultaneously in October with canola and control of these species was evaluated along with other naturally occurring weeds. Herbicide treatments for the respective herbicide-resistant canola cultivar were imazamox at 0.035 and 0.071 kg ai/ha, glyphosate at 0.84 and 1.64 kg ae/ha, and glufosinate at 0.5 and 1.0 kg ai/ha. Herbicides were applied at one– two-leaf (LF) and three–four-LF canola stages. There was no significant injury to any canola cultivar as a result of herbicide rate or timing of application. By midseason (February), imazamox effectively controlled wild radish, henbit, and shepherd's-purse at both rates and at both timings. When applied to three–four-LF canola, the higher rates of glyphosate and glufosinate were required to provide 75% or greater control of Italian ryegrass, wild garlic, and henbit. Glufosinate did not adequately control wild radish at either rate or application timing. Greenhouse experiments provided similar results.

Weed Science ◽  
2011 ◽  
Vol 59 (3) ◽  
pp. 390-397 ◽  
Author(s):  
Ivan Sartorato ◽  
Antonio Berti ◽  
Giuseppe Zanin ◽  
Claudio M. Dunan

The introduction of herbicide-resistant crops and postemergence herbicides with a wide action spectrum shifted the research focus from how to when crops should be treated. To maximize net return of herbicide applications, the evolution of weed–crop competition over time must be considered and its effects quantified. A model for predicting the yield trend in relation to weed removal time, considering emergence dynamics and density, was tested on data from glyphosate-resistant soybean grown in cropping systems in Italy and Argentina. Despite an ample variation of weed emergence dynamics and weed load in the four trials, the model satisfactorily predicted yield loss evolution. The estimated optimum time for weed control (OTWC) varied from about 18 d after soybean emergence in Argentina to 20 to 23 d in Italy, with time windows for spraying ranging from 14 to 28 d. Within these limits a single glyphosate application ensures good weed control at low cost and avoids side effects like the more probable unfavorable weed flora evolution with double applications and the presence of residues in grains. Despite the apparent simplicity of weed control based on nonselective herbicides, the study outlines that many variables have to be considered to optimize weed management, particularly for the time evolution of the infestation and, subsequently, a proper timing of herbicide application.


HortScience ◽  
2008 ◽  
Vol 43 (6) ◽  
pp. 1823-1825 ◽  
Author(s):  
Katie J. Kammler ◽  
S. Alan Walters ◽  
Bryan G. Young

Field studies were conducted to evaluate postemergence combinations of halosulfuron plus sethoxydim or clethodim with various adjuvants for effects on jack-o-lantern pumpkin (Cucurbita pepo L.) injury and yields and control of large [Digitaria sanguinalis (L.) Scop.] and smooth crabgrass [D. ischaemum (Schreb. ex Schweig.) Schreb. ex Muhl.]. Halosulfuron caused 27% and 14% pumpkin injury at 28 d after postemergence treatment (DAPT) in 2004 and 2005, respectively. Tank-mixing sethoxydim or clethodim with halosulfuron did not increase pumpkin injury compared with halosulfuron alone. Pumpkin injury from sethoxydim and clethodim alone at 28 DAPT ranged from 19% to 23% in 2004, but was only 7% to 8% in 2005. The addition of oil-based adjuvants to halosulfuron did not affect pumpkin injury compared with using a nonionic surfactant (NIS). The tank mixture of halosulfuron and sethoxydim did not affect crabgrass control regardless of adjuvant. However, the addition of halosulfuron to clethodim plus NIS reduced control of crabgrass from 89% to 77% at 28 DAPT. Crabgrass control was unaffected by the addition of halosulfuron to clethodim with crop oil concentrate (COC) or a NIS/COC blend. None of the herbicide treatments provided pumpkin yield (fruit no./ha) similar to the weed-free control. The pumpkin yield of treatments using postemergence herbicides was at least 50% less than the weed-free treatment. These low pumpkin yields were most likely the result of the combination of pumpkin injury from the herbicide applications and insufficient weed control.


