Tyson Foods Inc., Springdale, Ark., said it expects by July or August to close a 14-year-old deli meat plant in Ponca City, Okla., and transfer production to three other sites in Buffalo, N.Y.; Cherokee, Iowa and Houston. "After extensive consideration, we've concluded closing Ponca City and moving the production to three other plants is necessary to improve the viability of overall processed meats operations," said Dick Belsito, senior vice president of processed meats. Tyson said the move will affect approximately 580 people and that the company hopes to find a buyer for the operation.