Evaluating the double knockdown technique: sequence, application interval, and annual ryegrass growth stage

2007 ◽  
Vol 58 (3) ◽  
pp. 265 ◽  
Author(s):  
Catherine P. Borger ◽  
Abul Hashem
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Growth Stages ◽  
Annual Ryegrass ◽  
Application Time ◽  
Lolium Rigidum ◽  
Single Application ◽  
Herbicide Application ◽  
Leaf Stage ◽  
The Difference

Applying glyphosate followed by a mixture of paraquat + diquat in the same season for pre-planting weed control may reduce the risk of developing resistance to either herbicide. Glasshouse and field experiments at Merredin and Beverly, Western Australia, were conducted over 2 seasons to determine the best herbicide application sequence, growth stage of annual ryegrass at which to apply the 2 herbicides, and application time and interval to be allowed between applications for optimum control of annual ryegrass (Lolium rigidum Gaud.). Annual ryegrass plants were treated at 3 growth stages with either glyphosate 540 g a.i./ha alone, paraquat + diquat 250 g a.i./ha alone, glyphosate followed by paraquat + diquat 250 g a.i./ha, or paraquat + diquat 250 g a.i./ha followed by glyphosate 540 g a.i./ha (the double knockdown treatment). The herbicides were applied at different times of the day, with varied intervals between herbicides when applied in sequence. The glasshouse experiment showed that herbicides in sequence more effectively killed annual ryegrass plants at the 3–6-leaf stage than a single application of either herbicide. Field experiments showed that applying glyphosate followed by paraquat + diquat provided 98–100% control of annual ryegrass plants when applied at the 3- or 6-leaf stage in 2002 and at all 3 growth stages in 2003. Generally, the sequence of paraquat + diquat followed by glyphosate was less effective than the reverse sequence, although the difference was not large. Averaged over 2 seasons, herbicides in sequence were most effective when the first herbicide was applied at the 3- or 6-leaf stage of annual ryegrass. An interval of 2–10 days between applications of herbicides was more effective than 1 day or less. The application time did not significantly affect the efficacy of double knockdown herbicides on annual ryegrass plants under field conditions.

Common Waterplantain,Alisma plantago-aquatica, Control in Wild Rice,Zizania palustris, with MCPA and 2,4-D

1988 ◽  
Vol 2 (3) ◽  
pp. 310-316 ◽  
Author(s):  
Joel K. Ransom ◽  
Ervin A. Oelke
Keyword(s):  
Wild Rice ◽  
Growth Stage ◽  
Field Experiments ◽  
Rice Yield ◽  
Leaf Growth ◽  
Application Time ◽  
Flowering Stage ◽  
Leaf Stage ◽  
Late Season ◽  
Treatment Stage

Field experiments were conducted to evaluate the effect of application time on common waterplantain control in wild rice with MCPA and 2,4-D. Common waterplantain control was greatest when MCPA or 2,4-D were applied at 1.1 or 1.7 kg ai/ha at the two-aerial leaf stage. The best late-season control was MCPA applied at the scape elongation growth stage. Common waterplantain was controlled adequately when 0.6 to 0.8 kg/ha of MCPA were applied at the scape elongation or early flowering stage. However, because of common water plantain interference and sensitivity of wild rice to late herbicide applications, the best treatment stage for wild rice yield was when MCPA was applied at 0.6 kg/ha to common waterplantain at the two-aerial leaf stage. Wild rice at this time is at the more tolerant one-aerial leaf growth stage.

scholarly journals Hormesis with glyphosate depends on coffee growth stage

2013 ◽  
Vol 85 (2) ◽  
pp. 813-822 ◽  
Author(s):  
LEONARDO B. DE CARVALHO ◽  
PEDRO L.C.A. ALVES ◽  
STEPHEN O. DUKE
Keyword(s):  
Plant Growth ◽  
Weed Management ◽  
Growth Stage ◽  
Growth Stages ◽  
Coffee Plant ◽  
Herbicide Application ◽  
Coffee Plantations ◽  
Plant Growth Stages ◽  
Coffee Plants ◽  
Almost All

