Why is that not an issue with traditional crops? At least with GM crops if there is a known blight you can introduce traits that confer resistance to said blight in a much faster process than attempting to cross a high yielding and blight resistant strain and getting both favorable phenotypes in your crops. Especially with crops where it can take years for the progeny to reach maturity to even assess the phenotypes of the hybrids.
GM crops have significantly less genetic diversity simply as a result of how their created and sold. This isn’t a new problem, but fixing it significantly slows time to market.
As to using GM to add blight resistance, that’s not always an option. Cavendish bananas for example are at massive risk from Panama disease TR4 and have been for years.
I'm glad you brought up the Canvendish, what an excellent recent example of the success of genetic tools in agriculture. There are other bananas that are resistant to panama disease but have other traits such as thinner skin that make them unfit for export. In fact, researchers have turned to genetic modification, and created a Cavendish variety that is resistant to Panama disease by introducing a blight resistant gene from a blight resistant wild banana. (1) This is just one example of how we can use genetic tooling to do what would otherwise take a breeder a lifetime of work in the field with a single cross and generation of progeny per growing season.
You can develop GM crops that harbor genetic diversity. You can mutagenize them to introduce random variation and yield a variety of novel phenotypes that can adapt to any sort of conditions. You can conduct analysis using statistical models to identify the genes and regulatory mechanisms involved with these phenotypes. You can introduce these phenotypes into your cultivar. You can cross your cultivar with wild landraces to introduce more diversity, and cross these with geographically distant populations to introduce more divergent and diverse genetic compositions than what would even be possible among the landraces. To put it simply, the box has been opened, and you can do pretty much anything to shape and alter the plant with genetic tooling.
They have gotten it to work, but they are expanding trials "over the next 5 years" in the article, which means they aren't going to publish those results until 2022 at the earliest after those 5 years. You don't get published in Nature because you didn't get it to work.
> GM crops have significantly less genetic diversity simply as a result of how their created and sold. This isn’t a new problem, but fixing it significantly slows time to market.
The Cavendish is an excellent counterpoint actually - monocropping is not at all en exclusive GMO phenomenon. Naturally selected cultivars like the Cavendish are all identical clones.
This is very common across many different types of produce, and all without GE.
The same solutions for diversity work for cultivars as well as GMO seed.