Up first, here's a fun little article. What are the most poisonous things in the world. Some of these answers might just surprise you.
(I apologize for forgetting who the HT goes to on this one. Feel free to name yourself in the comments.)
Now, you've likely heard of the Great Famine in Ireland, more commonly known as the Potato Famine. This famine was cause by a devastating blight on potatoes. The poor of the country were almost entirely dependent upon potatoes for food and millions emigrated to other countries in desperation. What you may not be aware of is that the same blight that destroyed Ireland's potatoes in 1740 is still around and it's right here in America, only this time it's main focus is tomatoes.
You may also listen here to a fascinating discussion about this blight, which will help you recognize the dangers and how to put a stop to it in your own gardens, which, for the sake of the greater good, you really must do.