I was in college when the first GMO seeds were made available to farmers. These were Round Up resistant soybeans invented by Monsanto. The trait was licensed to other seed companies too and in just a few years, such seeds became the standard for most soybean acres in the United States. A few years later the first GMO corn seeds became available too. The corn was given Round Up resistance, but also around the same time, another engineered trait that allowed the corn plant to produce its own insecticide, Bt.
My father and I adopted GMO soybeans right away. It is easier to have one herbicide plan that applies to all soybeans acres, especially if a herbicide that can be sprayed on only GMO soybeans with that resistant trait would kill soybeans without it. That could be a costly mistake. The switch to Round Up resistant soybeans immediately simplified our herbicide plans for soybeans. It was much easier and cheaper to have a field of soybeans that was clean of weeds. Yields went up. In the intervening years as both the conventional breeding programs and engineered traits have been improved, yields of soybeans have continued to climb.
I was a late adopter of GMO corn. For a few years I continued to grow conventional corn hybrids and sell them for a bonus as non-GMO corn. But as the hybrids with engineered traits continued to improve, the math no longer favored growing non-GMO corn. The loss of potential yield more than made up for the paltry bonus being paid for selling non-GMO corn. So I too switched to Round Up resistant, engineered hybrids that also produced their own Bt insecticide. As with soybeans, the yields went up and have continued to trend upwards as both the breeding programs and engineering have been improved.
Both corn and soybean acres in the United States are overwhelmingly GMO these days. These varieties of soybeans and hybrids of corn are far more reliable crops than their non-GMO alternatives. Part of this is that the conventional breeding programs for all the major seed producers are focused on providing the best lineages to be further modified by genetic engineering. But a large part of this is that the engineered traits themselves boost yields, increase the crop's resistance to drought, disease, and pests, and open up methods of weed control to farmers that allow us to better control weeds. All of that increases the yield we can reliably expect.
Whether or not the plant is GMO, whatever herbicides are used will eventually become less effective because the weeds are under tremendous selective pressure to evolve resistance to that herbicide. This played out in the 70s and 80s as herbicides in common use became less effective, leading to the development of GMO crops that could then be sprayed with herbicides that the weeds weren't resistant to. Well, that is happening again now. Round Up is getting less effective. So new soybeans are being developed that can resist other herbicides in addition to Round Up to reduce weed pressure in fields. It is an arms race of sorts, between the genetic engineers and the evolution of weeds. But so far, the scientists are winning, at least in my region where our harsh winters keep our weed pressure less than our neighbors in southern states.
I want to mention something else with regards to GMO seeds, the rumor that farmers get sued by seed companies. Where this idea comes from is that prior to GMO soybean seed, farmers tended to keep a little of their soybean grain to use as seed for the following year's crop. Soybeans aren't hybrids like corn, and what is planted will be reproduced, just in much greater quantities. With GMO seeds, farmers signed an agreement in order to buy the seed saying they wouldn't do that with their GMO seed/grain. A tiny minority of farmers cheated and got caught. An even smaller minority took advantage of cross pollination and kept for seed only the grain produced from the rows of their soybeans closest to rows of GMO soybeans – in the hope that after a few years of doing so, they would have seed with reliable GMO traits, without having had to pay for it.
Another persistent rumor is that idea that seed companies insert genes that prevent farmers from planting as seed the grain they harvested the previous year. This too is bunk. With corn the barrier is due to hybridization which has been around for 100 years, so there is no need for a so called terminator gene. With soybeans, the fact that a soybean seed makes many copies of itself that could be planted the next year is why farmers sign agreements saying they won't do that in order to buy the seed in the first place. Such agreements wouldn't be necessary if the grain was sterile, not to mention that producing the seed in the first place would be difficult or impossible if the soybean plants only produced sterile seeds.
I like GMO crops. I like that they can be made to produce reliably good yields under various stresses from drought to disease to pests. I like that they allow farmers to use herbicides that are far less toxic to humans than those in common usage in the 70s and 80s. I like that I haven't sprayed any insecticides on my corn in many years, because the plant takes care of that itself by producing the Bt toxin, the same bacteria derived toxin that organic farmers have used for decades as an insecticide spray. I like that genetic engineering provides ways of introducing traits into crops in a relatively fast, predictable way and that such traits can be removed too if a problem develops. And I have hope for the future, that engineered traits will continue to keep yields of many food crops reliable as climate change alters agriculture while the global population continues to grow.
I'm interested to see what CRISPR/cas9 enables crop scientists to do in the future. As far as I know they haven't used that technology to produce any of the developments we've seen in GMO crops so far. It takes years for a new GE trait to work its way through the regulatory process to the point that it produces a seed that I can buy. But such a precisely targeted gene editing tool ought to produce some interesting traits for future crops.