Calgary-Agrium Inc. confirmed last week that it has formed a joint venture with Helena Chemical Co., Memphis, Tenn., to procure crop protection products. As a result, Agrium units Western Farm Service and Crop Production Services will be leaving Tenkoz Inc., Alpharetta, Ga., which was formed in 1983 to purchase crop protection chemicals for some 18 major distribution companies. Tenkoz combined purchases represent about 25 percent of the U.S. crop protection market and 800 retail locations, 200 warehouses, and 2,200 field representatives. Tenkoz will have 16 remaining members, including Wilbur Ellis, Britz, J.R. Simplot Co., Dune, West Central, Van Diest, Kova, Rosens, Estes, Big Rivers, Diamond R, Meherrin, Cardinal, Coastal, Triangle, and Jimmy Sanders.