Reduced Rates of Postemergence Herbicides for Weed Control in Sweet Corn (Zea mays)

1993 ◽  
Vol 7 (4) ◽  
pp. 995-1000 ◽  
Author(s):  
John O'Sullivan ◽  
William J. Bouw

The efficacy of reduced rates of POST herbicides for weed control in sweet corn was evaluated over a three-year period in field studies conducted at the Horticultural Experiment Station, Simcoe, Ontario. POST applications of metolachlor/cyanazine, cyanazine/atrazine and metolachlor/atrazine at 1/2X and 1/4X of labelled rates controlled broadleaf weeds comparable to that of standard labelled rates. Control exceeded 94% each year. Annual grass control was reduced with below-label rates, especially for cyanazine/atrazine and metolachlor/atrazine. A 1/2X application of nicosulfuron/rimsulfuron, following the 1/4X rate of cyanazine/atrazine, significantly improved grass control, compared to cyanazine/atrazine applied alone. Below-label rates did not result in decreased sweet corn yields.

1995 ◽  
Vol 9 (4) ◽  
pp. 728-735 ◽  
Author(s):  
Robert J. Parks ◽  
William S. Curran ◽  
Gregory W. Roth ◽  
Nathan L. Hartwig ◽  
Dennis D. Calvin

Greenhouse studies assessed the susceptibility of three common lambsquarters biotypes to foliar-applied bromoxynil, dicamba, and thifensulfuron. Field studies evaluated the effectiveness of the same herbicides in conjunction with atrazine and row cultivation for the control of common lambsquarters in corn. In the field, bromoxynil was applied at 140, 280, and 420 g/ha, dicamba at 140, 280, and 560 g/ha, and thifensulfuron at 2, 3, and 4 g/ha. In the greenhouse, bromoxynil and thifensulfuron reduced common lambsquarters growth by at least 55%, while dicamba reduced growth 45% or less. Two of the three biotypes were resistant to atrazine. In the field, weed control was up to 70% better in cultivated plots than in noncultivated plots. Cultivation sometimes promoted additional weed emergence, but later emerging weeds rarely reached reproductive maturity. Atrazine improved the level of weed control only if triazine-susceptible weeds were present. The lowest rates of bromoxynil and dicamba (140 g/ha) controlled common lambsquarters 85% or greater even without cultivation, whereas control with the low rate of thifensulfuron (2 g/ha) was acceptable (greater than 85%) 8 wk after planting only in combination with cultivation. Combinations of reduced herbicide rates and mechanical cultivation provided effective, alternative control strategies for both triazine-resistant and susceptible common lambsquarters.


2014 ◽  
Vol 28 (2) ◽  
pp. 371-376
Author(s):  
O. Steven Norberg ◽  
Joel Felix

Teff is a warm-season C4 annual grass crop grown for forage and food grain that has recently increased in production in parts of the United States. Hay from teff is well suited for livestock, especially horses. The objective of this study was to evaluate teff and weed response to selected herbicides in field studies conducted at the Malheur Experiment Station, Ontario, OR in 2009 and 2010. Herbicides were applied POST when teff was at the four-leaf stage. Broadleaf weed control at 21 d after treatment was greater than 91% across herbicide treatments. Only the premix of 2.5 g ai ha−1florasulam + 99 g ae ha−1fluroxypyr + 15 g ai ha−1pyroxsulam provided acceptable control of barnyardgrass. Due primarily to barnyardgrass competition, teff treated with a premix of 2.5 g ha−1florasulam + 99 g ha−1fluroxypyr + 15 g ha−1pyroxsulam produced 7,200 kg ha−1of teff hay compared with 4,800 kg ha−1of teff hay for 2,4-D and dicamba and 4,200 kg ha−1teff hay when no herbicides were used. Teff grain production was greater with 2.5 g ha−1florasulam + 99 g ha−1fluroxypyr + 15 g ha−1pyroxsulam compared with any of the other treatments. The use of a premix of florasulam + fluroxypyr + pyroxsulam would improve broadleaf and grass weed control in ‘Tiffany' and ‘Dessie' teff varieties, improve hay and grain yield, and reduce production costs.