Weed management systems in almost all Brazilian coffee plantations allow herbicide spray to drift on crop plants. In order to evaluate if there is any effect of the most commonly used herbicide in coffee production, glyphosate, on coffee plants, a range of glyphosate doses were applied directly on coffee plants at two distinct plant growth stages. Although growth of both young and old plants was reduced at higher glyphosate doses, low doses caused no effects on growth characteristics of young plants and stimulated growth of older plants. Therefore, hormesis with glyphosate is dependent on coffee plant growth stage at the time of herbicide application.

scholarly journals Comparative effects of grazing, herbicide or forage conservation on barley grass content in Trifolium subterraneum L. clover-based pasture

2019 ◽  
Vol 70 (9) ◽  
pp. 800
Author(s):  
John W. Piltz ◽  
Simon J. Flinn ◽  
Leslie A. Weston
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Annual Ryegrass ◽  
Lolium Rigidum ◽  
Herbicide Application ◽  
High Quality ◽  
Harvest Timing

Barley grass (Hordeum spp.) is a relatively short lived annual that provides high quality grazing early in the season, but its seed heads cause contamination of wool and carcasses, and may irritate the mouth, eyes and nose of sheep. Treatments were imposed on established subterranean clover (Trifolium subterraneum L.) annual pasture in the same plots for three consecutive years (2015 to 2017) to evaluate changes in barley grass content. Treatments included: grazing alone (G), herbicide followed by grazing (HG), or a forage conservation harvest in early October, late October or early November consistent with an early silage harvest (ES), late silage harvest (LS) or hay cut (H). Grazing plus herbicide markedly reduced (P < 0.05) barley grass numbers compared with all other treatments, but increased (P < 0.05) the growth of annual ryegrass (Lolium rigidum L.). ES reduced (P < 0.05) barley grass and increased (P < 0.05) subterranean clover compared with H, but broadleaf weed content benefitted by LS in contrast to either ES or H. Although herbicide application was the most effective method for barley grass control, forage harvest timing could be used to beneficially manipulate pasture composition.

The critical weed-free period in glyphosate-resistant soybean in Ontario is similar to previous estimates using glyphosate-susceptible soybean

2019 ◽  
Vol 99 (4) ◽  
pp. 437-443
Author(s):  
Nader Soltani ◽  
Robert E. Nurse ◽  
Amit J. Jhala ◽  
Peter H. Sikkema
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Yield Loss ◽  
Growth Stages ◽  
Weed Species ◽  
Weed Biomass ◽  
Weed Density ◽  
Weed Interference ◽  
Beginning Of Flowering ◽  
Minimal Reduction

A study consisting of 13 field experiments was conducted during 2014–2016 in southwestern Ontario and southcentral Nebraska (Clay Center) to determine the effect of late-emerging weeds on the yield of glyphosate-resistant soybean. Soybean was maintained weed-free with glyphosate (900 g ae ha−1) up to the VC (cotyledon), V1 (first trifoliate), V2 (second trifoliate), V3 (third trifoliate), V4 (fourth trifoliate), and R1 (beginning of flowering) growth stages, after which weeds were allowed to naturally infest the soybean plots. The total weed density was reduced to 24%, 63%, 67%, 72%, 76%, and 92% in Environment 1 (Exeter, Harrow, and Ridgetown) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 soybean growth stages, respectively. The total weed biomass was reduced by 33%, 82%, 95%, 97%, 97%, and 100% in Environment 1 (Exeter, Harrow, and Ridgetown) and 28%, 100%, 100%, 100%, 100%, and 100% in Environment 2 (Clay Center) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 stages, respectively. The critical weed-free periods for a 2.5%, 5%, and 10% yield loss in soybean were the V1–V2, VC–V1, and VC–V1 soybean stages in Environment 1 (Exeter, Harrow, and Ridgetown) and V2–V3, V2–V3, and V1–V2 soybean stages in Environment 2 (Clay Center), respectively. For the weed species evaluated, there was a minimal reduction in weed biomass (5% or less) when soybean was maintained weed-free beyond the V3 soybean growth stage. These results shows that soybean must be maintained weed-free up to the V3 growth stage to minimize yield loss due to weed interference.

