scholarly journals Glyphosate Tolerance of Two Perennial Ryegrass Cultivars from Fall Applications and at Seedling Growth Stages

HortScience ◽  
2015 ◽  
Vol 50 (2) ◽  
pp. 304-309
Author(s):  
Christian M. Baldwin ◽  
Eugene K. Blythe ◽  
A. Douglas Brede ◽  
Jami J. Mayer ◽  
R. Golembiewski
Keyword(s):  
Perennial Ryegrass ◽  
Temperature Response ◽  
Field Trials ◽  
Application Rate ◽  
Growth Stages ◽  
Annual Bluegrass ◽  
Air Temperatures ◽  
The One ◽  
Fall Application ◽  
Response Trial

The use of glyphosate-tolerant perennial ryegrass (Lolium perenne L.) (PRG) cultivars JS501 and Replay provides turfgrass managers a unique option for annual bluegrass (Poa annua L.) (ABG) control. Both cultivars can tolerate a maximum glyphosate rate of 0.81 kg·ha−1 acid equivalent (a.e.) after establishment under optimal growing temperatures (16 to 24 °C). However, tolerance to applications made immediately after germination and during low air temperatures has received limited investigation. Therefore, objectives of this research were to determine the seedling tolerance and low-temperature response after a fall season glyphosate application to both cultivars. Field trials were conducted in Idaho and Oregon. For the fall application response trial in Idaho, glyphosate was applied at 0, 0.15, 0.29, 0.58, 1.16, 1.74, 2.32, and 3.48 kg·ha−1 a.e. In Oregon, glyphosate was applied at 0, 0.15, 0.29, 0.44, 0.58, 1.16, and 3.48 kg·ha−1 a.e. At both sites, applications were made between late September and early October. To determine seedling tolerance, both cultivars were sprayed with glyphosate at the one-leaf stage (LS), two LS, three LS, or four LS at rates of 0, 0.15, 0.29, and 0.58 kg·ha−1 a.e. Across all trials, ratings included PRG color, cover, and injury. At both trial locations, regression analysis revealed a rate of ≈0.27 kg·ha−1 a.e. was required to cause 20% leaf firing in the fall application response trial. In the seedling tolerance trial, glyphosate applied at 0.58 kg·ha−1 a.e. at the one LS, two LS, and three LS had color ratings 8.0 or greater; however, color ratings dropped to 4.6 when an application was made at the four LS. Based on the environmental conditions of each trial, results suggest glyphosate applications greater than 0.27 kg·ha−1 a.e. as minimum air temperatures approach 0 °C should be avoided. Also, applications should be avoided at the three to four LS if the application rate is greater than 0.29 kg·ha−1 a.e.

scholarly journals ‘JS501’ and ‘Replay’ Perennial Ryegrass Glyphosate Tolerance and Rates Required for Annual Bluegrass (Poa annua L.) Control

HortScience ◽  
2012 ◽  
Vol 47 (7) ◽  
pp. 932-935 ◽  
Author(s):  
Christian M. Baldwin ◽  
A. Douglas Brede ◽  
Jami J. Mayer
Keyword(s):  
Perennial Ryegrass ◽  
Weed Management ◽  
Linear Regression Analysis ◽  
Cost Savings ◽  
Field Trials ◽  
Application Rate ◽  
Management Program ◽  
Poa Annua ◽  
Glyphosate Tolerance ◽  
Annual Bluegrass

Incorporating the use of glyphosate into a weed management program offers turfgrass managers increased flexibility and cost savings when attempting to control troublesome weeds such as annual bluegrass (ABG) (Poa annua L.). Field trials of glyphosate tolerant perennial ryegrass (PRG) (Lolium perenne L.) cultivars, JS501 and Replay, were initiated to determine glyphosate tolerance and rates required for ABG control. In the tolerance trial, glyphosate was applied on 15 Sept. 2010 and 9 Aug. 2011 at rates of 0, 0.29, 0.58, 1.16, 1.74, 2.32, and 3.48 kg·ha−1 a.e. Glufosinate was also applied at 0, 1.68, and 3.37 kg·ha−1 a.i. In the ABG control trial, glyphosate was applied on 17 June followed by 19 Aug. 2009 and 25 June followed by 25 Aug. 2010 at rates of 0, 0.15, 0.29, 0.44, and 0.58 kg·ha−1 a.e. In the tolerance trial, linear regression analysis revealed a glyphosate application rate of 0.81 kg·ha−1 a.e. was required to cause 20% leaf firing. By the end of the trial, the highest rate of glufosinate resulted in nearly complete desiccation of ‘Replay’ PRG. For ABG control, after four glyphosate applications over a 2-year period, a rate of 0.29 kg·ha−1 a.e. or greater resulted in less than 10% ABG. Untreated plots had ≈83% ABG infestation. Discoloration was not noted for either PRG cultivar at any point over the 2-year trial period. Based on the environmental conditions of each trial, results suggest a recommended application rate should be 0.29 kg·ha−1 a.e. during summer months. This rate is sufficient for ABG control and also provides protection in case spray overlap occurs during an application.

