Response of Non–Dicamba-Resistant Soybean to Dicamba As Influenced by Growth Stage and Herbicide Rate

2018 ◽  
Vol 32 (5) ◽  
pp. 513-519 ◽  
Author(s):  
Spencer McCown ◽  
Tom Barber ◽  
Jason K. Norsworthy

AbstractIntroduction of the Roundup Ready® Xtend system (Monsanto Co., St. Louis, MO) provides an alternative weed management option for growers, but of concern is the risk of dicamba injury to sensitive crops, particularly soybean from off-target movement and tank contamination. Experiments were conducted to determine the response of soybean to low rates of dicamba over a wide range of application timings. Two glufosinate-resistant varieties (HBK 4950LL–indeterminate and HALO 5.45LL–determinate) commonly grown in Arkansas were chosen for these studies. Two rates of dicamba, 2.18 and 8.75 g ae ha–1(1/256× and 1/64× of the POST labeled rate for dicamba-resistant soybean), were applied at two vegetative (V4, V6) and six reproductive (R1 to R6) growth stages. Compared to the nontreated control, dicamba applied during late vegetative and early reproductive growth of soybean caused leaf injury, plant height reduction, and seed yield loss for both soybean cultivars. Averaged across dicamba rates applied at R1, soybean seed yield was reduced 14% for the HBK 4950LL cultivar and 19% for the HALO 5.45LL cultivar. Averaged over rates, dicamba applied at R1 to the HALO 5.45LL and HBK 4950LL soybean resulted in 48% and 43% visible injury 4 wk after treatment, respectively. Grain yield was similar to that of the nontreated control when dicamba was applied at the later reproductive stages averaged across rates.

2016 ◽  
Vol 96 (1) ◽  
pp. 160-164 ◽  
Author(s):  
Nader Soltani ◽  
Robert E. Nurse ◽  
Peter H. Sikkema

The anticipated availability of dicamba-resistant crops will increase the potential for crop injury to non-dicamba-resistant soybean due to dicamba spray tank contamination. A total of eight field trials were conducted at various locations in Ontario, Canada during 2012–2014 to determine the response of non-dicamba-resistant soybean to dicamba spray tank contamination at 0, 0.75, 1.5, 3, 6, 15, 30, and 60 g a.e. ha−1 applied postemergence (POST) at the V2-3 (2–3 trifoliate) or R1 (1st flower) stage. At one week after treatment (WAT), dicamba applied at 0.75, 1.5, 3, 6, 15, 30, and 60 g a.e. ha−1 at V2-3 caused 12, 18, 25, 31, 43, 53, and 66% visible injury in soybean, respectively. Injury increased at 2 and 4 WAT and decreased by 8 WAT with 68% visible injury observed at the highest dose. Dicamba applied at R1 caused 23, 28, 36, 40, 48, 61, and 73% visible injury in soybean at 0.75, 1.5, 3, 6, 15, 30, and 60 g a.e. ha−1, respectively. The predicted dose of dicamba to reduce soybean seed yield 1, 5, 10, 20 or 50% was 1.1, 5.8, 11.8, 25.2, and >60 g a.e. ha−1 when applied at V2-3 and <0.75, 1.0, 2.0, 4.3, and 11.5 g a.e. ha−1 when applied at R1, respectively. Results show that dicamba spray tank contamination of as little as 0.75 g a.e. ha−1 can cause significant crop injury in non-dicamba-resistant soybean when applied during the vegetative or reproductive stages.


2019 ◽  
Vol 33 (04) ◽  
pp. 555-561 ◽  
Author(s):  
Alanna B. Scholtes ◽  
Benjamin P. Sperry ◽  
Daniel B. Reynolds ◽  
J. Trenton Irby ◽  
Thomas W. Eubank ◽  
...  

AbstractField experiments were conducted in 2012 and 2013 across four locations for a total of 6 site-years in the midsouthern United States to determine the effect of growth stage at exposure on soybean sensitivity to sublethal rates of dicamba (8.8 g ae ha−1) and 2,4-D (140 g ae ha−1). Regression analysis revealed that soybean was most susceptible to injury from 2,4-D when exposed between 413 and 1,391 accumulated growing degree days (GDD) from planting, approximately between V1 and R2 growth stages. In terms of terminal plant height, soybean was most susceptible to 2,4-D between 448 and 1,719 GDD, or from V1 to R4. However, maximum susceptibility to 2,4-D was only between 624 and 1,001 GDD or from V3 to V5 for yield loss. As expected, soybean was sensitive to dicamba for longer spans of time, ranging from 0 to 1,162 GDD for visible injury or from emergence to R2. Likewise, soybean height was most affected when dicamba exposure occurred between 847 and 1,276 GDD or from V4 to R2. Regarding grain yield, soybean was most susceptible to dicamba between 820 and 1,339 GDD or from V4 to R2. Consequently, these data indicate that soybean response to 2,4-D and dicamba can be variable within vegetative or reproductive growth stages; therefore, specific growth stage at the time of exposure should be considered when evaluating injury from off-target movement. In addition, application of dicamba near susceptible soybean within the V4 to R2 growth stages should be avoided because this is the time of maximum susceptibility. Research regarding soybean sensitivity to 2,4-D and dicamba should focus on multiple exposure times and also avoid generalizing growth stages to vegetative or reproductive.


