Response and Survival of Rosette-Stage Horseweed (Conyza canadensis) after Exposure to 2,4-D

Weed Science ◽  
2008 ◽  
Vol 56 (5) ◽  
pp. 748-752 ◽  
Author(s):  
Greg R. Kruger ◽  
Vince M. Davis ◽  
Stephen C. Weller ◽  
William G. Johnson
Keyword(s):  
Dose Response ◽  
Growth Suppression ◽  
Conyza Canadensis ◽  
Visible Injury ◽  
Susceptible Population ◽  
Soybean Production ◽  
No Till ◽  
Dose Response Study

2,4-D is often used as a preplant burndown herbicide to help control horseweed and other broadleaf weeds before planting in no-till corn and soybean production. Isolated instances of poor horseweed control have occurred in production fields. The objective of this research was to evaluate the response of various horseweed populations to 2,4-D. In the first study, 478 horseweed populations from Indiana were subjected to 280 g ae ha−1of 2,4-D amine in the greenhouse. This rate of 2,4-D caused visible injury and prevented all biotypes from forming new leaves for 28 days. There were specific populations where all plants sprayed were alive at 28 days after treatment (DAT), and approximately 10% of all populations had a least one plant that survived 280 g ae ha−12,4-D, resumed growth, and produced seed. In a dose-response study, we observed populations with three-fold more tolerance to 2,4-D. The most tolerant population had a GR90of 513 g ae ha−1and the most susceptible population had a GR90of 121 g ae ha−1based on dry weights. Growth suppression with 2,4-D was not affected by rosette size for rosettes between 0.5 and 10 cm in width.

Glyphosate-Resistant Horseweed (Conyza canadensis) Dose Response to Saflufenacil, Saflufenacil plus Glyphosate, and Metribuzin plus Saflufenacil plus Glyphosate in Soybean

Weed Science ◽  
2016 ◽  
Vol 64 (4) ◽  
pp. 727-734 ◽  
Author(s):  
Christopher M. Budd ◽  
Nader Soltani ◽  
Darren E. Robinson ◽  
David C. Hooker ◽  
Robert T. Miller ◽  
...  
Keyword(s):  
Dose Response ◽  
Weed Management ◽  
Mode Of Action ◽  
Management Strategy ◽  
Effective Rate ◽  
Conyza Canadensis ◽  
No Till ◽  
Herbicide Mixture

The control of glyphosate-resistant (GR) horseweed (Conyza canadensis) in soybean has been variable with glyphosate plus saflufenacil. The objective of this research was to determine the biologically effective rate (BER) of saflufenacil, saflufenacil mixed with glyphosate, and metribuzin mixed with saflufenacil and glyphosate applied preplant (PP) for the control of GR horseweed in no-till soybean; a study was conducted to determine each of the three treatments. For each study, seven field sites infested with GR horseweed were used over a 2-yr period (2014, 2015). Saflufenacil alone at 25 and 36 g ai ha–1 provided 90 and 95% control of GR Horseweed 8 wk after application, while the BER to achieve 98% control was outside of the treatment range tested. The saflufenacil plus glyphosate (900 g ai ha–1) BER experiment found less saflufenacil was required as 25, 34, and 47 g ha–1 provided 90, 95, and 98% control of GR horseweed respectively. The metribuzin BER experiment found 61, 261, and 572 g ha–1 was required to provide 90, 95 and 98% control of GR horseweed, respectively, mixed with saflufenacil (25 g ha–1) and glyphosate (900 g ha–1). The addition of metribuzin with the recommended rate of saflufenacil (25 g ha–1) plus glyphosate improved control and a second effective herbicide mode of action for the control of GR horseweed. The use of a threeway herbicide mixture can be an effective weed management strategy to control GR horseweed in soybean.