The effect of cotton growth stage on response to a sublethal concentration of 2,4-D

2019 ◽  
Vol 33 (2) ◽  
pp. 321-328 ◽  
Author(s):  
John T. Buol ◽  
Daniel B. Reynolds ◽  
Darrin M. Dodds ◽  
J. Anthony Mills ◽  
Robert L. Nichols ◽  
...  
Keyword(s):  
Fiber Length ◽  
Growth Stage ◽  
Field Experiments ◽  
Fruit Set ◽  
Sublethal Concentration ◽  
Growth Stages ◽  
Visible Injury ◽  
Fiber Properties ◽  
Low Concentrations ◽  
Auxin Herbicides

AbstractRecent commercialization of auxin herbicide–based weed control systems has led to increased off-target exposure of susceptible cotton cultivars to auxin herbicides. Off-target deposition of dilute concentrations of auxin herbicides can occur on cotton at any stage of growth. Field experiments were conducted at two locations in Mississippi from 2014 to 2016 to assess the response of cotton at various growth stages after exposure to a sublethal 2,4-D concentration of 8.3 g ae ha−1. Herbicide applications occurred weekly from 0 to 14 weeks after emergence (WAE). Cotton exposure to 2,4-D at 2 to 9 WAE resulted in up to 64% visible injury, whereas 2,4-D exposure 5 to 6 WAE resulted in machine-harvested yield reductions of 18% to 21%. Cotton maturity was delayed after exposure 2 to 10 WAE, and height was increased from exposure 6 to 9 WAE due to decreased fruit set after exposure. Total hand-harvested yield was reduced from 2,4-D exposure 3, 5 to 8, and 13 WAE. Growth stage at time of exposure influenced the distribution of yield by node and position. Yield on lower and inner fruiting sites generally decreased from exposure, and yield partitioned to vegetative or aborted positions and upper fruiting sites increased. Reductions in gin turnout, micronaire, fiber length, fiber-length uniformity, and fiber elongation were observed after exposure at certain growth stages, but the overall effects on fiber properties were small. These results indicate that cotton is most sensitive to low concentrations of 2,4-D during late vegetative and squaring growth stages.

Winter Wheat (Triticum aestivum) Growth Stage Effect on Paraquat Bioactivity

1991 ◽  
Vol 5 (2) ◽  
pp. 439-441
Author(s):  
Randy L. Anderson ◽  
David C. Nielsen
Keyword(s):  
Triticum Aestivum ◽  
Winter Wheat ◽  
Growth Stage ◽  
Time Of Day ◽  
Growth Stages ◽  
Leaf Stage ◽  
Time Of Application ◽  
Biomass Reduction

Paraquat was applied at 0.28 and 0.56 kg ai ha-1to winter wheat at five growth stages at 0800, 1300, and 1600 hr to determine whether growth stage or time of application influenced winter wheat response to paraquat. Paraquat bioactivity was affected by growth stage. Biomass reduction by paraquat was 84% when winter wheat was in the 1 to 3 leaf stage, but only 68% when application was delayed until tillering. Paraquat bioactivity continued to decrease at later growth stages. The time of day when paraquat was applied did not affect its bioactivity on winter wheat.

scholarly journals Rhizopus Head Rot of Confectionery Sunflower: Effects on Yield Quantity and Quality and Implications for Disease Management

