One of the apocalyptic novel our host recommends is "The Death of Grass" in which a plant pathogen wipes out all species of grass creating a global food crisis.
Honestly a pathogen that wipes out an entire family of species is probably not likely (though not impossible).
But then to create a crisis it wouldn't need to.
As a species eighty percent of our plant-based food intake comes from just twelve crop species - eight grain species and four tuber species . Sixty percent comes from Rice, wheat and maize alone.
Civilization - like an army - marches on its stomach.
A global failure in just one of those three would have critical knock on effects. Imagine if a pathogen wiped out just one of those three across the globe for several years the way the European Potato Failure destroyed potato harvests in the mid-1840s (most notably in Ireland (the Great Famine) but in the rest of Northern Europe as well). Or if we got grain harvest failures across the world due to drought as happened in 2007/8 but lasting more than two years. As a result affluent countries would attempt to buy up the remaining grain driving up the price, countries that were food independent would cling on to their harvest and those dependent on imports would have a real problem. Famine would result first in developing nations but eventually even in developed nations as the remaining grain was priced out of people's hands. Meat prices would rise too because meat is so grain dependent.
Hunger is a well known catalyst of social unrest and it's likely food riots would result. If the failures were protracted then it's also likely that riots would turn into a complete breakdown of the social fabric.
A slow, messy apocalypse of the worst kind that would eat the grace period alive.
Becka