A Waterhemp (Amaranthus tuberculatus) Population Resistant to 2,4-D

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 379-384 ◽  
Author(s):  
Mark L. Bernards ◽  
Roberto J. Crespo ◽  
Greg R. Kruger ◽  
Roch Gaussoin ◽  
Patrick J. Tranel
Keyword(s):  
Dose Response ◽  
Dry Weight ◽  
Population Based ◽  
Susceptible Population ◽  
Herbicide Resistant ◽  
Synthetic Auxins ◽  
Resistant Population ◽  
Amaranthus Tuberculatus ◽  
Susceptible Populations ◽  
Dose Response Study

A waterhemp population from a native-grass seed production field in Nebraska was no longer effectively controlled by 2,4-D. Seed was collected from the site, and dose-response studies were conducted to determine if this population was herbicide resistant. In the greenhouse, plants from the putative resistant and a susceptible waterhemp population were treated with 0, 18, 35, 70, 140, 280, 560, 1,120, or 2,240 g ae ha−12,4-D. Visual injury estimates (I) were made 28 d after treatment (DAT), and plants were harvested and dry weights (GR) measured. The putative resistant population was approximately 10-fold more resistant to 2,4-D (R:S ratio) than the susceptible population based on both I50(50% visual injury) and GR50(50% reduction in dry weight) values. The R:S ratio increased to 19 and 111 as the data were extrapolated to I90and GR90estimates, respectively. GR50doses of 995 g ha−1for the resistant and 109 g ha−1for the susceptible populations were estimated. A field dose-response study was conducted at the suspected resistant site with 2,4-D doses of 0, 140, 280, 560, 1,120, 2,240, 4,480, 8,960, 17,920, and 35,840 g ha−1. At 28 DAT, visual injury estimates were 44% in plots treated with 35,840 g ha−1. Some plants treated with the highest rate recovered and produced seed. Plants from the resistant and susceptible populations were also treated with 0, 9, 18, 35, 70, 140, 280, 560, or 1,120 g ae ha−1dicamba in greenhouse bioassays. The 2,4-D resistant population was threefold less sensitive to dicamba based on I50estimates but less than twofold less sensitive based on GR50estimates. The synthetic auxins are the sixth mechanism-of-action herbicide group to which waterhemp has evolved resistance.

Rapid Assay Evaluation of Plant Response to Protoporphyrinogen Oxidase (Protox)-Inhibiting Herbicides

2006 ◽  
Vol 20 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Jeanne S. Falk ◽  
Kassim Al-Khatib ◽  
Dallas E. Peterson
Keyword(s):  
Dose Response ◽  
Electrolyte Leakage ◽  
Visible Injury ◽  
Protoporphyrinogen Oxidase ◽  
Common Waterhemp ◽  
Leaf Discs ◽  
Rapid Assay ◽  
Wild Mustard ◽  
Whole Plant ◽  
Dose Response Study

Protoporphyrinogen oxidase (protox)-inhibiting herbicides damage cell membranes, resulting in electrolyte leakage. A whole-plant dose-response study and a rapid assay that measured electrolyte leakage was used to determine the response of wild mustard, soybean, and protox inhibitor–susceptible and protox inhibitor–resistant common waterhemp to increasing doses of three protox inhibitors: acifluorfen, fomesafen, and sulfentrazone. For the dose-response study, whole plants were treated with the three protox-inhibitor herbicides. Electroconductivity assay 1 consisted of cutting discs from leaf tissue and submerging them in an incubation medium containing concentrations of acifluorfen, fomesafen, or sulfentrazone. In electroconductivity assay 2, the entire leaf was treated with solutions containing acifluorfen, fomesafen, or sulfentrazone. The whole-plant dose-response study showed increasing visible injury with increasing herbicide rates for all species and all herbicides. The order of visible injury was wild mustard > susceptible common waterhemp > resistant common waterhemp > soybean. In assay 1, electrolyte leakage from leaf discs treated with acifluorfen or fomesafen increased with increasing herbicide concentrations, and was similar for all species. In contrast, electrolyte leakage from leaf discs treated with sulfentrazone did not increase with increasing herbicide concentrations for any species. In assay 2, only wild mustard leaf discs increased in electrolyte leakage with increasing herbicide rates of acifluorfen, fomesafen, and sulfentrazone and followed the regression curves established by the whole-plant dose-response study. However, assay 2 was not able to distinguish between susceptible wild mustard and tolerant soybean, or between susceptible and resistant waterhemp.