Weed Science ◽  
2013 ◽  
Vol 61 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Andrew P. Robinson ◽  
Vince M. Davis ◽  
David M. Simpson ◽  
William G. Johnson

Soybean plants exposed POST to 2,4-D can have reduced seed yield depending on the dose and time of exposure, but it is unclear how 2,4-D affects specific yield components. Objectives were to quantify soybean injury, characterize changes in seed yield and yield components of soybean plants exposed to 2,4-D, and determine if seed-yield loss can be estimated from visual assessment of crop injury. Ten rates (0, 0.1, 1.1, 11.2, 35, 70, 140, 280, 560, and 2,240 g ae ha−1) of 2,4-D were applied to Becks brand 342 NRR soybean at three soybean growth stages (V2, V5, or R2). The soybeans were planted near Lafayette, IN and Urbana, IL in 2009 and 2010 and near Fowler, IN in 2009. Twenty percent visual soybean injury was caused by 29 to 109 g ha−12,4-D at 14 d after treatment (DAT) and 109 to 245 g ha−1at 28 DAT. Nonlinear regression models were fit to describe the effect of 2,4-D on seed yield and yield components of soybean. Seed yield was reduced by 5% from 87 to 116 g ha−1and a 10% reduction was caused by 149 to 202 g ha−12,4-D at all application timings. The number of seeds m−2, pods m−2, reproductive nodes m−2, and nodes m−2were the most sensitive yield components. Path analysis indicated that seeds m−2, pods m−2, main stem reproductive nodes m−2, and main stem nodes m−2were the most influential yield components in seed-yield formation. Seed-yield loss was significant (P < 0.0001) and highly correlated (R2= 0.95 to 0.99) to visual soybean injury ratings. A 10% seed-yield loss was caused by 35% soybean injury observed at 14 DAT, whereas a 10% seed-yield loss was a result of 40, 19, and 15% soybean injury observed at 28 DAT when soybean was exposed to 2,4-D at the V2, V5, and R2 growth stages, respectively.


2016 ◽  
Vol 30 (3) ◽  
pp. 629-638 ◽  
Author(s):  
Ti Zhang ◽  
Eric N. Johnson ◽  
Christian J. Willenborg

Desiccants are currently used to improve lentil dry-down prior to harvest. Applying desiccants at growth stages prior to maturity may result in reduced crop yield and quality, and leave unacceptable herbicide residues in seeds. There is little information on whether various herbicides applied alone or as a tank-mix with glyphosate have an effect on glyphosate residues in harvested seed. Field trials were conducted at Saskatoon and Scott, Saskatchewan, Canada, from 2012 to 2014 to determine whether additional desiccants applied alone or tank mixed with glyphosate improve crop desiccation and reduce the potential for unacceptable glyphosate residue in seed. Glufosinate and diquat tank mixed with glyphosate were the most consistent desiccants, providing optimal crop dry-down and a general reduction in glyphosate seed residues without adverse effects on seed yield and weight. Saflufenacil provided good crop desiccation without yield loss, but failed to reduce glyphosate seed residues consistently. Pyraflufen-ethyl and flumioxazin applied alone or tank mixed with glyphosate were found to be inferior options for growers as they exhibited slow and incomplete crop desiccation, and did not decrease glyphosate seed residues. Based on results from this study, growers should apply glufosinate or diquat with preharvest glyphosate to maximize crop and weed desiccation, and minimize glyphosate seed residues.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Walter D. Carciochi ◽  
Luiz H. Moro Rosso ◽  
Mario A. Secchi ◽  
Adalgisa R. Torres ◽  
Seth Naeve ◽  
...  

