Herbicide and Insecticide Use on GMO Crops …

Herbicide resistance, like antibiotic resistance in bacteria, is an evolutionary process.

Herbicide Tolerant Wheat | Calyxt

Glyphosate, the active ingredient in the weed killer sold under the name RoundUp, is the most widely used herbicide in the United States, but some plants have grown resistant to it. This has caused farmers to turn to additional herbicides. While the mechanisms that have led to resistance are not fully known, Bill Johnson, a professor of weed science; Steve Hallett, an associate professor of weed science; and Jessica Schafer, a graduate student in botany and plant pathology, believe that soil microbes may play a role.

Six cover crops, including winter wheat, were evaluated by Auburn researchers to test their tolerance to residual herbicides.

AgBioForum 12(3&4): Glyphosate-Resistant Crops and …

Herbicide tolerance in plants is not new. For many years, scientists and farmers have known that herbicide tolerance can be transferred from one plant to another through crossbreeding, in farmed crops and in wild plants. People have been observing, studying, and managing the transfer of herbicide tolerance for a long time-long before the techniques of modern biotechnology were used to genetically modify plants to have these characteristics. And scientists continue to study this.

Fennimore S, Smith R, Strange M. 2014. Sidebar: Herbicide-resistant weeds unlikely in vegetable crops. Calif Agr 68(4):150-151. .

"The main thing growers should think about with herbicides is changing the mode of action to help reduce the risk of weeds developing resistance," says Murray Hartman, oilseeds specialist with Alberta Agriculture, Food and Rural Development (AAFRD).

Fennimore S, Smith R, Strange M. 2014. Sidebar: Herbicide-resistant weeds unlikely in vegetable crops. Calif Agr 68(4):150-151. .


Herbicide Tolerant (HT) Crops - Applications and …

Preirrigation before final seedbed preparation is a common practice, as it stimulates a weed flush a few days after watering. As soon as the weeds have emerged and the field is dry enough to enter, the grower uses shallow cultivation, flaming or a nonselective herbicide to remove the new weeds. Research has shown this technique to provide 15% to 50% control of weeds in crops like lettuce (). The combination of stale seedbed technique and both herbicides and cultivation often results in good weed control.

Genetically Modified Organisms | Herbicide Tolerant Crops

One category of herbicide used in vegetable crops is fumigants, such as metam potassium, which is applied 14 to 21 days before planting to kill weed seeds and germinating seedlings. After planting, soil-active herbicides like pronamide (used in artichokes and head lettuce) and S-metolachlor and trifluralin (used in tomatoes and peppers) are applied to provide preemergence control of weeds. Postemergence herbicides are utilized in some crops; examples include clethodim, used to control emerged grass weeds in many broadleaf vegetable crops, and oxyfluorfen and bromoxynil, used to control broadleaf weeds. Many vegetable herbicides were developed in the 1960s and 1970s and include products like DCPA (used in broccoli and onion), napropamide (used in tomatoes and peppers) and linuron (used in asparagus and celery). Given the complexity of the vegetable weed control program and the extensive use of cultivation and hand-weeding, the selective pressure on weeds from vegetable herbicides is very light, despite their decades of use.

Herbicide Tolerant Crops - Cooperative Extension: Agriculture

One category of herbicide used in vegetable crops is fumigants, such as metam potassium, which is applied 14 to 21 days before planting to kill weed seeds and germinating seedlings. After planting, soil-active herbicides like pronamide (used in artichokes and head lettuce) and S-metolachlor and trifluralin (used in tomatoes and peppers) are applied to provide preemergence control of weeds. Postemergence herbicides are utilized in some crops; examples include clethodim, used to control emerged grass weeds in many broadleaf vegetable crops, and oxyfluorfen and bromoxynil, used to control broadleaf weeds. Many vegetable herbicides were developed in the 1960s and 1970s and include products like DCPA (used in broccoli and onion), napropamide (used in tomatoes and peppers) and linuron (used in asparagus and celery). Given the complexity of the vegetable weed control program and the extensive use of cultivation and hand-weeding, the selective pressure on weeds from vegetable herbicides is very light, despite their decades of use.

Herbicide Tolerance - Seed Biotechnology Center

Preirrigation before final seedbed preparation is a common practice, as it stimulates a weed flush a few days after watering. As soon as the weeds have emerged and the field is dry enough to enter, the grower uses shallow cultivation, flaming or a nonselective herbicide to remove the new weeds. Research has shown this technique to provide 15% to 50% control of weeds in crops like lettuce (). The combination of stale seedbed technique and both herbicides and cultivation often results in good weed control.