Control of Horseweed (Conyza canadensis) with Growth Regulator Herbicides

2010 ◽  
Vol 24 (4) ◽  
pp. 425-429 ◽  
Author(s):  
Greg R. Kruger ◽  
Vince M. Davis ◽  
Stephen C. Weller ◽  
William G. Johnson
Keyword(s):  
Field Study ◽  
Growth Regulators ◽  
Dose Response ◽  
Growth Regulator ◽  
The Other ◽  
Conyza Canadensis ◽  
Appropriate Use ◽  
Dose Response Study

The growth regulator herbicides 2,4-D and dicamba are used to control glyphosate-resistant horseweed before crops are planted. With the impending release of 2,4-D–resistant and dicamba-resistant crops, use of these growth regulator herbicides postemergence will likely increase. The objective of this study was to determine the effectiveness of various growth regulators on Indiana horseweed populations. A greenhouse dose–response study was conducted to evaluate the effectiveness of 2,4-D ester, diglycolamine salt of dicamba, and dimethylamine salt of dicamba on control of four populations of horseweed in the greenhouse. Population 66 expressed twofold levels of tolerance to 2,4-D ester and diglycolamine salt of dicamba. Population 43 expressed an enhanced level of tolerance to diglycolamine salt of dicamba but not to the other herbicides. Diglycolamine salt of dicamba provided the best overall control of populations 3 and 34. Additionally, a field study was conducted to evaluate standard use rates of 2,4-D amine, 2,4-D ester, diglycolamine salt of dicamba, and dimethylamine salt of dicamba on control of various sized glyphosate-resistant horseweed plants. Control of plants 30 cm or less in height was 90% or greater for all four herbicides. On plants greater than 30 cm tall, diglycolamine salt of dicamba provided 97% control while 2,4-D amine provided 81% control. Diglycolamine salt of dicamba provided the highest level of control of glyphosate-resistant horseweed, followed by dimethylamine salt of dicamba, 2,4-D ester and 2,4-D amine, respectively. This research demonstrates that horseweed populations respond differently to the various salts of 2,4-D and dicamba, and it will be important to determine the appropriate use rates of each salt to control glyphosate-resistant horseweed.

scholarly journals First case of Conyza canadensis from Hungary with multiple resistance to glyphosate and flazasulfuron

2018 ◽  
Author(s):  
Candelario Palma-Bautista ◽  
Behroz Khalil Tahmasebi ◽  
Pablo Tomás Fernández-Moreno ◽  
Antonia María Rojano-Delgado ◽  
Ricardo Alcántara de la Cruz ◽  
...  
Keyword(s):  
Dose Response ◽  
Shikimic Acid ◽  
Multiple Resistance ◽  
Conyza Canadensis ◽  
Herbicide Application ◽  
Susceptible Population ◽  
First Case ◽  
Acid Accumulation ◽  
Agricultural Areas ◽  
Als Inhibitor

Conyza canadensis is a species invading large agricultural areas throughout the world, mainly to its ability to evolve herbicide resistance. Specifically, in Hungary, extensive areas have been infested by this species due to the difficulty in controlling it with glyphosate. To corroborate this fact as resistance and not as an incorrect herbicide application, eight suspicious glyphosate-resistant C. canadensis populations from different Hungarian regions were studied. In dose-response assays with glyphosate, the LD50 and GR50 values indicated that populations 1 to 5 were resistant to this herbicide (H-5 population the most resistant). Besides, the shikimic acid accumulation tests corroborated the results observed in the dose-response assays. 11 alternative herbicides from 6 different mode of action (MOA) were applied at field doses as control alternatives on populations H-5 and H-6 (both in the same regions). The H-5 population showed an unexpected resistance to flazasulfuron (ALS-inhibitor). The ALS enzyme activity studies indicated that the I50 for H-5 was 63.3 fold higher compared to its correspondent susceptible population (H-6). Therefore, the H-5 population exhibited multiple-resistance to flazasulfuron and glyphosate, being the first case reported in Europe for this two MOA. For that reason, the other herbicides with different MOA have to be tested here.

scholarly journals First Case of Conyza canadensis from Hungary with Multiple Resistance to Glyphosate and Flazasulfuron

