Growth and Seed Production of Horseweed (Conyza canadensis) Populations after Exposure to Postemergence 2,4-D

  title={Growth and Seed Production of Horseweed (Conyza canadensis) Populations after Exposure to Postemergence 2,4-D},
  author={Greg R. Kruger and Vince M. Davis and Stephen C. Weller and William G. Johnson},
  booktitle={Weed Science},
Abstract Horseweed can be a problematic weed in no-till soybean fields and populations can vary in their response to 2,4-D. The objective of this study was to evaluate the growth and seed production of four horseweed populations after exposure to 2,4-D. 2,4-D amine was applied at 0, 140, 280, and 560 g ae ha−1 to 5- to 10-cm-tall horseweed plants. An additional treatment of 280 g ha−1 of 2,4-D + 840 g ae ha−1 of glyphosate was included in the study. At 2 wk after treatment (WAT), injury ranged… 

Glyphosate-Resistant Horseweed (Conyza canadensis) Control with Dicamba in Alabama

Data confirmed that GR-1 and GR-2 horseweed populations were 3.0 to 38 times more resistant to glyphosate than the susceptible population, according to population, data type, and growth stage at treatment, and any potential resistance-management benefit of tank-mixing dicamba with glyphosate may be negated.

Response of Problematic Weed Populations in Nebraska to Glyphosate

Ninetyeight percent of the 130 horseweed populations screened would require a rate above 1262 g ae ha of glyphosate to achieve 90% control of the population; indicating a majority of the populations screened exhibited some level of glyphosate-resistance.

Control of Glyphosate-Resistant Horseweed (Conyza canadensis) with Dicamba Applied Preplant and Postemergence in Dicamba-Resistant Soybean

This technology provides a much-needed POST option of dicamba to be applied as a rescue treatment to control weed escapes caused by late emergence or poor initial control following a PP herbicide application.

Rapid Necrosis: A Novel Plant Resistance Mechanism to 2,4-D

The results indicate the first case of resistance to 2,4-D and occurrence of rapid necrosis in C. sumatrensis, and the evolution of H2O2 began at 15 min after application and was less pronounced in low light.

Control of Glyphosate-Resistant Horseweed in Winter Wheat with Pyrasulfotole Premixed with Bromoxynil

Single mode of action herbicides like 2,4-D controlled GR horseweed are recommended; however, multiple modes of action should be used to prevent populations from becoming incrementally more resistant under repeated selection pressure.

Canada fleabane (Conyza canadensis) control with preplant applied residual herbicides followed by 2,4-D choline/glyphosate DMA applied postemergence in corn

A total of five field trials were conducted over a 2-yr period in Ontario to determine the level of GR Canada fleabane control with a two-pass weed control program of a pre plant (PP) residual herbicide followed by 2,4-D choline/glyphosate dimethylamine (DMA) applied POST.

Canada fleabane (Conyza canadensis) control with preplant applied residual herbicides followed by 2,4-D choline/glyphosate DMA applied postemergence in corn

Results from this research demonstrate that residual herbicides applied PP followed by 2,4-D choline/glyphosate DMA POST provides excellent control of GR Canada fleabane, and also incorporates different modes of action thereby limiting the selection of resistant weeds.

Control of Canada fleabane (Conyza canadensis) with glyphosate DMA/2,4-D choline applications in corn (Zea mays)

Results from this research indicate that a sequential 2-pass application of glyphosate DMA/2,4-D choline provided acceptable control of GR Canada fleabane in corn.

Investigations of the sensitivity of ornamental, fruit, and nut plant species to driftable rates of 2,4-D and dicamba

Assessment of the sensitivity of driftable rates of 2,4-D and dicamba with or without glyphosate on common ornamental, fruit, and nut species indicated apple, red maple, peach, and pin oak were more sensitive to treatments containingdicamba, whereas black walnut, grapevine, and American elm were moresensitive to 2, 4-D.

Efficacy of 2,4-D Choline/Glyphosate Dimethylamine on Glyphosate Resistant Canada Fleabane (Conyza canadensis) at Different Sizes

The required dose of 2,4-D choline/glyphosate DMA was determined to provide 95% control of 10, 20 and 30 cm tall Canada fleabane in greenhouse and field experiments, respectively.



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

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 and was not affected by rosette size for rosettes between 0.5 and 10 cm in width.

Glyphosate-Resistant Horseweed (Conyza canadensis) in Mississippi1

It is demonstrated that the difficult-to-control biotypes were resistant to glyphosate, that resistant biotypes could survive glyphosate rates of up to 6.72 kg/ha, and that plant size affected both resistant and susceptible biotypes in a similar manner.

Glyphosate-resistant Horseweed (Conyza Canadensis) Emergence, Survival, and Fecundity in No-till Soybean

Research indicates that this southeast Indiana horseweed biotype behaves primarily as a summer annual weed and produces significant amounts of seed when uncontrolled in no-till soybean production.

Response of selected horseweed (Conyza canadensis (L.) Cronq.) populations to glyphosate.

Variation in glyphosate resistance was found among the populations tested and a dose response curve demonstrated that four times as much glyphosate was needed to achieve a 50% fresh weight reduction in resistant biotypes when compared to a susceptible biotype.

Frequency, Distribution, and Characterization of Horseweed (Conyza canadensis) Biotypes with Resistance to Glyphosate and ALS-Inhibiting Herbicides

The additive response between glyphosate and cloransulam indicates that, where the level of resistance is fairly low, combinations of these herbicides should be more effective for control of multiple-resistant populations compared with application of a single herbicide.

Horseweed (Conyza canadensis) control in no-tillage soybeans (Glycine max) with preplant and preemergence herbicides.

Research was conducted in 1987 and 1988 to identify effective horseweed control strategies in no-tillage soybean production. Paraquat at 560 g ai ha-1 plus metolachlor at 2200 g ai ha-1, linuron at

Resistance of Wild Carrot (Daucus carota) to 2,4-D in Michigan1

Differential response of wild carrot to 2,4-D was found in seeds collected from 10 locations in Michigan, three in Ohio, one in Illinois, and one in Ontario, Canada, and it was due to resistant individuals.

A Field Survey to Determine Distribution and Frequency of Glyphosate-Resistant Horseweed (Conyza Canadensis) in Indiana

Information gathered in this survey can assist in the development of applied research, as well as reactive glyphosate-resistant horseweed management education in the SE region of the state as a means of providing an early warning system to address glyphosate resistance in weeds.

Growth and Seed Production of Horseweed (Conyza canadensis) Populations Resistant to Glyphosate, ALS-Inhibiting, and Multiple (Glyphosate + ALS-Inhibiting) Herbicides

Untreated plants from horseweed populations that were resistant to glyphosate, ALS-inhibiting, or multiple glyphosate + ALS- inhibiting herbicides produced similar amounts of biomass and seed compared to populations that was susceptible to those herbicides or combination of herbicides.

Factors affecting germination of horseweed (Conyza canadensis)

The data suggest that even at high soil salinity conditions, horseweed can germinate, and osmotic potential increased from 0 (distilled water) to −0.8 MPa, indicating that germination can still occur under moderate water stress conditions.