AbstractIt is unclear if additional inoculation with Bradyrhizobia at varying soybean [Glycine max (L.) Merr.] growth stages can impact biological nitrogen fixation (BNF), increase yield and improve seed composition [protein, oil, and amino acid (AA) concentrations]. The objectives of this study were to evaluate the effect of different soybean inoculation strategies (seed coating and additional soil inoculation at V4 or R1) on: (i) seed yield, (ii) seed composition, and (iii) BNF traits [nodule number and relative abundance of ureides (RAU)]. Soybean field trials were conducted in 11 environments (four states of the US) to evaluate four treatments: (i) control without inoculation, (ii) seed inoculation, (iii) seed inoculation + soil inoculation at V4, and (iv) seed inoculation + soil inoculation at R1. Results demonstrated no effect of seed or additional soil inoculation at V4 or R1 on either soybean seed yield or composition. Also, inoculation strategies produced similar values to the non-inoculated control in terms of nodule number and RAU, a reflection of BNF. Therefore, we conclude that in soils with previous history of soybean and under non-severe stress conditions (e.g. high early-season temperature and/or saturated soils), there is no benefit to implementing additional inoculation on soybean yield and seed composition.


Crop Science ◽  
2017 ◽  
Vol 57 (4) ◽  
pp. 2170-2182 ◽  
Author(s):  
Adam P. Gaspar ◽  
Carrie A.M. Laboski ◽  
Seth L. Naeve ◽  
Shawn P. Conley

2019 ◽  
Vol 33 (04) ◽  
pp. 595-600
Author(s):  
Benjamin P. Sperry ◽  
Benjamin H. Lawrence ◽  
Jason A. Bond ◽  
Daniel B. Reynolds ◽  
Bobby R. Golden ◽  
...  

AbstractResearch was conducted from 2013 to 2015 across three sites in Mississippi to evaluate corn response to sublethal paraquat or fomesafen (105 and 35 g ai ha−1, respectively) applied PRE, or to corn at the V1, V3, V5, V7, or V9 growth stages. Fomesafen injury to corn at three d after treatment (DAT) ranged from 0% to 38%, and declined over time. Compared with the nontreated control (NTC), corn height 14 DAT was reduced approximately 15% due to fomesafen exposure at V5 or V7. Exposure at V1 or V7 resulted in 1,220 and 1,110 kg ha−1 yield losses, respectively, compared with the NTC, but yield losses were not observed at any other growth stage. Fomesafen exposure at any growth stage did not affect corn ear length or number of kernel rows relative to the NTC. Paraquat injury to corn ranged from 26% to 65%, depending on growth stage and evaluation interval. Corn exposure to paraquat at V3 or V5 consistently caused greater injury across evaluation intervals, compared with other growth stages. POST timings of paraquat exposure resulted in corn height reductions of 13% to 50%, except at V7, which was most likely due to rapid internode elongation at that stage. Likewise, yield loss occurred after all exposure times of paraquat except PRE, compared with the NTC. Corn yield was reduced 1,740 to 5,120 kg ha−1 compared with the NTC, generally worsening as exposure time was delayed. Paraquat exposure did not reduce corn ear length, compared with the NTC, at any growth stage. However, paraquat exposure at V3 or V5 was associated with reduction of kernel rows by 1.1 and 1.7, respectively, relative to the NTC. Paraquat and fomesafen applications near corn should be avoided if conditions are conducive for off-target movement, because significant injury and yield loss can result.


2012 ◽  
Vol 26 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Virginia A. Johnson ◽  
Loren R. Fisher ◽  
David L. Jordan ◽  
Keith E. Edmisten ◽  
Alexander M. Stewart ◽  
...  

Development and utilization of dicamba-, glufosinate-, and 2,4-D-resistant crop cultivars will potentially have a significant influence on weed management in the southern United States. However, off-site movement to adjacent nontolerant crops and other plants is a concern in many areas of eastern North Carolina and other portions of the southeastern United States, especially where sensitive crops are grown. Cotton, peanut, and soybean are not resistant to these herbicides, will most likely be grown in proximity, and applicators will need to consider potential adverse effects on nonresistant crops when these herbicides are used. Research was conducted with rates of glufosinate, dicamba, and 2,4-D designed to simulate drift on cotton, peanut, and soybean to determine effects on yield and quality and to test correlations of visual estimates of percent injury with crop yield and a range of growth and quality parameters. Experiments were conducted in North Carolina near Lewiston-Woodville and Rocky Mount during 2009 and 2010. Cotton and peanut (Lewiston-Woodville and Rocky Mount) and soybean (two separate fields [Rocky Mount] during each year were treated with dicamba and the amine formulation of 2,4-D at 1/2, 1/8, 1/32, 1/128, and 1/512 the manufacturer's suggested use rate of 280 g ai ha−1and 540 g ai ha−1, respectively. Glufosinate was applied at rates equivalent to 1/2, 1/4, 1/8, 1/16, and 1/32 the manufacturer's suggested use rate of 604 g ai ha−1. A wide range of visible injury was noted at both 1 and 2 wk after treatment (WAT) for all crops. Crop yield was reduced for most crops when herbicides were applied at the highest rate. Although correlations of injury 1 and 2 WAT with yield were significant (P ≤ 0.05), coefficients ranged from −0.25 to −0.50, −0.36 to −0.62, and −0.40 to −0.67 for injury 1 WAT vs. yield for cotton, peanut, and soybean, respectively. These respective crops had ranges of correlations of −0.17 to −0.43, −0.34 to −0.64, and −0.41 to −0.60 for injury 2 WAT. Results from these experiments will be used to emphasize the need for diligence in application of these herbicides in proximity to crops that are susceptible as well as the need to clean sprayers completely before spraying sensitive crops.


