Herbicide tolerance
As herbicide tolerance is defined as the insensitivity of a crop compared with a mechanism of action of a herbicide . Herbicide tolerance can be introduced into the plants either by conventional breeding (e.g. Clearfield system) or by gene modification (e.g. Roundup-Ready system). Only conventionally grown, herbicide-tolerant seeds are permitted in Europe.
The terms herbicide tolerance and herbicide resistance are usually used interchangeably, although the Weed Science Society of America (WSSA) defines the two terms differently. Herbicide resistance is defined as a genetic trait that allows a plant to survive after herbicide , which would normally kill a wild plant . This herbicide resistance can occur naturally or through genetic manipulation . In contrast to this, herbicide tolerance denotes the inherent property of a plant to survive a herbicide treatment, this tolerance being naturally present and not being triggered either by selection or by genetic manipulation.
Systems with conventionally grown seeds
Clearfield system
The Clearfield system has been marketed by BASF since 1995 . It is a specific resistance to ALS inhibitors (imidazolinones) such as B. Imazamox . Clearfield varieties are found in corn , canola , rice , sunflower , wheat and lentils .
Duo maize system
The duo system consists of cycloxydim -resistant maize varieties and has been on the market since 2000. It facilitates the control of weed grasses, but has so far not achieved any significant importance.
ExpressSun system
The ExpressSun system in sunflowers includes sulfonylurea- tolerant varieties, allowing the herbicide Tribenuron-methyl to be used for weed control. It has also not acquired much importance.
Systems with genetically modified seeds
Roundup Ready
Roundup Ready is a Monsanto system that includes glyphosate- tolerant crops. It is the most important of all herbicide tolerance systems globally and includes corn , cotton , soybean , sugar beet and peanut varieties. Due to glyphosate-resistant weeds, it is increasingly being replaced by Roundup Ready Xtend .
LibertyLink
LibertyLink was developed by Bayer CropScience in competition with Roundup Ready and offers tolerance to glufosinate ( Liberty , Basta ). The system was introduced in the USA in 2004.
Roundup Ready Xtend
Roundup Ready Xtend is an extension of Roundup Ready to include tolerance to dicamba .
Enlist
Enlist was developed by Dow AgroSciences . It includes plants tolerant of glyphosate and 2,4-D . The matching herbicide ( Enlist Duo ) contains 2,4-D as a choline salt , which has a lower volatility than other esters and salts of 2,4-D and should therefore prevent damage from drift .
Advantages and disadvantages
Herbicide-tolerant crops provide a means of combating "problem weeds" that have become resistant to several selective herbicides. In addition, due to the herbicide tolerance, certain herbicides can be used in the first place or over a longer period of time (including post-emergence ).
In the United States and South America, herbicide-tolerant seeds are mostly used to grow the same crop every year (without crop rotation ). This creates a high selection pressure on the weeds, which leads to the development of herbicide resistance if there is insufficient refuge area.
In addition, there may be problems with leftover seeds from last year's cultivation, which are more difficult to control due to the herbicide tolerance (desired in the previous year) (e.g. with volunteer rape ).
See also
Individual evidence
- ↑ http://wssa.net/wssa/weed/resistance/herbicide-resistance-and-herbicide-tolerance-definitions/
- ↑ The Clearfield® production system in rapeseed cultivation , LfL Bavaria
- ↑ DUO system: the insurance in maize against weeds that are difficult to control ( memento of the original dated November 16, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b Catrin Hahn, Hermann Krauss: Clearfield-Raps: A sensible alternative or a total loss? In: agrarheute.com . April 29, 2015 ( online ).
- ^ For Sunflower Weed Control Use DuPont ™ ExpressSun® Herbicide
- ↑ roundupreadyplus.com: Products
- ↑ LibertyLink® Cotton System
- ↑ Weed Management in LibertyLink® and Glyphosate-Tolerant Soybeans
- ↑ Darrin M. Dodds, Christopher L. Main, L. Thomas Barber, Charles Burmester, Guy D. Collins, Keith Edmisten, Daniel O. Stephenson, Jared R. Whitaker, Deborah L. Boykin: Response of LibertyLink and WideStrike Cotton to Varying Rates of Glufosinate . In: Weed Technology . tape 29 , no. 4 , October 1, 2015, p. 665-674 , doi : 10.1614 / WT-D-15-00012.1 .
- ↑ Don't Confuse RoundupReady Xtend and Enlist Crop Systems , October 2, 2014
- ↑ Additional research shows Colex-D technology greatly reduces drift ( Memento of the original from November 16, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , April 9, 2012
- ↑ CLEARFIELD winter rape: benefit and risk
- ↑ See e.g. B. Weeds Resistant to EPSP synthase inhibitors (G / 9)
- ↑ Cord Buhre, Hagen Bremer, Erwin Ladewig: Combating Clearfield® volunteer rape in sugar beet . In: Julius Kühn Archive . No. 434 , March 13, 2012, p. 443 , doi : 10.5073 / jka.2012.434.054 ( PDF ).
