# Horticulture/Roundup

Roundup :
| Active ingredients: | Glyphosate |
| Effect: | Systemic herbicide |
| Selectivity: | nonselective |
| Persistence: | nonpersistent |
| Application: | spray or paint |
| Ecological hazards: | Binding agents are problematic for some wildlife |
| Organic Gardening: | Not permitted |
| Inactive ingredients: | polyoxy-ethyleneamine |
Roundup is the brand name of a systemic, broad-spectrum herbicide produced by the United States company Monsanto. It is the most used herbicide in the world, and the top-selling agrichemical of all time. Monsanto developed and patented the glyphosate molecule in the 1970s, and marketed Roundup from 1973. It retained exclusive rights in the US until its US patent expired in September, 2000, and maintained a predominant marketshare in countries where the patent expired earlier.

## Uses

Weeds and grass will generally re-emerge within one to two months after usage. Because of this mode of action, it is only effective on actively growing plants; it is not effective as a pre-emergence herbicide. Due to the absorption being limited to foliage, soil-bound glyphosate is effectively inert.

## Action

The active ingredient of Roundup is the isopropylamine salt of glyphosate. Glyphosate's mode of action is to inhibit an enzyme involved in the synthesis of the amino acids tyrosine, tryptophan and phenylalanine. It is absorbed through foliage and translocated to growing points.

## Precautions

The surfactants used in the Roundup products may cause health issues. Like all herbicides, Roundup should only be applied in accordance with all labeling and legal requirements.
The US Environmental Protection Agency, the EC Health and Consumer Protection Directorate, and the UN World Health Organization have all independently concluded that glyphosate is not carcinogenic.
The toxicity of Roundup has been questioned, not so much because of its active agent (glyphosate) but because of the inactive ingredients, including the surfactant polyoxy-ethyleneamine (POEA) . These components are responsible for "acute" toxicity to humans such as eye irritation. Ingestion of Roundup has been proven to cause diarrhea following extremely high exposures.
Roundup has also been found by researchers at Texas Tech University to disrupt the expression of steroidogenic acute regulatory protein (StAR) which has a role in testosterone production in males .

## Resistance

Due to heavy use of the herbicide, and its glyphosate-tolerant counterpart plants, fears have arisen that repeated exposure and cross breeding may eventually cause unwanted plants and weeds that might mutate into Roundup tolerant forms effectively creating a superweed.

## References

* Pease W S et al. (1993) Preventing pesticide-related illness in California agriculture: Strategies and priorities. Environmental Health Policy Program Report. Berkeley, CA: University of California. School of Public Health. California Policy Seminar.
* Wang Y, Jaw C and Chen Y (1994) Accumulation of 2,4-D and glyphosate in fish and water hyacinth. Water Air Soil Pollute. 74:397-403
* Baccara, Mariagiovanna, et al. Monsanto's Roundup, NYU Stern School of Business: August 2001, Revised July 14, 2003.