Nature discusses some possible planetary disasters, including supervolcanoes; fungal diseases attacking crops and animals; solar flares, asteroid impacts and y-ray bursts; and submarine landslides producing large tsunamis. The article notes the following about fungal diseases:
... fungi are the planet's biggest killers. Of all the pathogens being tracked, fungi have caused more than 70% of the recorded global and regional extinctions, and now threaten amphibians, bats and bees. ...
Potato blight is still a threat: 13_A2, a highly aggressive strain of P. infestans, is now rampant in Europe and North Africa. Across the globe, Phytophthora causes some US$6.7 billion in annual damages, according to a 2009 estimate. Sarah Gurr, a plant pathologist at the University of Oxford, UK, estimates that the worst theoretical potato infestation would deprive 1.3 billion people of food each year. Other major staple crops face similar threats, such as rice blast (Magnaporthe oryzae), corn smut (Ustilago maydis), soya bean rust (Phakopsora pachyrhizi) and wheat stem rust (Puccinia graminis). The stem-rust superstrain Ug99 has in recent years slashed yields in parts of Africa by as much as 80%.
If all five crop staples were hit with fungal outbreaks at the same time, more than 60% of the world's population could go hungry, says Gurr. ...
... Humans have cause for concern as well. In the past decade, a tropical fungus called Cryptococcus gattii has adapted to thrive in cooler climes and invaded the forests of North America's Pacific Northwest. By 2010, it had infected some 280 people, dozens of whom died. ...
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