2014 ◽  
Vol 28 (2) ◽  
pp. 361-370 ◽  
Author(s):  
Jason A. Bond ◽  
Thomas W. Eubank ◽  
Robin C. Bond ◽  
Bobby R. Golden ◽  
H. Matthew Edwards

Dense populations of glyphosate-resistant (GR) Italian ryegrass are problematic for spring burndown herbicide programs and crop establishment in the midsouthern United States. Two field studies were conducted to evaluate fall-applied residual herbicides for control of GR Italian ryegrass and to identify the most effective application timing for these herbicides. Fall applications of clomazone at 0.84 and 1.12 kg ai ha−1, pyroxasulfone at 0.16 kg ai ha−1, andS-metolachlor at 1.79 kg ai ha−1controlled GR Italian ryegrass ≥ 93% 180 d after application. Control from incorporated applications of pendimethalin at 1.59 kg ai ha−1and trifluralin at 1.68 kg ai ha−1and surface applications ofS-metolachlor at 1.42 kg ha−1provided control similar to the best treatments. Glyphosate-resistant Italian ryegrass control following clomazone, pyroxasulfone,S-metolachlor, or trifluralin applied in mid September, October, or November exceeded that from fall tillage by 19 to 56% at 90 and 140 d after the last treatment. Pyroxasulfone andS-metolachlor controlled more GR Italian ryegrass following October or November applications compared with those in September at both 90 and 140 d after the last application timing. However, the benefit of delaying clomazone application from October to November was not realized until the last evaluation (140 d after the last treatment). Clomazone, pyroxasulfone, andS-metolachlor offer growers the best opportunity for residual control of GR Italian ryegrass, and control is optimized when these herbicides are applied in November.


2014 ◽  
Vol 28 (3) ◽  
pp. 552-559 ◽  
Author(s):  
Timothy L. Grey ◽  
Fred S. Turpin ◽  
Lenny Wells ◽  
Theodore M. Webster

A survey was conducted in 2012 in Georgia to determine the most troublesome weeds in pecan orchards and document common herbicide weed control practices. Weed control practices and infestations in pecan were divided between winter and summer seasons. The most troublesome pecan winter weed species were wild radish and Italian ryegrass, whereas the most troublesome summer season weeds were Palmer amaranth and bermudagrass. Other weeds included crabgrass species, bahiagrass, Florida pusley, purslane species, morningglory species, curly dock, and cutleaf evening-primrose. The most widely used POST herbicide in both the winter and summer season was glyphosate. The most commonly used year-round herbicides with soil persistence were pendimethalin, diuron, flumioxazin, halosulfuron, simazine, indaziflam, and oryzalin. Use of multiple herbicides, PRE- and POST-contact and soil-persistent, with various herbicide mechanisms of action, have benefited pecan producers by providing year-round weed control, despite herbicide-resistant weeds being widely established in this region.


2021 ◽  
pp. 1-22
Author(s):  
Marcelo L. Moretti

Abstract Italian ryegrass has become a problematic weed in hazelnut orchards of Oregon because of the presence of herbicide-resistant populations. Resistant and multiple-resistant Italian ryegrass populations are now the predominant biotypes in Oregon; there is no information on which herbicides effectively control Italian ryegrass in hazelnut orchards. Six field studies were conducted in commercial orchards to evaluate Italian ryegrass control with POST herbicides. Treatments included flazasulfuron, glufosinate, glyphosate, paraquat, rimsulfuron, and sethoxydim applied alone or in selected mixtures during early spring when plants were in the vegetative stage. Treatment efficacy was dependent on the experimental site. The observed range of weed control 28 d after treatment was 13 to 76 % for glyphosate, 1 to 72% for paraquat, 58 to 88% for glufosinate, 16 to 97 % for flazasulfuron, 8 to 94% for rimsulfuron, and 25 to 91% for sethoxydim. Herbicides in mixtures improved control of Italian ryegrass compared to single active ingredients based on contrast analysis. Herbicides in mixture increased control by 27% compared to glyphosate, 18% to rimsulfuron, 15% to flazasulfuron, 19% to sethoxydim, and 12% compared to glufosinate when averaged across all sites, but mixture not always improved ground coverage of biomass reduction. This complex site-specific response highlights the importance of record-keeping for efficient herbicide use. Glufosinate is an effective option to manage Italian ryegrass. However, the glufosinate-resistant biotypes documented in Oregon may jeopardize this practice. Non-chemical weed control options are needed for sustainable weed management in hazelnuts.


