Via Wired News:

There may be less US grown organic cotton in coming years as Monsanto purchased Delta and Pine, the largest US source of cotton seeds. Contamination from engineered seeds may limit the amount of organically grown cotton available:

Among other things, the group argues that the merger could dampen the recent trend toward organic cotton.

Companies including Wal-Mart (the largest purchaser of organic cotton in the country) and Nike have ramped up their marketing and sales of organic cotton products in recent years.

But organic cotton could become more difficult to come by post-merger. With more genetically engineered varieties in fields, the risk of contamination to organic and conventional crops will likely increase.

Last year, Liberty Link rice, made by Bayer, contaminated rice in several states including Missouri and Louisiana, resulting in shipments rejected by Europe, which is largely against genetically modified crops.

(Emphasis mine.) Add cotton to the list of threatened organic crops. As safe as these big ag companies can claim they are in the lab, when they are introduced into nature, they seem to get a mind of their own.