1997 ◽  
Vol 87 (12) ◽  
pp. 1226-1232 ◽  
Author(s):  
D. Shtienberg
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Rhizopus Oryzae ◽  
Development Stage ◽  
Crop Growth ◽  
Growth Stages ◽  
Yield Quality ◽  
Crop Growth Stage ◽  
Head Rot ◽  
The Individual

The effects of Rhizopus head rot, caused by Rhizopus oryzae, on the yield of confectionery sunflower and its quality were studied in field experiments conducted from 1994 to 1996. The extent of yield loss was related to the crop growth stage at inoculation. When heads were inoculated at the budding stage, loss was not apparent, because inoculated heads were not infected. When inoculated at the anthesis stage, loss was relatively high (42.5 to 99.1%), and both the number of achenes per head and the individual achene weight were reduced. When heads were inoculated at the seed development stage, yield was not reduced significantly (although the entire receptacle was rotted). Effects of Rhizopus head rot on measures of yield quality were examined as well. Inoculation with R. oryzae did not affect the size of the achenes at any crop growth stage. In contrast, the incidence of discolored achenes (an external sign of nutmeats with a bitter off-flavor) was affected by the disease at all crop growth stages. A survey in eight commercial fields from 1992 to 1996 found that, by the end of the season, incidence of disease ranged from 2.3 to 17.4%. However, since disease intensified late, resultant yield losses were minor and did not exceed 3.1%. Loss figures were estimated by means of a model that was developed and validated in the field experiments. The disease did affect the incidence of discolored achenes. Thus, the conclusion drawn is that the effects of Rhizopus head rot in confectionery sunflower on crop yield is of minimal concern, at least when disease intensifies late, as was the case in the studied fields, but management of the disease should be considered in some situations. The objectives would be to prevent a reduction in yield quality, not yield quantity.

Effects of Herbicide Application Timing on Johnsongrass (Sorghum halepense) and Pitted Morningglory (Ipomoea lacunosa) Control

1990 ◽  
Vol 4 (4) ◽  
pp. 900-903 ◽  
Author(s):  
David R. Shaw ◽  
Sunil Ratnayake ◽  
Clyde A. Smith
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Sorghum Halepense ◽  
Herbicide Application ◽  
Ipomoea Lacunosa ◽  
Application Timing ◽  
Final Treatment ◽  
Pitted Morningglory

Field experiments were conducted to evaluate the influence of application timing of imazethapyr and fluazifop-P on rhizome johnsongrass and pitted morningglory control in soybean. Herbicides were applied at three timings keyed to johnsongrass heights of 15, 30, and 60 cm and 3-, 6-, and 9-leaf pitted morningglory. Evaluations 6 wk after the final treatment indicated imazethapyr controlled both species best when applied at the 15-cm johnsongrass growth stage. Increasing imazethapyr rate did not increase control of pitted morningglory, but did increase johnsongrass control at the 15-cm application timing. However, at the 30-cm johnsongrass application timing, increasing the rate from 0.07 to 0.10 kg ha-1improved control of both species. Johnsongrass control with imazethapyr was no more than 64% when applications were delayed to 30-cm or larger johnsongrass. Fluazifop-P controlled johnsongrass well at all timings.

Postemergence control of quackgrass [Elytrigia repens (L) Nevski] with DPX-79406 in corn (Zea mays L)

1994 ◽  
Vol 74 (2) ◽  
pp. 375-381 ◽  
Author(s):  
M. E. Reidy ◽  
C. J. Swanton
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Significant Interaction ◽  
Growth Stage ◽  
Field Experiments ◽  
Zea Mays L ◽  
Optimum Dose ◽  
Corn Yield ◽  
Leaf Stage ◽  
Elytrigia Repens

