Annual weed competitiveness as affected by preemergence herbicide in corn

Weed Science ◽  
2006 ◽  
Vol 54 (1) ◽  
pp. 156-165 ◽  
Author(s):  
Konanani B. Liphadzi ◽  
J. Anita Dille

Competitiveness of weeds that survive a PRE herbicide application (escaped weeds) might be altered because of herbicide injury. As a result, potential crop yield loss may be reduced. Field experiments were conducted at Ashland Bottoms, KS, in 2001 and 2002 and at Rossville, KS, in 2002. The objectives were to quantify corn growth and yield response to Palmer amaranth or velvetleaf competition, with or without isoxaflutole (0.03 kg ha−1) or flumetsulam (0.04 kg ha−1) application, and to determine seed production of Palmer amaranth or velvetleaf as affected by PRE herbicide. Palmer amaranth and velvetleaf densities ranged from 0 to 6 and 0 to 32 plants m−1of corn row, respectively. At Ashland Bottoms in 2002, corn height at tasseling decreased with increasing Palmer amaranth (1.58 cm weed−1m−1) and velvetleaf (1.32 cm weed−1m−1) density when no herbicide was applied. With flumetsulam application, each increase in velvetleaf density reduced corn height by 0.4 cm. Escaped Palmer amaranth and velvetleaf were shorter than untreated plants at corn tasseling. At Rossville in 2002, Palmer amaranth that escaped isoxaflutole or flumetsulam application caused 13% corn yield loss (YL) at a density of 3 plants m−1. In contrast, corn YL from untreated Palmer amaranth at the same density was 30%. At Ashland Bottoms in 2002, velvetleaf that escaped flumetsulam caused 3% corn YL at a density of 3 plants m−1compared with 38% YL caused by untreated velvetleaf at the same density. Seed production of Palmer amaranth was independent of density or herbicide treatment, whereas production of velvetleaf seed increased with density, with or without flumetsulam. The study showed that corn YL from both Palmer amaranth and velvetleaf that escaped a PRE herbicide was less than from untreated weeds, but seed production by escaped weeds was similar to that of untreated weeds.

Weed Science ◽  
2013 ◽  
Vol 61 (2) ◽  
pp. 249-258 ◽  
Author(s):  
Ella K. Ruf-Pachta ◽  
Dwain M. Rule ◽  
J. Anita Dille

Palmer amaranth influences selection of crop production practices such as irrigation, nitrogen (N) application, and weed control. The objectives of this research were to determine if Palmer amaranth was more responsive to applied N than corn and if this differed under dryland and irrigated conditions in Kansas. Field experiments were conducted near Manhattan, KS, in 2005 and 2006 to evaluate the influence of N rate and Palmer amaranth densities when grown with corn in two soil moisture environments. A very drought-stressed environment and a well-watered environment occurred in 2006, while both environments in 2005 were intermediate. Dryland weed-free corn yields were 46.5% of irrigated corn yields at the high N rate across years. Irrigated corn yields responded to increasing N rates. In the presence of Palmer amaranth, parameter estimates I and A for the yield loss relationship were not different across N rates for each environment and year except 2006 where 100% yield loss was estimated in dryland compared to 62.5% loss in irrigated environment at high N rates. In three of four environment-years, N rate did not affect the corn yield loss relationship with weed density. In 2006 irrigated environment, greater N rates had less corn yield loss caused by Palmer amaranth. By corn anthesis, weed-free corn biomass was 167.5% greater in irrigated than dryland environments in 2006. Palmer amaranth with no corn increased its biomass by 373 and 361% as N rate increased in 2005 and 2006, respectively. Nitrogen concentrations in plant tissues of corn or weed increased similarly as N rates increased from 0 to 224 kg N ha−1, thus highlighting that both corn and Palmer amaranth responded similarly to increasing N. In general, soil moisture environment was most critical when determining potential corn yield, followed by Palmer amaranth density and N rate.


2009 ◽  
Vol 23 (4) ◽  
pp. 503-506 ◽  
Author(s):  
John D. Everitt ◽  
J. Wayne Keeling

Field experiments were conducted in Hale Co., TX, in 2005 and 2006 to determine the effects of 2,4-D amine and dicamba applied at varying rates and growth stages on cotton growth and yield, and to correlate cotton injury levels and lint yield reductions. Dicamba or 2,4-D amine was applied at four growth stages including cotyledon to two-leaf, four- to five-leaf, pinhead square, and early bloom. Dicamba and 2,4-D amine were applied at 1/2, 1/20, 1/200, and 1/2000 of the recommended use rate. Crop injury was recorded at 14 days after treatments and late-season, and cotton lint yields were determined. Across all growth stages, 2,4-D caused more crop injury and yield loss than dicamba. Cotton lint was reduced more by later applications (especially pinhead square) and injury underestimated yield loss with 2,4-D. Visual estimates of injury overestimated yield loss when 2,4-D or dicamba was applied early (cotyledon to two leaf) and was not a good predictor of yield loss.