Agronomy ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 157 ◽  
Author(s):  
Candelario Palma-Bautista ◽  
Behroz Khalil Tahmasebi ◽  
Pablo Tomás Fernández-Moreno ◽  
Antonia M. Rojano-Delgado ◽  
Ricardo Alcántara de la Cruz ◽  
...  
Keyword(s):  
Dose Response ◽  
Shikimic Acid ◽  
Multiple Resistance ◽  
Conyza Canadensis ◽  
Poor Control ◽  
Susceptible Population ◽  
First Case ◽  
Whole Plant ◽  
Acid Accumulation ◽  
Als Inhibitor

Conyza canadensis is a species invading large areas throughout the world, mainly due to its ability to evolve herbicide resistance. In Hungary, extensive areas have been infested by this species due to the difficulty in controlling it with glyphosate. To determine whether poor control was a result of misapplication or glyphosate resistance, eight suspected glyphosate-resistant C. canadensis populations from different Hungarian regions were studied. In whole-plant dose-response assays with glyphosate, the LD50 and GR50 values (survival and fresh weight reduction at 50% relative to the untreated control, respectively) indicated that resistance was confirmed in five of the eight populations (H-5 population being the most resistant). Additionally, the shikimic acid accumulation tests corroborated the results observed in the dose–response assays. 11 alternative herbicides from six different modes of action (MOA) were applied at field doses as control alternatives on populations H-5 and H-6 (both in the same regions). The H-5 population showed an unexpected resistance to flazasulfuron (ALS-inhibitor). The ALS enzyme activity studies indicated that the I50 for H-5 with flazasulfuron was 63.3 times higher compared to its correspondent susceptible population (H-6). Therefore, the H-5 population exhibited multiple-resistance to flazasulfuron and glyphosate, being the first case reported in Europe for these two MOA.

DISTRIBUSI DAN IDENTIFIKASI POPULASI SINTRONG (Crossocephalum crepidiodes.Benth) RESISTEN PARAKUAT PADA LAHAN JAGUNG (Zea mays) DI KABUPATEN DAIRI

2017 ◽  
Vol 4 (2) ◽  
pp. 149-161
Author(s):  
Berton Sianturi
Keyword(s):  
Zea Mays ◽  
Dose Response ◽  
High Resistance ◽  
Block Design ◽  
Recommended Dose ◽  
Second Step ◽  
Resistance Level ◽  
Susceptible Population ◽  
Randomized Complete Block Design ◽  
Susceptible Populations

Crassocephalum crepidioides on Cornfields in Dairi Regency had been reported tobecome more difficult to control using paraquat. The objective of the research was todetermine the characteristics and the distribution of C.crepidioides resistant to paraquatin cornfields. The experiment was carried out in two steps, the first step was screeningthe population of C. crepidioides with paraquat at the recommended dose, and the secondstep, dose-response experiment for the resistance level of C. crepidioides population withdose 0, 76, 152, 304,5, 609, 1218, and 2436 g.ai /ha. In the first step experiment, paraquatdichloride was applied at 280 g.ai/ha. The treatments were arranged in a randomized blockdesign with 3 replication. The second step experiment was that the resistant populationsconfirmed in the first experiment were sprayed for their dose-response. The treatmentswere arranged in a randomized complete block design (CRBD). The results showed thatof 30 populations of C. crepidiodes, 19 populations (63.3%) were categorized to beresistant with the mortality ranging from 10.84% to 52.08%, and 11 populations (36.7%),was categorized as high resistance with mortality of 0% to 9.21%. The level ofresistance (R/S) of R-C25, R-C27, and R-C30 populations of C. crepidioides were 12,3,14,86, and 24,83 times consecutively, compared with the susceptible population. Thenumber of C. crepidioides chlorophyl leaves in susceptible populations was significantlylower than that of a resistant populations.

Reduction of insulin clearance during hyperglycemic clamp. Dose-response study in normal humans

Diabetes ◽  
1988 ◽  
Vol 37 (10) ◽  
pp. 1351-1357 ◽  
Author(s):  
H. Tillil ◽  
E. T. Shapiro ◽  
A. H. Rubenstein ◽  
J. A. Galloway ◽  
K. S. Polonsky
Keyword(s):  
Dose Response ◽  
Insulin Clearance ◽  
Hyperglycemic Clamp ◽  
Normal Humans ◽  
Dose Response Study
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