The organic community has soundly rejected the use of genetically modified crops, and current organic standards do not permit genetically modified crops to be marketed as organic, even if they are grown without harmful pesticides or artificial fertilizers.
The reasons include the fact that genetic modification can come with unknown risks to the environment and that genetic modification alters plants in ways that many people feel are more extreme or unnatural than alterations that are brought about through selective breeding. I would put this in terms of "purity," a concept like "natural" or "disgusting" which seems to relate entirely to the eye of the beholder.
However, genetic modification also opens up opportunities which can contribute to long-term sustainable agriculture, according to the authors of Tomorrow's Table: Organic Farming, Genetics, and the Future of Food. For instance, if a variety of rice were genetically modified to make it flood tolerant, then instead of using herbicides that might have negative health consequences, farmers could flood fields to kill weeds. There might also be the possibility of genetically modifying crops so that they are tolerant of marginal growing conditions, permitting them to be grown without the use of high levels of artificial fertilizers.
My inclination is to be open-minded and even enthusiastic about the possibilities of genetic engineering, and I would argue that skepticism about the technology should be based in empirical arguments. If it provides a solution that solves a real problem, then I don't think the argument from purity is strong enough to give us reason to put on the brakes. Likewise, from a biological standpoint, genetic engineering seems to be different in kind but not degree from conventional breeding (even when genes from vastly different species are intermingled). Therefore, it extends problems that we already have without introducing new problems.However, the gravity of those problems should not be underestimated, and neither should their nature as social and legal, rather than technical, problems. The problem is not how to physically grow enough nutrients for poor populations, but how to introduce stability and universal access into their food system. This is a problem that genetic engineering of crops will probably exacerbate rather than solve, as long as our patent system discourages creativity and as long as markets control the options of poor farmers.