I wrote earlier about a possible strike at three of Potash of Saskatchewan's (POT) mines. As of August 7, the miners are on strike. In morning trading, Potash is in the low $170s (down 3 to 4%), and has touched 169.
I don't think the strike is affecting the stock's price yet, as Mosaic (MOS) is lower by around the same percentage. The price of oil dropped today. Agriculture prices have also slumped. These are the most likely causes. However, should the strike be lengthy, POT might fall more. I'll evaluate the stock again if it gets to $150.
The company's strike updates are here.