scholarly journals Herbicide performance in the control of Conyza spp. where three plant heights

2021 ◽  
Vol 37 ◽  
pp. e37091
Author(s):  
Theodoro Schneider ◽  
Juliane Nicolodi Camera ◽  
Jana Koefender ◽  
Mauro Antônio Rizzardi ◽  
Mario Antônio Bianchi ◽  
...  
Keyword(s):  
Developmental Stage ◽  
Field Experiments ◽  
Maximum Height ◽  
Herbicide Resistant ◽  
Ammonium Glufosinate ◽  
Intensive Use ◽  
And Control ◽  
Herbicide Glyphosate

Intensive use of the herbicide glyphosate has led to herbicide resistant Conyza spp. populations. Thus, there is a need to indicate alternative herbicides and the appropriate developmental stage for controlling these populations. This study identifies alternatives for controlling glyphosate-resistant horseweed, with treatment applications at different plant heights. For this purpose, field experiments were conducted in the 2016/17 and 2017/18 crop years. The evaluated treatments were: glyphosate (540 g ae ha-1), glyphosate (1080 g ae ha-1), glyphosate (2160 g ae ha-1), glyphosate (3240 g ae ha-1), glyphosate + 2.4-D (1080 + 1005 g ae ha-1), glyphosate + saflufenacil (1080 + 49 g ae/ai ha-1), paraquat (400 g ai ha-1), diquat (400 g ai ha-1), ammonium glufosinate (600 g ai ha-1), and control (without application). These treatments were applied to plants with a maximum of 5 cm; plants between 6 and 15 cm; and plants between 16 and 25 cm. The results showed that glyphosate did not control weeds, regardless of rate. With the exception of 2,4-D, which needs complementation with sequential application of another contact herbicide, all alternatives were viable for the control of Conyza spp. plants with a maximum height of 5 cm.

Characterization of multiple herbicide–resistant waterhemp (Amaranthus tuberculatus) populations from Illinois to VLCFA-inhibiting herbicides

Weed Science ◽  
2019 ◽  
Vol 67 (4) ◽  
pp. 369-379 ◽  
Author(s):  
Seth A. Strom ◽  
Lisa C. Gonzini ◽  
Charlie Mitsdarfer ◽  
Adam S. Davis ◽  
Dean E. Riechers ◽  
...  
Keyword(s):  
Dose Response ◽  
Field Experiments ◽  
Survival Rates ◽  
Acetolactate Synthase ◽  
Field Studies ◽  
Complete Control ◽  
Herbicide Resistant ◽  
Amaranthus Tuberculatus ◽  
Als Inhibitors ◽  
And Control

AbstractField experiments were conducted in 2016 and 2017 in Champaign County, IL, to study a waterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer] population (CHR) resistant to 2,4-D and 4-hydroxyphenylpyruvate dioxygenase (HPPD)-, photosystem II–, acetolactate synthase (ALS)-, and protoporphyrinogen oxidase–inhibiting herbicides. Two field experiments were designed to investigate the efficacy of very-long-chain fatty-acid (VLCFA)-inhibiting herbicides, including a comparison of active ingredients at labeled use rates and a rate titration experiment. Amaranthus tuberculatus density and control were evaluated at 28 and 42 d after treatment (DAT). Nonencapsulated acetochlor, alachlor, and pyroxasulfone provided the greatest PRE control of CHR (56% to 75%) at 28 DAT, while metolachlor, S-metolachlor, dimethenamid-P, and encapsulated acetochlor provided less than 27% control. In the rate titration study, nonencapsulated acetochlor controlled CHR more than equivalent field use rates of S-metolachlor. Subsequent dose–response experiments with acetochlor, S-metolachlor, dimethenamid-P, and pyroxasulfone in the greenhouse included three multiple herbicide–resistant (MHR) A. tuberculatus populations: CHR-M6 (progeny generated from CHR), MCR-NH40 (progeny generated from Mclean County, IL), and ACR (Adams County, IL), in comparison with a sensitive population (WUS). Both CHR-M6 and MCR-NH40 are MHR to atrazine and HPPD, and ALS inhibitors and demonstrated higher survival rates (LD50) to S-metolachlor, acetochlor, dimethenamid-P, or pyroxasulfone than ACR (atrazine resistant but HPPD-inhibitor sensitive) and WUS. Based on biomass reduction (GR50), resistant to sensitive (R:S) ratios between CHR-M6 and WUS were 7.5, 6.1, 5.5, and 2.9 for S-metolachlor, acetochlor, dimethenamid-P, and pyroxasulfone, respectively. Values were greater for MCR-NH40 than CHR-M6, and ACR was the most sensitive to all VLCFA inhibitors tested. Complete control of all populations was achieved at or below a field use rate of acetochlor. In summary, field studies demonstrated CHR is not controlled by several VLCFA-inhibiting herbicides. Greenhouse dose–response experiments corroborated field results and generated R:S ratios (LD50) ranging from 4.5 to 64 for CHR-M6 and MCR-NH40 among the four VLCFA-inhibiting herbicides evaluated.