2005 ◽  
Vol 85 (1) ◽  
pp. 285-289
Author(s):  
J. O’Sullivan ◽  
P. H. Sikkema

Field studies were conducted in 1999 and 2000 at Simcoe and Exeter, Ontario to determine the effect of glufosinate, applied alone or in combination with s-metolachlor/atrazine, on weed control and crop safety on six glufosinate-resistant Bt sweet corn cultivars. A single application of glufosinate at 0.5 or 1.0 kg ha-1 gave 89% or better control of redroot pigweed, common ragweed, wild buckwheat and lady’s-thumb in 1999 and pale smartweed and redroot pigweed in 2000. Glufosinate applied alone gave reduced control of wild buckwheat and barnyard grass in 2000 and reduced control of crab grass in 1999 and 2000 at Simcoe. S-metolachlor/atrazine applied preemergence, followed by glufosinate postemergence, improved control of these species. In the untreated control, yield of all cultivars, except Bonus Bt at Exeter, was reduced at all locations. Yield of Cupola Bt and SS Jubilee Bt was reduced when glufosinate was applied alone at 0.5 kg ha-1. Yield of Cupola Bt, Empire Bt and SS Jubilee Bt was reduced with s-metolachlor/atrazine used alone. Maximum yields were obtained with a sequential treatment of s-metolachlor/atrazine followed by glufosinate. Glufosinate did not cause any injury, plant height reduction or delayed maturity of any glufosinate-resistant Bt sweet corn cultivars. Key words: Cultivar, sensitivity, herbicide injury, glufosinate, Zea mays


Weed Science ◽  
1993 ◽  
Vol 41 (2) ◽  
pp. 213-217 ◽  
Author(s):  
Peter A. Dotray ◽  
Lorelei C. Marshall ◽  
William B. Parker ◽  
Donald L. Wyse ◽  
David A. Somers ◽  
...  

Homozygous, sethoxydim-tolerant corn was field tested at two locations in 1989 and 1990. Sethoxydim at 0.22, 0.44, and 0.88 kg ha−1was applied to sethoxydimtolerant corn in the 3- and 7-leaf stages. None of the sethoxydim treatments caused visible injury to the sethoxydim-tolerant corn, but all treatments were lethal to a parental corn line used as a control. Sethoxydim applied at either stage of corn development had no effect on number of days to 50% silk emergence, plant height, or grain yield, compared to nontreated plants. Sethoxydim-tolerant corn was also tolerant to mixtures of sethoxydim plus other postemergence herbicides that control dicotyledonous weeds. Sethoxydim mixed with atrazine or sethoxydim applied in sequential applications with dicamba or 2,4-D gave annual grass control similar to sethoxydim applied alone. However, the sethoxydim plus bentazon treatment resulted in reduced grass control in comparison to sethoxydim alone. When the broadleaf herbicides were mixed with sethoxydim or applied as sequential treatments, broadleaf weed control was the same as when the broadleaf herbicides were applied alone. The high level of corn tolerance to sethoxydim and the broad spectrum of weed control resulting from combinations of sethoxydim plus other postemergence herbicides indicates that sethoxydim-tolerant corn hybrids could increase the options available for weed control in corn.


1990 ◽  
Vol 4 (3) ◽  
pp. 631-634 ◽  
Author(s):  
R. E. Blackshaw

Field studies were conducted in 1987, 1988, and 1989 at Lethbridge, Alberta to determine suitable herbicides for the control of Russian thistle and kochia in field corn grown in a dryland cropping system. Soil-applied atrazine or cyanazine provided inconsistent control of these weeds under dryland conditions. Combining inter-row tillage or 2,4-D applied postemergence with soil-applied atrazine improved the consistency of weed control over years. Postemergence atrazine and dicamba plus 2,4-D controlled Russian thistle and kochia in all years. Corn yields reflected the level of weed control attained with each treatment. The suitability of the various treatments for weed control in corn grown under dryland crop production systems is discussed.


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.


1999 ◽  
Vol 13 (3) ◽  
pp. 484-488 ◽  
Author(s):  
John W. Wilcut ◽  
John S. Richburg ◽  
F. Robert Walls

Field studies were conducted in 1992 and 1993 to evaluate AC 263,222 applied postemergence (POST) alone and as a mixture with atrazine or bentazon for weed control in imidazolinone-resistant corn. Nicosulfuron alone and nicosulfuron plus atrazine were also evaluated. Herbicide treatments were applied following surface-banded applications of two insecticides, carbofuran or terbufos at planting. Crop sensitivity to POST herbicides, corn yield, and weed control was not affected by insecticide treatments. AC 263,222 at 36 and 72 g ai/ha controlled rhizomatous johnsongrass 88 and 99%, respectively, which was equivalent to nicosulfuron applied alone or with atrazine. AC 263,222 at 72 g/ha controlled large crabgrass 99% and redroot pigweed 100%, and this level of control exceeded that obtained with nicosulfuron alone. AC 263,222 at 72 g/ha controlled sicklepod and morningglory species 99 and 98%, respectively. Nicosulfuron alone or with atrazine controlled these two species less than AC 263,222 at 72 g/ha. Addition of bentazon or atrazine to AC 263,222 did not improve control of any species compared with the higher rate of AC 263,222 at 72 g/ha applied alone. Corn yield increased over the untreated control when POST herbicide(s) were applied, but there were no differences in yield among herbicide treatments.