Rate response of select grass weeds to pinoxaden

2020 ◽  
Vol 34 (6) ◽  
pp. 818-823 ◽  
Author(s):  
John M. Peppers ◽  
Clebson G. Gonçalves ◽  
J. Scott McElroy
Keyword(s):  
Perennial Ryegrass ◽  
Application Rate ◽  
Fresh Weight ◽  
Weed Species ◽  
Visible Injury ◽  
Injury Rates ◽  
Annual Bluegrass ◽  
Spray Rate ◽  
Acetyl Coenzyme A Carboxylase ◽  
Large Crabgrass

AbstractPinoxaden is a POST acetyl coenzyme A carboxylase (ACCase) inhibitor in the phenylpyrazolin chemical family and is labelled for turfgrass use at broadcast rates of 35.5 to 71 g ai ha−1 and spot spray rates of 156 to 310 g ai ha−1. A greenhouse rate-response study was conducted to characterize the efficacy of pinoxaden against common grassy weeds. Weed species examined in this study were yellow foxtail, southern sandbur, annual bluegrass, roughstalk bluegrass, large crabgrass, dallisgrass, bahiagrass, goosegrass, and perennial ryegrass. Nonlinear regressions were modelled to determine visible injury rates (the application rate at which 50% of the weed species were injured and the 90% [I90] rate) and weight reduction rates (the application rate at which there was a 50% reduction in fresh weight and 90% reduction [WR90]) for each weed species. Only annual bluegrass, bahiagrass, and goosegrass had visible injury I90 values greater than the maximum labelled spot spray rate of 310 g ai ha−1. Annual bluegrass, bahiagrass, southern sandbur, and goosegrass all had WR90 values greater than the maximum labelled spot spray rate of 310 g ai ha−1. Results from this study indicate that the evaluated weed species can be ranked, according to visible injury I90 values, from most to least susceptible: perennial ryegrass > yellow foxtail > dallisgrass > large crabgrass > southern sandbur > roughstalk bluegrass > bahiagrass > goosegrass > annual bluegrass.

scholarly journals Postemergence Control of Annual Bluegrass with Mesotrione in Kentucky Bluegrass

HortScience ◽  
2012 ◽  
Vol 47 (4) ◽  
pp. 522-526 ◽  
Author(s):  
Joshua J. Skelton ◽  
William Sharp ◽  
Bruce E. Branham
Keyword(s):  
Environmental Conditions ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Field Trials ◽  
Poa Annua ◽  
Annual Bluegrass ◽  
Air Temperatures ◽  
Significant Application ◽  
Levels Of Control

Six field trials were conducted in 2009 and 2010 to study postemergence control of annual bluegrass (Poa annua L. var. Hausskn Timm) in kentucky bluegrass (Poa pratensis L.) with mesotrione. Mesotrione was applied at 11 different rate and application intervals to an area of kentucky bluegrass that was naturally infested with annual bluegrass. Mesotrione rates of 56 g·ha−1 applied two or three times per week for a total of 10 applications or 84 g·ha−1 applied two times per week for a total of seven applications provided consistent control of annual bluegrass but required significant application labor and resulted in minor kentucky bluegrass injury. Other treatments that required fewer applications, 110 g·ha−1 applied twice per week for five applications or 186 g·ha−1 per week for three applications, also achieved high levels of control under high air temperatures, but control levels can vary significantly as temperatures fluctuate and seasons change. Mesotrione can successfully control annual bluegrass in kentucky bluegrass when frequent applications at low rates are applied or when environmental conditions are conducive to control.

Soybean Sensitivity to Drift Rates of Imazosulfuron

2014 ◽  
Vol 28 (3) ◽  
pp. 443-453 ◽  
Author(s):  
Sandeep S. Rana ◽  
Jason K. Norsworthy ◽  
Robert C. Scott
Keyword(s):  
Growth Stage ◽  
Yield Loss ◽  
Field Trials ◽  
Application Rate ◽  
Early Growth ◽  
Growth Stages ◽  
Sulfonylurea Herbicide ◽  
Full Bloom ◽  
Close Proximity ◽  
Different Growth Stages