The Effect of Trifluralin Applied Preplant on Grass Weed Control and Establishment and Yield of Barley (Hordeum vulgare)

1997 ◽  
Vol 11 (3) ◽  
pp. 515-519 ◽  
Author(s):  
Julio A. Scursoni ◽  
Emilio H. Satorre
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Herbicide Application ◽  
Planting Pattern ◽  
Weed Density ◽  
Time Of Application ◽  
Density And Biomass ◽  
And Control ◽  
Crop Planting ◽  
Grass Weed

The objective of this paper was to evaluate the effect of preplant applications of trifluralin on barley stand and yield, and control of grass weeds in field experiments during 1992 and 1993. Factors examined were: (1) crop planting patterns (conventional drill with rows 15 cm apart and deep-seeder drill with rows 25 cm apart), (2) herbicide application times (22 d before sowing and immediately before sowing), and (3) herbicide application. During 1993, hand-weeded plots also were established. Trifluralin applied preplant at 528 g ai/ha reduced weed density and biomass. Weed control was higher under conventional planting than under the deep planting pattern, and there was no effect of the time of application on herbicide efficacy. There was no herbicide injury to the crop, and grain yield was higher in treated than in untreated plots due to successful weed control.

scholarly journals Metalearners for estimating heterogeneous treatment effects using machine learning

2019 ◽  
Vol 116 (10) ◽  
pp. 4156-4165 ◽  
Author(s):  
Sören R. Künzel ◽  
Jasjeet S. Sekhon ◽  
Peter J. Bickel ◽  
Bin Yu
Keyword(s):  
Machine Learning ◽  
Treatment Effects ◽  
Field Experiments ◽  
Average Treatment Effect ◽  
Regularity Conditions ◽  
Heterogeneous Treatment Effects ◽  
Lipschitz Continuous ◽  
Additive Regression ◽  
Underlying Mechanisms ◽  
And Control

There is growing interest in estimating and analyzing heterogeneous treatment effects in experimental and observational studies. We describe a number of metaalgorithms that can take advantage of any supervised learning or regression method in machine learning and statistics to estimate the conditional average treatment effect (CATE) function. Metaalgorithms build on base algorithms—such as random forests (RFs), Bayesian additive regression trees (BARTs), or neural networks—to estimate the CATE, a function that the base algorithms are not designed to estimate directly. We introduce a metaalgorithm, the X-learner, that is provably efficient when the number of units in one treatment group is much larger than in the other and can exploit structural properties of the CATE function. For example, if the CATE function is linear and the response functions in treatment and control are Lipschitz-continuous, the X-learner can still achieve the parametric rate under regularity conditions. We then introduce versions of the X-learner that use RF and BART as base learners. In extensive simulation studies, the X-learner performs favorably, although none of the metalearners is uniformly the best. In two persuasion field experiments from political science, we demonstrate how our X-learner can be used to target treatment regimes and to shed light on underlying mechanisms. A software package is provided that implements our methods.

scholarly journals Confirmation and Control of HPPD-Inhibiting Herbicide–Resistant Waterhemp (Amaranthus tuberculatus) in Nebraska

