Why Walmart is a Threat to Organic Food

Walmart announced recently that it is introducing an organic food line, Wild Oats, in 2000 of its stores. Some food-justice activists were excited by this announcement, but others are concerned.  Why is this not a black-and-white issue?  How could this decision by Walmart have negative consequences?
CLICK HERE to read "Why Walmart is a Threat to Organic Food" by Arun Gupta, May 1, 2014, at www.alternet.com