1994 ◽  
Vol 8 (4) ◽  
pp. 673-678 ◽  
Author(s):  
David A. Wall

Field studies were undertaken in 1992 and 1993 to investigate the control of wild oat and green foxtail in flax with reduced rates of fluazifop-P and clethodim applied as tank-mixtures. Fluazifop-P plus clethodim at 50 + 18 g ai/ha controlled wild oat and green foxtail and was as effective as full rates of either herbicide applied alone. These rates represent a 20% reduction in total amount of active ingredient required to control wild oat and green foxtail. Application of fluazifop-P, and/or clethodim prior to the 3- to 4-leaf stage failed to control late emerging grass weeds. Application of graminicide mixtures at or after the 3- to 4-leaf stage controlled late emerging grass weeds and did not affect flax yield. When applied late, fluazifop-P at 175 g/ha tended to reduce flax yield, although weed control was acceptable and no foliar injury was observed following treatment. The efficacy of graminicide mixtures was reduced by addition of bromoxynil plus MCPA to the spray mix.


1998 ◽  
Vol 12 (4) ◽  
pp. 631-637 ◽  
Author(s):  
Corey V. Ransom ◽  
James J. Kells

Field studies were conducted from 1994 to 1996 in Michigan to evaluate postemergence (POST) herbicides for hemp dogbane control in corn. Studies were initiated at no-tillage and chisel-plowed sites each of the three years. Nicosulfuron and primisulfuron were evaluated alone and in combination with 2,4-D amine or dicamba. In 1995 and 1996, CGA-152005 plus primisulfuron was also applied alone and in combination with 2,4-D or dicamba. Control varied among years and sites. Nicosulfuron, primisulfuron, and CGA-152005 plus primisulfuron applied alone controlled 30% of the hemp dogbane, and dicamba or 2,4-D alone controlled 42 and 66%, respectively. Tank mixtures of nicosulfuron, primisulfuron, or CGA-152005 plus primisulfuron with dicamba were more effective and more consistent than dicamba alone. Combinations of nicosulfuron, primisulfuron, or CGA-152005 plus primisulfuron with 2,4-D gave the most effective and consistent control across sites, with an average of 93% control. In general, treatments controlled only shoots that had emerged at the time of application. New shoots emerged following herbicide application at the chisel-tillage sites in 1994 and 1995 but not at the no-tillage sites. However, in 1996, shoot emergence following treatment occurred in both no-tillage and chisel-tillage sites.


Weed Science ◽  
1980 ◽  
Vol 28 (6) ◽  
pp. 719-722 ◽  
Author(s):  
J. J. Kells ◽  
R. L. Blevins ◽  
C. E. Rieck ◽  
W. M. Muir

Field studies were conducted to determine the effect of soil surface (upper 5 cm) pH and tillage on weed control and corn (Zea maysL.) yield using simazine [2-chloro-4,6-bis-(ethylamino)-s-triazine] as the herbicide for weed control. Soil pH, weed control, and corn yield were examined under no-tillage and conventional tillage systems with and without added lime and different rates of nitrogen. Increased soil pH significantly increased weed control as compared with added lime vs. no added lime, where the surface soil pH influenced the effectiveness of the applied simazine. Soil pH had a greater effect on weed control under no-tillage than under conventional tillage. Conventional tillage significantly (P<.01) increased weed control, yield, and soil pH over no-tillage. Additions of lime as compared to unlimed treatments resulted in significantly increased weed control (83% vs. 63%), yield (5,930 vs. 5,290 kg/ha) and soil pH (5.91 vs. 5.22). The poorest weed control was observed with no-tillage on unlimed plots. A significant tillage by linear effect of nitrogen interaction for all variables resulted from a greater decrease (P<.01) in weed control and soil pH and a greater increase in yield with increased nitrogen under no-tillage than with conventional tillage.


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