2017 ◽  
Vol 31 (1) ◽  
pp. 67-79 ◽  
Author(s):  
Maxwel C. Oliveira ◽  
Amit J. Jhala ◽  
Todd Gaines ◽  
Suat Irmak ◽  
Keenan Amundsen ◽  
...  
Keyword(s):  
Dose Response ◽  
Field Conditions ◽  
Effective Control ◽  
Herbicide Resistant ◽  
Greenhouse Experiments ◽  
Amaranthus Tuberculatus ◽  
Sites Of Action ◽  
And Control ◽  
Herbicide Programs

Field and greenhouse experiments were conducted in Nebraska to (1) confirm the 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting resistant-waterhemp biotype (HPPD-RW) by quantifying the resistance levels in dose-response studies, and (2) to evaluate efficacy of PRE-only, POST-only, and PRE followed by POST herbicide programs for control of HPPD-RW in corn. Greenhouse dose-response studies confirmed that the suspected waterhemp biotype in Nebraska has evolved resistance to HPPD-inhibiting herbicides with a 2- to 18-fold resistance depending upon the type of HPPD-inhibiting herbicide being sprayed. Under field conditions, at 56 d after treatment, ≥90% control of the HPPD-RW was achieved with PRE-applied mesotrione/atrazine/S-metolachlor+acetochlor, pyroxasulfone (180 and 270 g ai ha−1), pyroxasulfone/fluthiacet-methyl/atrazine, and pyroxasulfone+saflufenacil+atrazine. Among POST-only herbicide programs, glyphosate, a premix of mesotrione/atrazine tank-mixed with diflufenzopyr/dicamba, or metribuzin, or glufosinate provided ≥92% HPPD-RW control. Herbicide combinations of different effective sites of action in mixtures provided ≥86% HPPD-RW control in PRE followed by POST herbicide programs. It is concluded that the suspected waterhemp biotype is resistant to HPPD-inhibiting herbicides and alternative herbicide programs are available for effective control in corn. The occurrence of HPPD-RW in Nebraska is significant because it limits the effectiveness of HPPD-inhibiting herbicides.

Efficacy of Halauxifen-Methyl on Glyphosate-Resistant Horseweed (Erigeron canadensis)

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 758-763 ◽  
Author(s):  
Cara L. McCauley ◽  
William G. Johnson ◽  
Bryan G. Young
Keyword(s):  
Zea Mays ◽  
Glycine Max ◽  
Field Experiments ◽  
Foliar Application ◽  
Management Systems ◽  
Herbicide Resistant ◽  
Synthetic Auxin ◽  
Comparable Level ◽  
Erigeron Canadensis ◽  
Application Rates

AbstractHalauxifen-methyl is a new synthetic auxin herbicide for control of broadleaf weeds, including preplant applications for corn (Zea maysL.) or soybean [Glycine max(L.) Merr.]. The objective of this study was to investigate the efficacy of halauxifen-methyl in comparison to the current auxin standards, 2,4-D and dicamba, on glyphosate-resistant (GR) horseweed (Erigeron canadensisL.) at different plant heights. In field experiments, a foliar application of halauxifen-methyl at the recommended use rate of 5 g ae ha−1resulted in 81% control. Dicamba applied at 280 g ae ha−1provided a comparable level of efficacy of 80%, while 2,4-D at 560 g ae ha−1resulted in 49% control. The addition of glyphosate improved GRE. canadensiscontrol with 2,4-D more than with halauxifen-methyl or dicamba, possibly due to the higher level of control observed with halauxifen-methyl or dicamba alone. Even though applied at 50 to 100 times lower application rates, the efficacy of halauxifen-methyl onE. canadensiswas similar to dicamba and greater than 2,4-D. Thus, halauxifen-methyl should be an effective tool for management of GRE. canadensisbefore planting both conventional and herbicide-resistant soybean varieties, and it precludes the extended preplant application interval required for dicamba in some soybean management systems.

Contamination of hay and haylage with enteric bacteria and selected antibiotic resistance genes following fertilization with dairy manure or biosolids.