2019 ◽  
Vol 34 (4) ◽  
pp. 498-505
Author(s):  
Tameka L. Sanders ◽  
Jason A. Bond ◽  
Benjamin H. Lawrence ◽  
Bobby R. Golden ◽  
Thomas W. Allen ◽  
...  

AbstractRice with enhanced tolerance to herbicides that inhibit acetyl coA carboxylase (ACCase) allows POST application of quizalofop, an ACCase-inhibiting herbicide. Two concurrent field studies were conducted in 2017 and 2018 near Stoneville, MS, to evaluate control of grass (Grass Study) and broadleaf (Broadleaf Study) weeds with sequential applications of quizalofop alone and in mixtures with auxinic herbicides applied in the first or second application. Sequential treatments of quizalofop were applied at 119 g ai ha−1 alone and in mixtures with labeled rates of auxinic herbicides to rice at the two- to three-leaf (EPOST) or four-leaf to one-tiller (LPOST) growth stages. In the Grass Study, no differences in rice injury or control of volunteer rice (‘CL151’ and ‘Rex’) were detected 14 and 28 d after last application (DA-LPOST). Barnyardgrass control at 14 and 28 DA-LPOST with quizalofop applied alone or with auxinic herbicides EPOST was ≥93% for all auxinic herbicide treatments except penoxsulam plus triclopyr. Barnyardgrass control was ≥96% with quizalofop applied alone and with auxinic herbicides LPOST. In the Broadleaf Study, quizalofop plus florpyrauxifen-benzyl controlled more Palmer amaranth 14 DA-LPOST than other mixtures with auxinic herbicides, and control with this treatment was greater EPOST compared with LPOST. Hemp sesbania control 14 DA-LPOST was ≤90% with quizalofop plus quinclorac LPOST, orthosulfamuron plus quinclorac LPOST, and triclopyr EPOST or LPOST. All mixtures except quinclorac and orthosulfamuron plus quinclorac LPOST controlled ivyleaf morningglory ≥91% 14 DA-LPOST. Florpyrauxifen-benzyl or triclopyr were required for volunteer soybean control >63% 14 DA-LPOST. To optimize barnyardgrass control and rice yield, penoxsulam plus triclopyr and orthosulfamuron plus quinclorac should not be mixed with quizalofop. Quizalofop mixtures with auxinic herbicides are safe and effective for controlling barnyardgrass, volunteer rice, and broadleaf weeds in ACCase-resistant rice, and the choice of herbicide mixture could be adjusted based on weed spectrum in the treated field.


1997 ◽  
Vol 11 (3) ◽  
pp. 602-607 ◽  
Author(s):  
Eric Spandl ◽  
Thomas L. Rabaey ◽  
James J. Kells ◽  
R. Gordon Harvey