Laboratory and field experiments were established to determine the optimum dose and timing of postemergence applications of DPX-79406 for quackgrass control. Four node quackgrass rhizome fragments from each biotype were grown under controlled conditions. At the three-to-four-leaf stage, quackgrass plants were sprayed with DPX-79406 and evaluated for control. A significant response of quackgrass biotypes to DPX-79406 was evident only at lower doses. In the field, quackgrass was effectively controlled by all doses of DPX-79406. Significant growth-stage effects were observed for quackgrass shoot and rhizome dry weights in the year of application and in the year following application. There was a significant interaction between year and growth stage. In 1990, quackgrass biomass was greater when DPX-79406 was applied at the two-to-three-leaf stage of quackgrass than at the four-to-five-leaf stage. In 1991, however, the opposite occurred. Within a growth stage, the 6.25 g ha−1 dose was as effective for controlling quackgrass as 18.5 g ha−1, in both years of the study. In 1991, significant decreases in corn yield were observed for DPX-79406 doses of > 12.5 g ha−1 applied at the four-to-five-leaf stage of quackgrass. For all the variables studied, DPX-79406 doses of 6.25–12.5 g ha−1 resulted in consistent control of quackgrass. Key words: DPX-79406, nicosulfuron, rimsulfuron, quackgrass, Elytrigia repens, corn, Zea mays

A review of copper fertilizer management for optimum yield and quality of crops in the Canadian Prairie provinces

2006 ◽  
Vol 86 (3) ◽  
pp. 605-619 ◽  
Author(s):  
S. S. Malhi ◽  
R. E. Karamanos
Keyword(s):  
Seed Yield ◽  
Growth Stage ◽  
Field Experiments ◽  
Seed Quality ◽  
Soil Analysis ◽  
Growth Stages ◽  
Canadian Prairie ◽  
Cu Deficiency ◽  
Yield And Quality

Deficiency of copper (Cu) in Canadian prairie soils is not widespread, but whenever it occurs it can cause a drastic reduction in seed yield and quality of most cereals, especially wheat. Field experiments conducted in western Canada indicated that broadcast-incorporation of granular Cu fertilizers prior to seeding at 3-5.6 kg Cu ha-1 was usually sufficient to prevent Cu deficiency in wheat, and improve seed yield and quality. At lower rates (< 2.0 kg Cu ha-1), broadcast-incorporation of granular Cu fertilizers was not effective, while surface spray-broadcast followed by incorporation of liquid Cu fertilizers was much more effective in increasing seed yield of wheat in the first year of application. Surface broadcast without incorporation and seedrow-placed granular Cu fertilizers were much less effective in improving seed yield of wheat than their foliar or soil-incorporated applications. In the growing season, foliar applications of Cu at 0.20 to 0.28 kg Cu ha-1 to wheat at the Feekes 6 (first node of stem visible at base of shoot or stem elongation), Feekes 10 (sheath of last leaf completely grown or flag-leaf) and early boot growth stages were very effective in restoring seed yield, while Cu applications at the Feekes 2 (four-leaf) or Feekes 10.5 (complete heading) growth stage did not have a consistent effect to correct damage caused by Cu deficiency. Some Cu fertilizers (e.g., Cu oxide) were less effective than others in preventing/correcting Cu deficiency. Soil application at relatively high rates produced residual benefits in increasing seed yield for a number of years. The sensitivity of crops to Cu deficiency is usually in the order (wheat, flax, canary seed) > (barley, alfalfa) > (timothy seed, oats, corn) > (peas, clovers) > (canola, rye, forage grasses). Stem melanosis in wheat was associated with deficiency of Cu in soil, and the disease was reduced substantially with Cu application. A high level of available P in soil was observed to induce/increase severity of Cu deficiency in wheat. Soil analysis for diethylene triamine pentacetic acid- (DTPA) extractable Cu in soil can be used as a good diagnostic tool to predict Cu deficiency, but there was a poor relationship between total Cu concentration in shoots and the degree of Cu deficiency in crops. Application of Cu fertilizers to wheat on Cu-deficient soils also generally improved seed quality. Key words: Application time, Cu source, foliar application, granular Cu, growth stage, placement method, rate of Cu, seedrow-placed Cu, soil incorporation, wheat

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