1995 ◽  
Vol 9 (1) ◽  
pp. 91-98 ◽  
Author(s):  
K. Neil Harker ◽  
Robert E. Blackshaw ◽  
Ken J. Kirkland

Field experiments were conducted from 1986 to 1988 at Lacombe and Lethbridge, Alberta and Scott, Saskatchewan to determine growth and yield response of canola to mixtures of ethametsulfuron with specific grass herbicides. Ethametsulfuron did not usually cause canola injury when mixed with sethoxydim. However, ethametsulfuron mixtures with the following grass herbicides listed in decreasing order of injury potential, often caused canola injury and yield loss: haloxyfop > fluazifop > fluazifop-P > quizalofop > quizalofop-P. Canola yield losses were severe in some experiments, ranging from 59% with quizalofop mixtures to 97% with haloxyfop mixtures; in other experiments, the same mixtures did not cause significant yield losses. ‘Tobin,’ aBrassica rapacultivar, tended to be more susceptible to injury than theB. napuscultivars ‘Pivot’ and ‘Westar.’ Canola injury symptoms were consistent with those expected from sulfonylurea herbicides. Therefore, we suggest that specific grass herbicides differentially impair the ability of canola to metabolize ethametsulfuron to inactive forms.


2018 ◽  
Vol 32 (4) ◽  
pp. 431-438 ◽  
Author(s):  
Xiao Li ◽  
Timothy Grey ◽  
William Vencill ◽  
James Freeman ◽  
Katilyn Price ◽  
...  

AbstractFomesafen provides effective control of glyphosate-resistant Palmer amaranth in cotton. However, cotton seedlings can be injured when fomesafen is applied PRE. Therefore, greenhouse and field experiments were conducted at Athens, GA, and at six locations in Alabama and Georgia in 2013 and 2016 to evaluate cotton growth and yield response to fomesafen applied PRE at 70, 140, 280, 560, 1,120, or 2,240 g ai ha−1, and in combination with pendimethalin, diuron, acetochlor, and fluridone at 1×label rates. Greenhouse bioassays indicated that fomesafen reduced cotton height and dry weight with increasing rate in Cecil sandy loam and Tifton loamy sand but not in Greenville sandy clay loam––possibly as a result of this soil’s higher organic matter (OM) and clay content. Fomesafen applied at 2,240 g ai ha−1 reduced cotton stand by as much as 83% compared to the nontreated check (NTC) at all field locations except Alabama’s Macon and Baldwin counties, and 1,120 g ai ha−1 reduced cotton stand only at Pulaski County, GA, by 52%. Cotton height was reduced by the two highest rates of fomesafen at all locations except Clarke County, GA, and Baldwin County, AL. Injury data indicated more visual injury followed increasing fomesafen rates, and high-rate treatments produced more injury in sandier soils. Cotton yield was unaffected by herbicide treatments at any location, except for the 1,120 g ai ha−1 rate at Pulaski County (49% yield loss compared to NTC), 2,240 g ai ha−1 at Pulaski County (72% yield loss), and Tift County (29% yield loss). These data indicated cotton yield should not be negatively affected by fomesafen applied PRE alone within label rates or in combination with pendimethalin, diuron, acetochlor, and fluridone at 1×label rates, although some visual injury, or stand or height reduction may occur early in the growing season.


Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 491-496 ◽  
Author(s):  
Brescia R. M. Terra ◽  
Alexander R. Martin ◽  
John L. Lindquist

Injury to weeds from sublethal doses of POST herbicides may reduce the effect of weed interference on crop yield. Information on how herbicide dose influences weed mortality, growth, and seed production is needed to assess the potential benefit of applying reduced herbicide doses. Field experiments were conducted at Mead, NE, in 2001 and 2002 to quantify velvetleaf mortality, growth, and corn–velvetleaf interference in response to varying doses of three POST herbicides. Untreated velvetleaf at six densities (0, 1, 3, 6, 12, and 20 plants m−1 corn row) was grown in mixture with corn to establish a baseline corn–velvetleaf interference relationship. Treated velvetleaf at a density of 20 plants m−1 row received one of five doses of dicamba, halosulfuron, or flumiclorac. Untreated velvetleaf height, biomass, and seed capsule production were greater in 2002 than 2001 and declined with increasing velvetleaf density in both years. Corn yield was not affected by untreated velvetleaf in 2001, but yield loss increased with increasing velvetleaf density in 2002. Mortality of herbicide-treated velvetleaf was 56% greater in 2001 than 2002 and increased with increasing herbicide dose. Maximum height of treated velvetleaf was similar for all treatments in 2001 but declined with increasing herbicide dose in 2002. Biomass and seed production of treated velvetleaf varied among herbicides in 2002 and decreased with increasing dose. Corn yield was not influenced by velvetleaf in 2001, but yield loss in response to herbicide-treated velvetleaf declined with increasing herbicide dose in 2002. Results show that the assumption that weeds surviving herbicide application are as competitive as untreated weeds is incorrect. Reduction in growth and resource consumption by herbicide-damaged weeds reduced the negative effects of weeds on corn.


