Further insight is provided regarding an appropriate model of cropwater response for continuously growing crops. A dated input.production function was estimated for pineapple oranges in Florida. Generalized least squares regression techniques were used to ameliorate the effects of contemporaneously and serially correlated errors. The continuously growing citrus crops also lead to :{ac torially determined product ion re-. lations over time. This causes the economic optimum level of water to apply in any given time period to be a function of water applied in the past and expectations for the future.