2022 ◽  
Author(s):  
Andrew Scott ◽  
Roger Murray ◽  
Yuan-Ching Tien ◽  
Edward Topp
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Field Experiments ◽  
Antibiotic Resistance Genes ◽  
Enteric Bacteria ◽  
Dairy Manure ◽  
Plate Count ◽  
Growing Seasons ◽  
Route Of Exposure ◽  
And Control

The present study evaluated if enteric bacteria or antibiotic resistance genes carried in fecal amendments contaminate the hay at harvest, representing a potential route of exposure to ruminants that consume the hay. In field experiments, dairy manure was applied to a hay field for three successive growing seasons, and biosolids applied to a hay field for one growing season. Various enteric bacteria in the amendments were enumerated by viable plate count, and selected gene targets were quantified by qPCR. Key findings include the following: At harvest, hay receiving dairy manure or biosolids did not carry more viable enteric bacteria than did hay from unamended control plots. Fermentation of hay did not result in a detectable increase in viable enteric bacteria. The application of dairy manure or biosolids did result in a few gene targets being more abundant on hay at the first harvest. Fermentation of hay did result in an increase in the abundance of gene targets, but this occurred both with hay from amended and control plots. Overall, application of fecal amendments will result in an increase in the abundance of some gene targets associated with antibiotic resistance on first cut hay.

Multi-UAV Specification and Control with a Single Pilot-in-the-Loop

2020 ◽  
Vol 08 (04) ◽  
pp. 269-277
Author(s):  
Patricio Moreno ◽  
Santiago Esteva ◽  
Ignacio Mas ◽  
Juan I. Giribet
Keyword(s):  
Remote Control ◽  
Unmanned Aerial Vehicles ◽  
Field Experiments ◽  
Aerial Vehicles ◽  
Simulated Environment ◽  
Aerial Vehicle ◽  
Space Formulation ◽  
Trajectory Following ◽  
And Control ◽  
Multi Uav

This work presents a multi-unmanned aerial vehicle formation implementing a trajectory-following controller based on the cluster-space robot coordination method. The controller is augmented with a feed-forward input from a control station operator. This teleoperation input is generated by means of a remote control, as a simple way of modifying the trajectory or taking over control of the formation during flight. The cluster-space formulation presents a simple specification of the system’s motion and, in this work, the operator benefits from this capability to easily evade obstacles by means of controlling the cluster parameters in real time. The proposed augmented controller is tested in a simulated environment first, and then deployed for outdoor field experiments. Results are shown in different scenarios using a cluster of three autonomous unmanned aerial vehicles.

Cocklebur Control in Soybeans as Affected by Cultivars, Seeding Rates, and Methods of Weed Control

Weed Science ◽  
1975 ◽  
Vol 23 (5) ◽  
pp. 386-390 ◽  
Author(s):  
C. G. Mcwhorter ◽  
W. L. Barrentine
Keyword(s):  
Glycine Max ◽  
Weed Control ◽  
Field Experiments ◽  
Soybean Cultivar ◽  
Row Width ◽  
And Control

Four field experiments were conducted to study the effects of row width, cultivation, soybean population, soybean cultivar, and herbicides on soybean [Glycine max(L.) Merr.] yields and control of common cocklebur (Xanthium pensylvanicumWallr.). When the same herbicide practices were applied to all treatments, common cocklebur was controlled better in soybeans planted in 100-cm rows and grown with cultivation than in those planted in 18 or 33-cm rows and grown without cultivation. Increased soybean yields and better common cocklebur control were obtained when soybean populations were increased from 80,000 to 350,000 plants/ha. Common cocklebur reduced the yield of ‘Bragg’, one of the most competitive cultivars, 7% when grown in 100-cm rows with cultivation and 39% when grown in 33-cm rows without cultivation. The yields of six other cultivars were reduced about 20% in 100-cm rows and 32% to 52% in 33-cm rows. Cross cultivation controlled common cocklebur more effectively than did conventional cultivation in 100-cm rows, but cross cultivation was not advantageous when metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)one] and bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] were applied.

scholarly journals Planting Density Induced Changes in Cotton Biomass Yield, Fiber Quality, and Phosphorus Distribution under Beta Growth Model

Agronomy ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 500 ◽  
Author(s):  
Aziz Khan ◽  
Xiangjun Kong ◽  
Ullah Najeeb ◽  
Jie Zheng ◽  
Daniel Kean Yuen Tan ◽  
...  
Keyword(s):  
Field Experiments ◽  
Biomass Yield ◽  
Accumulation Rate ◽  
Fiber Quality ◽  
Phosphorus Uptake ◽  
Biomass Accumulation ◽  
Planting Density ◽  
Maximum Height ◽  
Low Density ◽  
Moderate Density

