Genetic engineering (GMO) is NOT an extension of conventional plant breeding.

[pnwmom]

3. In nature, a plant can't breed with an insect, no matter how many generations are involved.

Genetically engineered foods are those that are created using specific biotech methods that aren't used in conventional plant breeding. Those are the plants that need to be labeled. It will be simple here as it is in Europe and most of the rest of the world.

From Consumers Union:

http://consumersunion.org/wp-content/uploads/2013/02/Wide-Crosses.pdf

Genetic engineering is not just an extension of conventional breeding. In fact, it differs profoundly. As a general rule, conventional breeding develops new plant varieties by the process of selection, and seeks to achieve expression of genetic material which is already present within a species. (There are exceptions, which include species hybridization, wide crosses and horizontal gene transfer, but they are limited, and do not change the overall conclusion, as discussed later.) Conventional breeding employs processes that occur in nature, such as sexual and asexual reproduction. The product of conventional breeding emphasizes certain characteristics. However these characteristics are not new for the species. The characteristics have been present for millenia within the genetic potential of the species.
Genetic engineering works primarily through insertion of genetic material, although gene insertion must also be followed up by selection.

This insertion process does not occur in nature. A gene “gun”, a bacterial “truck” or a chemical or electrical treatment inserts the genetic material into the host plant cell and then, with the help of genetic elements in the construct, this genetic material inserts itself into the chromosomes of the host plant. Engineers must also insert a “promoter” gene from a virus as part of the package, to make the inserted gene express itself. This process alone, involving a gene gun or a comparable technique, and a promoter, is profoundly different from conventional breeding, even if the primary goal is only to insert genetic material from the same species.

But beyond that, the technique permits genetic material to be inserted from unprecedented sources. It is now possible to insert genetic material from species, families and even kingdoms which could not previously be sources of genetic material for a particular species, and even to insert custom-designed genes that do not exist in nature. As a result we can create what can be regarded as synthetic life forms, something which could not be done by conventional breeding.

SNIP