The orange industry in Florida has been experiencing a growing crisis over the last few years, as a disease has been spreading through orchards that causes the fruit to sour and turn green before it can be picked. The problem had previously been mitigated by pesticide use, but the strain of bacteria that has been responsible for the disease has evolved to be resistant to these chemicals. This has forced growers to try developing genetically modified crops that aren't susceptible to the infection, which has begun to spread throughout the world.
Genetically-modified organisms (GMO) are an extremely controversial topic with the environmental community. While proponents say the production of GMO crops could help hedge against disasters such as the one currently afflicting orange growers, opponents say that not enough is known about these plants to make them safe for widespread consumption. There are also concerns about the grip that "Big Ag" companies (i.e. large agricultural conglomerates that control the industry) have over the use of these crops.
The New York Times recently published a report about the efforts of farmers to stop the spread of the bacteria they call "citrus green", which include chopping down and burning the trees that are affected. But this hasn't slowed the spread.
As Grist, an environmental news site, points out, it is worth noting that many of these diseases that affect agriculture are themselves the result of overzealous pesticide use. As farmers use more chemicals to try battling these infections, the microbes evolve to resist the pesticide, creating a more dangerous strain that could spread even faster.