Abstract
Palmer's z-index, calculated to reflect only the planting-emergence and anthesis-grainfill stages of the growing season, is related with detrended corn yields to produce a predictive model for Illinois corn production. The model is evaluated to see how well it can predict mean bushel per acre corn yields for large areas (state of Illinois). Results suggest the z-index, if calculated to emphasize moisture-sensitive periods in corn production, is a reliable predictor of yields, and, moreover, this predictive ability improves with more extreme moisture conditions.