2020 ◽  
pp. 1-5
Author(s):  
Hunter D. Bowman ◽  
Tom Barber ◽  
Jason K. Norsworthy ◽  
Trenton L. Roberts ◽  
Jason Kelley ◽  
...  

Abstract Previous research has shown that glufosinate and nicosulfuron at low rates can cause yield loss to grain sorghum. However, research has not been conducted to pinpoint the growth stage at which these herbicides are most injurious to grain sorghum. Therefore, field tests were conducted in 2016 and 2017 to determine the most sensitive growth stage for grain sorghum exposure to both glufosinate and nicosulfuron. Field test were designed with factor A being the herbicide applied (glufosinate or nicosulfuron). Factor B consisted of timing of herbicide application including V3, V8, flagleaf, heading, and soft dough stages. Factor C was glufosinate or nicosulfuron rate where a proportional rate of 656 g ai ha−1 of glufosinate and 35 g ai ha−1 of nicosulfuron was applied at 1/10×, 1/50×, and 1/250×. Visible injury, crop canopy heights (cm), and yield were reported as a percent of the nontreated. At the V3 growth stage visible injury of 32% from the 1/10× rate of glufosinate and 51% from the 1/10× rate of nicosulfuron was observed. This injury was reduced by 4 wk after application (WAA) and no yield loss occurred. Nicosulfuron was more injurious than glufosinate at a 1/10× and 1/50× rate when applied at the V8 and flagleaf growth stages resulting in death of the shoot, reduced heading, and yield. Yield losses from the 1/10× rate of nicosulfuron were observed from V8 through early heading and ranged from 41% to 96%. Yield losses from the 1/50× rate of nicosulfuron were 14% to 16% at the flagleaf and V8 growth stages respectively. The 1/10× rate of glufosinate caused 36% visible injury 2 WAA when applied at the flagleaf stage, which resulted in a 16% yield reduction. By 4 WAA visible injury from either herbicide at less than the 1/10× rate was not greater than 4%. Results indicate that injury can occur, but yield losses are more probable from low rates of nicosulfuron at V8 and flagleaf growth stages.


Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1171
Author(s):  
Andrzej Brachaczek ◽  
Joanna Kaczmarek ◽  
Malgorzata Jedryczka

Winter oilseed rape (Brassica napus L.) is the main source of domestic oil in central and northern Europe, bringing profits to farmers, but the plants are often damaged by stem canker, caused by two fungal species belonging to the genus Leptosphaeria. Due to environmental concerns, the benefits of fungicide applications must outweigh disadvantages. The aim of this work was to determine the effect of stem canker on seed yield and its quality and find out the best timing of fungicide application. The multi-year field experiments were done at two sites in south-west Poland, where the disease is regarded as a serious problem. The fungicide treatments with the azole-containing preparation followed the same scheme each year; a single application was made at one-week intervals, starting in late September through mid-November for a total of eight treatments. Seed yield, oil and protein content, mass of thousand seeds as well as indole-and alkenyl-glucosinolate contents in seeds were statistically unrelated with the incidence and severity of phoma leaf spotting and stem canker symptoms. The significant decrease of the seed yield was observed in three (site × year combinations) of eight, in which phoma leaf spotting and stem canker were severe. Yield loss was noted only in years with warm and wet autumns, when cumulative mean temperatures between BBCH14 and BBCH19 plant growth stages exceeded 60 °C and precipitation in this period exceeded 110 mm of rain. Under these conditions, fungicide treatments were highly effective when they were done between BBCH15–BBC16 growth stages (5–6 true leaves).


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