Assessment of two nondestructive assays for detecting glyphosate resistance in horseweed (Conyza canadensis)

  title={Assessment of two nondestructive assays for detecting glyphosate resistance in horseweed (Conyza canadensis)},
  author={Clifford H. Koger and Dale L. Shaner and W. B. Henry and Talia Nadler-Hassar and Walter Edward Thomas and John W. Wilcut},
  booktitle={Weed Science},
Abstract Two rapid, nondestructive assays were developed and tested for their potential in differentiating glyphosate-resistant from glyphosate-susceptible biotypes of horseweed. In one assay, leaves of glyphosate-resistant and -susceptible corn, cotton, and soybean plants, as well as glyphosate-resistant and -susceptible horseweed plants, were dipped in solutions of 0, 300, 600, and 1,200 mg ae L−1 glyphosate for 3 d, and subsequent injury was evaluated. In the second assay, plant sensitivity… 
1 Citations
After Agrarian Virtue
  • J. Chen
  • Economics
    Indiana Law Review
  • 2019
What constitutes agrarian virtue? Across human or even geological history, agrarian virtue subsists in the sustained production of food, fiber, and fuel without the exhaustion of finite resources or


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.
Shikimate accumulates in both glyphosate-sensitive and glyphosate-resistant horseweed (Conyza canadensis L. Cronq.).
This direct comparison conclusively confirms that horseweed plants collected in western Tennessee in 2002 are resistant to 4 times the normal application dosage of glyphosate, implying that alternative control strategies for glyphosate-resistant horseweed will be needed in those no-tillage production systems where it commonly occurs.
Investigations into glyphosate-resistant horseweed (Conyza canadensis): retention, uptake, translocation, and metabolism
The results suggest that resistance is likely due to altered cellular distribution that impaired phloem loading and plastidic import of glyphosate resulting in reduced overall translocation as well as inhibition of EPSPS.
Resistance to glyphosate in Lolium rigidum
It is speculated that movement of glyphosate to its site of action in the plastid is involved in the resistance mechanism of annual ryegrass populations that have developed resistance to most major herbicides.
Tolerance and accumulation of shikimic acid in response to glyphosate applications in glyphosate-resistant and nonglyphosate-resistant cotton (Gossypium hirsutum L.).
Increased sensitivity to glyphosate of reproductive structures to glyphosate inhibition may be due to a higher demand for shikimate pathway products and may provide an explanation for reports of fruit abortion from glyphosate-treated GR cotton.
Rapid determination of glyphosate injury to plants and identification of glyphosate-resistant plants
A modified, simpler method of extraction and assay for detection of shikimate in plants has been adapted from previously published procedures and rapid accumulation was observed in glyphosate-sensitive plants that have been treated with glyphosate.
Effect of Glyphosate Spray Coverage on Control of Pitted Morningglory (Ipomoea lacunosa)1
Results demonstrated that inadequate control of pitted morningglory with glyphosate was more related to tolerance than glyphosate spray coverage, and glyphosate rates higher than 1.68 kg/ha may be beneficial when spray coverage is severely limited or when plants are beyond the four-leaf growth stage.
Syngenta Quick-Test: A Rapid Whole-Plant Test for Herbicide Resistance1
A diagnostic test used for testing grass weed survivors to herbicides in the field for resistance was evaluated, and the added features of the QT suggest a likely fit for in-season testing of surviving weeds and possible follow-up action.
A Rapid Method to Determine Cereal Plant Response to Glyphosate1
This method detects the differential responses of plants in 4 d, allowing for the rapid selection of glyphosate-tolerance response, and verified the tolerance level of a sensitive barley cultivar and the four tolerant and sensitive mutant lines derived from it.