Weed Science ◽  
2020 ◽  
Vol 68 (5) ◽  
pp. 467-475
Author(s):  
Nicholas E. Korres ◽  
Jason K. Norsworthy ◽  
Andy Mauromoustakos ◽  
Martin M. Williams

AbstractKnowledge of crop–weed interference effects on weed biology along with yield penalties can be used for the development of integrated weed management (IWM) tactics. Nevertheless, little is known about the beneficial effects of soybean [Glycine max (L.) Merr.] density, an important aspect of IWM, on late Palmer amaranth (Amaranthus palmeri S. Watson) establishment time. Two field experiments were conducted in 2014 and 2015 to investigate how various soybean densities and A. palmeri establishment timings in weeks after crop emergence (WAE) affect height, biomass, and seed production of the weed but also crop yield in drill-seeded soybean. Soybean density had a significant impact on dry weight and seed production of A. palmeri that established within the first 2 wk of crop emergence, but not for establishment timings of the weed 4 wk and later in relation to crop emergence. Differential performance of A. palmeri gender was observed, regarding greater biomass production of female than male plants under crop presence, and merits further investigation. Grain yield reductions were recorded at earlier A. palmeri establishment timings (i.e., 0 and 1 WAE) compared with 8 WAE establishment timing in 2014 and 2015. High soybean densities resulted in greater soybean yields compared with low soybean density, but no grain yield benefits were observed between medium and high soybean densities. Crop budget analysis revealed the benefits of moderate seeding rate (i.e., 250, 000 seeds ha−1) increases in comparison to lower (i.e., 125,000 seeds ha−1) or high (i.e., 400,000 seeds ha−1) on crop revenue, net income returns, and breakeven price. Earlier A. palmeri establishment timings (i.e., 0, 1, and 2 WAE) resulted in lower crop revenue and net income returns compared with later establishment timings of the weed.


Weed Science ◽  
1997 ◽  
Vol 45 (2) ◽  
pp. 276-282 ◽  
Author(s):  
Aca C. Bosnic ◽  
Clarence J. Swanton

Barnyardgrass is a serious weed problem in cornfields in Ontario. Field experiments were conducted at two locations in 1994 and 1995 to determine the influence of emergence time and barnyardgrass density on corn yield loss, leaf area at 50% silking, and barnyardgrass seed production. Selected barnyardgrass densities up to 200 plants m−1were established within 12.5 cm on either side of the corn row. Barnyardgrass seeds were planted concurrently with corn and at the 3- to 5- or 1- to 2-leaf stage of corn growth in 1994 and 1995, respectively. Barnyardgrass density and seedling emergence relative to corn influenced the magnitude of corn yield loss. Maximum corn grain yield loss ranged from 26 to 35% for early emerging barnyardgrass, and less than 6% yield loss occurred from barnyardgrass seedlings emerging later than the 4-leaf stage of corn growth. Changes in corn leaf area index at 50% silking reflected the level of barnyardgrass competition in corn. Maximum leaf area reduction ranged from 21 to 23%. Barnyardgrass seed production varied with time of seedling emergence and density. Ten barnyardgrass plants emerging up to the 3-leaf stage of corn growth produced 14,400 to 34,600 seeds m−2compared to only 1,200 to 2,800 seeds m−2from plants emerging after the 4-leaf corn stage. The results of this study are essential in the development of an integrated weed management strategy for corn.


Weed Science ◽  
2006 ◽  
Vol 54 (02) ◽  
pp. 354-363 ◽  
Author(s):  
Darren C. Barker ◽  
Stevan Z. Knezevic ◽  
Alex R. Martin ◽  
Daniel T. Walters ◽  
John L. Lindquist

Weeds that respond more to nitrogen fertilizer than crops may be more competitive under high nitrogen (N) conditions. Therefore, understanding the effects of nitrogen on crop and weed growth and competition is critical. Field experiments were conducted at two locations in 1999 and 2000 to determine the influence of varying levels of N addition on corn and velvetleaf height, leaf area, biomass accumulation, and yield. Nitrogen addition increased corn and velvetleaf height by a maximum of 15 and 68%, respectively. N addition increased corn and velvetleaf maximum leaf area index (LAI) by up to 51 and 90%. Corn and velvetleaf maximum biomass increased by up to 68 and 89% with N addition. Competition from corn had the greatest effect on velvetleaf growth, reducing its biomass by up to 90% compared with monoculture velvetleaf. Corn response to N addition was less than that of velvetleaf, indicating that velvetleaf may be most competitive at high levels of nitrogen and least competitive when nitrogen levels are low. Corn yield declined with increasing velvetleaf interference at all levels of N addition. However, corn yield loss due to velvetleaf interference was similar across N treatments except in one site–year, where yield loss increased with increasing N addition. Corn yield loss due to velvetleaf interference may increase with increasing N supply when velvetleaf emergence and early season growth are similar to that of corn.


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