Newswire18 / Ahmedabad October 1, 2008, 20:43 IST The prices of long staple Bt cotton or Sankar-6, in Gujarat are seen nose-diving 20 per cent in the next 10-15 days due to low export demand and increasing arrivals, traders said on Tuesday. Gujarat is the top cotton producing state in the country, contributing an estimated 11.5 million bales to the country