Optimal application timing for dicamba–acetamide tank mixes was examined in field studies conducted in Michigan and Wisconsin from 1993 to 1995. Dicamba was tank mixed with alachlor, metolachlor, or SAN 582H and applied at planting, 7 d after planting, and 14 d after planting. Additional dicamba plus alachlor tank mixes applied at all three timings were followed by nicosulfuron postemergence to determine the effects of noncontrolled grass weeds on corn yield. Delaying application of dicamba–acetamide tank mixes until 14 d after planting often resulted in lower and less consistent giant foxtail control compared with applications at planting or 7 d after planting. Corn grain yield was reduced at one site where giant foxtail control was lower when application was delayed until 14 d after planting. Common lambsquarters control was excellent with 7 or 14 d after planting applications. At one site, common lambsquarters control and corn yield was reduced by application at planting. Dicamba–alachlor tank mixes applied 7 d after planting provided similar weed control or corn yield, while at planting and 14 d after planting applications provided less consistent weed control or corn yield than a sequential alachlor plus dicamba treatment or an atrazine-based program.


2019 ◽  
Vol 34 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Derek M. Whalen ◽  
Lovreet S. Shergill ◽  
Lyle P. Kinne ◽  
Mandy D. Bish ◽  
Kevin W. Bradley

AbstractCover crops have increased in popularity in midwestern U.S. corn and soybean systems in recent years. However, little research has been conducted to evaluate how cover crops and residual herbicides are effectively integrated together for weed control in a soybean production system. Field studies were conducted in 2016 and 2017 to evaluate summer annual weed control and to determine the effect of cover crop biomass on residual herbicide reaching the soil. The herbicide treatments consisted of preplant (PP) applications of glyphosate plus 2,4-D with or without sulfentrazone plus chlorimuron at two different timings, 21 and 7 d prior to soybean planting (DPP). Cover crops evaluated included winter vetch, cereal rye, Italian ryegrass, oat, Austrian winter pea, winter wheat, and a winter vetch plus cereal rye mixture. Herbicide treatments were applied to tilled and nontilled soil without cover crop for comparison. The tillage treatment resulted in low weed biomass at all collection intervals after both application timings, which corresponded to tilled soil having the highest sulfentrazone concentration (171 ng g−1) compared with all cover crop treatments. When applied PP, herbicide treatments applied 21 DPP with sulfentrazone had greater weed (93%) and waterhemp (89%) control than when applied 7 DPP (60% and 69%, respectively). When applied POST, herbicide treatments with a residual herbicide resulted in greater weed and waterhemp control at 7 DPP (83% and 77%, respectively) than at 21 DPP (74% and 61%, respectively). Herbicide programs that included a residual herbicide had the highest soybean yields (≥3,403 kg ha−1). Results from this study indicate that residual herbicides can be effectively integrated either PP or POST in conjunction with cover crop termination applications, but termination timing and biomass accumulation will affect the amount of sulfentrazone reaching the soil.


2008 ◽  
Vol 22 (4) ◽  
pp. 584-590 ◽  
Author(s):  
Wilson H. Faircloth ◽  
Jason A. Ferrell ◽  
Christopher L. Main

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


1997 ◽  
Vol 11 (4) ◽  
pp. 708-713 ◽  
Author(s):  
W. James Grichar

Field studies were conducted from 1992 through 1994 to evaluate application timing of seven postemergence (POST) broadleaf herbicides alone and in mixtures for control of eclipta and pitted morningglory. Imazethapyr and 2,4-DB did not control eclipta while AC 263,222 applied early postemergence (EPOST) at 0.07 kg/ha provided greater than 90% control in 2 of 3 yr. EPOST applications of bentazon, acifluorfen + bentazon, and pyridate controlled eclipta at least 92% all 3 yr. Lactofen applied EPOST at 0.28 kg/ha provided similar levels of eclipta control in 2 of 3 yr. Imazethapyr controlled pitted morningglory > 70% when applied EPOST. AC 263,222 controlled pitted morningglory a minimum of 83% when applied EPOST at 0.04 or 0.07 kg/ha. Pitted morningglory control was at least 85% with 2,4-DB applied alone or in a mixture with AC 263,222, acifluorfen, imazethapyr, lactofen, or pyridate. Effective weed control increased peanut yields up to 98% over the untreated check.


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