Imazosulfuron is a sulfonylurea herbicide recently labeled in U.S. rice at a maximum rate of 336 g ai ha−1. Soybean is prone to drift of herbicides from rice fields in the southern United States because these crops are often grown in close proximity. Field trials were conducted to determine the effect of low rates of imazosulfuron applied to nonsulfonylurea-resistant soybean at different growth stages. Soybean was treated at the vegetative cotyledonary (VC); vegetative second trifoliate (V2); vegetative sixth trifoliate (V6); and reproductive full bloom (R2) growth stages with 1/256 (1.3 g ha−1) to 1/4 (84.1 g ha−1) times (X) the maximum labeled rate of imazosulfuron. Soybean was injured regardless of application rate or timing. At 2 wk after treatment (WAT), imazosulfuron injured soybean 23 to 79, 44 to 76, 32 to 68, and 14 to 50% when applied at the VC, V2, V6, and R2 growth stages, respectively, where the highest injury was caused by the highest imazosulfuron rate (1/4X). However, by 20 wk after planting (WAP), soybean treated with imazosulfuron at the VC and V2 growth stages had only 0 to 17% and 8 to 53% injury, respectively. At higher rates [1/8 (42 g ha−1) and 1/4X] of imazosulfuron, soybean treated at the VC growth stage recovered more from injury than did soybean treated at the V2 growth stage. Soybean treated with imazosulfuron at the V6 and R2 growth stages had better recovery from the injury at the lower two rates [1/256 and 1/128X (2.6 g ha−1)] than at the higher rates [1/64 (5.3 g ha−1) to 1/4X]. Imazosulfuron, at all rates tested, delayed soybean maturity by 1 to 4, 2 to 6, 1 to 12, and 3 to 16 d for the VC, V2, V6, and R2 growth stages, respectively. Yield loss was greater when imazosulfuron was applied at V6 and R2 compared to applications at VC and V2. Results from this research indicate that imazosulfuron can severely injure soybean regardless of the growth stage at which drift occurs; however, soybean injured by imazosulfuron at early growth stages (VC and V2) has a better chance of recovery over time compared to drift at later growth stages (V6 and R2).

Resistance of Enlist™ (AAD-12) Cotton to Glufosinate

2017 ◽  
Vol 31 (3) ◽  
pp. 380-386 ◽  
Author(s):  
L. Bo Braxton ◽  
John S. Richburg ◽  
Alan C. York ◽  
A. Stanley Culpepper ◽  
Robert A. Haygood ◽  
...  
Keyword(s):  
Growth Stage ◽  
Field Trials ◽  
Application Rate ◽  
Growth Stages ◽  
Cotton Yield ◽  
Single Application

Enlist™ cotton contains the aad-12 and pat genes that confer resistance to 2,4-D and glufosinate, respectively. Thirty-three field trials were conducted focused on Enlist cotton injury from glufosinate as affected by cotton growth stage, application rate, and single or sequential applications. Maximum injury from a single application of typical 1X (542 g ae ha-1) and 2X use rates was 3 and 13%, respectively, regardless of growth stage. Injury from sequential applications of 1X or 2X rates was equivalent to single applications. Similar injury was observed with four commercial formulations of glufosinate. Cotton yield was never affected by glufosinate. This research demonstrates Enlist™ cotton has robust resistance to glufosinate at rates at least twice the typical use rate when applied once or twice at growth stages ranging from 2 to 12 leaves.

Annual Bluegrass (Poa annua) Control in Glyphosate-Resistant Perennial Ryegrass Overseeding

2014 ◽  
Vol 28 (1) ◽  
pp. 213-224 ◽  
Author(s):  
Michael L. Flessner ◽  
J. Scott McElroy ◽  
Glenn R. Wehtje
Keyword(s):  
Weed Control ◽  
Perennial Ryegrass ◽  
Field Experiments ◽  
Application Rate ◽  
Poa Annua ◽  
Response Analysis ◽  
Single Application ◽  
Data Types ◽  
Annual Bluegrass ◽  
Greenhouse Experiments

‘Replay' and ‘JS501’ perennial ryegrass cultivars have been conventionally bred for reduced sensitivity to glyphosate, potentially allowing the herbicide to be used for selective weed control in overseeded bermudagrass. Field experiments were conducted to evaluate optimal glyphosate application rate, regime (single and sequential applications), and timing for annual bluegrass control in bermudagrass overseeded with these cultivars. Additionally, greenhouse experiments were conducted to compare the sensitivity to glyphosate of Replay and JS501 to susceptible cultivars ‘Caddy Shack' and ‘Top Gun II' through log-logistic rate-response analysis. In field experiments, only two treatments resulted in > 90% annual bluegrass control and < 25% perennial ryegrass injury. These two treatments were a single application of 280 g ae ha−1glyphosate in January and 140 g ha−1followed by an additional 140 g ha−1applied in January. Perennial ryegrass cultivars were compared using 50% inhibition (I50) values, i.e. 50% visible estimates of injury or 50% reduction in clipping weight.I50values obtained 6 wk after treatment from injury data were 2.56, 2.64, 0.81, and 0.84 g ha−1glyphosate for Replay, JS501, Caddy Shack, and Top Gun II, respectively. Replay and JS501 were similar in sensitivity to glyphosate and were up to four times more tolerant than Caddy Shack and Top Gun II across rating dates and data types.

