 Crop-to-weedy transfer refers to the transfer of genetically modified material to a weed, and crop-to-wild indicates transfer from a genetically modified crop to a wild, undomesticated plant and/or crop.There are concerns that the spread of genes from modified organisms to unmodified relatives could produce species of weeds resistant to herbicides that could contaminate nearby non-genetically modified crops, or could disrupt the ecosystem, This is primarily a concern if the transgenic organism has a significant survival capacity and can increase in frequency and persist in natural populations.This process, whereby genes are transferred from GMOs to wild relatives, is different from the development of so-called "superweeds" or "superbugs" that develop resistance to pesticides under natural selection.