Control plots of Triticum aestivum var. Manitou were grown adjacent to every plot of breeding material in three hard red spring wheat nurseries at the University of Manitoba. Simple correlations between yields were high (r =.88,.87 and.63) and significant (P.01) for control plots at 2.7-m (9-ft) centers but decreased rapidly to nonsignificance with increasing distance between plot centers. The data indicate that for the particular type of plot used, the yield of a control plot provides a good measure of the soil fertility in terms of the yielding ability of an adjacent plot.