scholarly journals Effects of nitrogen on development and growth of the leaves of vegetables. 2. Appearance, expansion growth and life span of leaves of leek plants

1995 ◽  
Vol 43 (2) ◽  
pp. 233-246 ◽  
Author(s):  
H. Biemond
Keyword(s):  
Leaf Area ◽  
Field Trials ◽  
Application Rate ◽  
Leaf Expansion ◽  
Mature Leaf ◽  
Growth Stages ◽  
Leaf Emergence ◽  
N Application Rate ◽  
Number Of Leaves ◽  
Leaf Appearance

In greenhouse pot experiments and field trials, leek cv. Albana plants were supplied with different amounts of N fertilizer at various growth stages. Leaf emergence, expansion, size and senescence were monitored. The rate of leaf appearance was not affected by N treatments and almost constant across experiments at 0.15/day. The rate of leaf expansion and the mature leaf area increased with leaf number, reaching maximum values between leaf numbers 11 and 14 and decreasing with higher leaf numbers. Both variables increased with increasing N application rate. The duration of leaf expansion was more or less constant across leaf numbers and not influenced by N treatments; the leaf expansion rate was the main factor determining mature leaf area. The rate of leaf senescence was not influenced by N treatments. Differences in total green leaf area per plant were caused by differences in the area of individual mature leaves and not by differences in the number of leaves. The specific leaf area of all leaves was more or less constant at 100 cmsuperscript 2/g.

scholarly journals Reproduction and biomarker responses of Eisenia fetida after exposure to imidacloprid in biochar-amended soil

Biochar ◽  
2021 ◽  
Author(s):  
Ngitheni Winnie-Kate Nyoka ◽  
Ozekeke Ogbeide ◽  
Patricks Voua Otomo
Keyword(s):  
Eisenia Fetida ◽  
Field Studies ◽  
Application Rate ◽  
Land Application ◽  
Acetylcholinesterase Inhibition ◽  
Beneficial Effects ◽  
Pesticide Pollution ◽  
The One ◽  
The Impact ◽  
Amended Soil

AbstractTerrestrial and aquatic ecosystems are increasingly threatened by pesticide pollution resulting from extensive use of pesticides, and due to the lack of regulatory measures in the developing world, there is a need for affordable means to lessen environmental effects. This study aimed to investigate the impact of biochar amendment on the toxicity of imidacloprid to life-cycle parameters and biomarker responses of the earthworm Eisenia fetida. E. fetida was exposed to 10% biochar-amended and non-amended OECD artificial soils spiked with 0, 0.75, 1.5, 2.25 and 3 mg imidacloprid/kg for 28 days. An LC50 of 2.7 mg/kg was only computed in the non-amended soil but not in the biochar-amended soil due to insignificant mortality. The EC50 calculated in the non-amended soil (0.92 mg/kg) for reproduction (fertility) was lower than the one computed in the biochar amended (0.98 mg/kg), indicating a decrease in toxicity in the biochar-amended substrate. Significant weight loss was observed at the two highest imidacloprid treatments in the non-amended soil and only at the highest treatment in the biochar-amended substrate, further highlighting the beneficial effects of biochar. Catalase activity decreased significantly at the two highest concentrations of non-amended soil. Yet, in the amended soil, the activity remained high, especially in the highest concentration, where it was significantly higher than the controls. This indicated more severe oxidative stress in the absence of biochar. In all non-amended treatments, there was a significant acetylcholinesterase inhibition, while lower inhibition percentages were observed in the biochar-amended soil. In most endpoints, the addition of biochar alleviated the toxic effects of imidacloprid, which shows that biochar has the potential to be useful in soil remediation. However, there is still a need for field studies to identify the most effective application rate of biochar for land application.

Evaluation of Harvest-Aid Herbicides as Desiccants in Lentil Production

2016 ◽  
Vol 30 (3) ◽  
pp. 629-638 ◽  
Author(s):  
Ti Zhang ◽  
Eric N. Johnson ◽  
Christian J. Willenborg
Keyword(s):  
Adverse Effects ◽  
Crop Yield ◽  
Seed Yield ◽  
Yield Loss ◽  
Field Trials ◽  
Growth Stages ◽  
Yield And Quality ◽  
Seed Field ◽  
Dry Down ◽  
General Reduction

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.

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