High input costs combined with multiple management and material inputs have threatened cotton productivity. We hypothesize that this problem can be addressed by a single fertilization at flowering with late sowing in a moderately populated plant stand. Field experiments were conducted to evaluate the cotton biomass accumulation, phosphorus dynamics, and fiber quality under three planting densities (low, 3 × 104; moderate, 6 × 104; and dense, 9 × 104 ha−1) and two cultivars (Zhongmian-16 and J-4B). High planting density had 6.2 and 12.6% larger stems and fruiting nodes m−2, while low density produced a 37.5 and 59.4% maximum height node ratio. Moderate density produced 26.4–15.5%, 24.7–12.6%, and 10.5–13.6% higher biomass accumulation rate at the peak bloom, boll set, and plant removal stages over low and high density in both years, respectively. J-4B produced a higher reproductive organs biomass yield when compared with Zhongmian-16 in both years. This higher biomass formation was due to both the higher average (0.8 VT kg·ha−1·d−1) and maximum (1.0 VM kg·ha−1·d−1) reproductive organ phosphorus uptake, respectively. Plants with low density had 5.3–18.5%, 9.5–15%, and 7.8–12.8% greater length, strength, and micronaire values over moderate and dense plants, respectively. Conclusively, moderate density with J-4B is a promising option for improved biomass, phosphorus acquisition, and fiber quality under a short season.

scholarly journals Effective Preemergence and Postemergence Herbicide Programs for Kochia Control

2015 ◽  
Vol 29 (1) ◽  
pp. 24-34 ◽  
Author(s):  
Vipan Kumar ◽  
Prashant Jha
Keyword(s):  
Field Experiments ◽  
Agricultural Research ◽  
Residual Activity ◽  
Acetolactate Synthase ◽  
Test Site ◽  
Herbicide Resistant ◽  
Greenhouse Study ◽  
Chemical Fallow ◽  
Herbicide Programs ◽  
Crop Competition

Field experiments were conducted in 2011 through 2013 at the MSU Southern Agricultural Research Center near Huntley, MT, to evaluate the effectiveness of various PRE and POST herbicide programs for kochia control in the absence of a crop. PRE herbicides labeled for corn, grain sorghum, soybean, wheat/barley, and/or in chemical fallow were applied at recommended field-use rates. Acetochlor + atrazine,S-metolachlor + atrazine + mesotrione, and sulfentrazone applied PRE provided ≥91% control of kochia at 12 wk after treatment (WAT). Metribuzin, metribuzin + linuron, and pyroxasulfone + atrazine PRE provided 82% control at 12 WAT. PRE control with acetochlor + flumetsulam + clopyralid, pyroxasulfone alone, and saflufenacil + 2,4-D was ≤23% at 12 WAT. Paraquat + atrazine, paraquat + linuron, and paraquat + metribuzin controlled kochia ≥98% at 5 WAT. POST control with bromoxynil + fluroxypyr, paraquat, tembotrione + atrazine, and topramezone + atrazine treatments averaged 84% at 5 WAT, and did not differ from glyphosate. Control with POST-applied bromoxynil + pyrasulfotole, dicamba, diflufenzopyr + dicamba + 2,4-D, saflufenacil, saflufenacil + 2,4-D, saflufenacil + linuron was 67 to 78% at 5 WAT. Because of the presence of kochia resistant to acetolactate synthase-inhibiting herbicides at the test site, cloransulam-methyl was not a viable option for kochia control. In a separate greenhouse study, kochia accessions showed differential response to the POST herbicides (labeled for corn or soybean) tested. Tembotrione + atrazine, topramezone + atrazine, lactofen, or fomesafen effectively controlled the glyphosate-resistant kochia accession tested. Growers should utilize these effective PRE- or POST-applied herbicide premixes or tank mixtures (multiple modes of action) to control herbicide-resistant kochia accessions in the field. PRE herbicides with 8 wk of soil-residual activity on kochia would be acceptable if crop competition were present; however, a follow-up herbicide application may be needed to obtain season-long kochia control in the absence of crop competition.

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