Stability of corn (Zea mays)-foxtail (Setariaspp.) interference relationships

Abstract

Variation in interference relationships have been shown for a number of crop-weed associations and may have an important effect on the implementation of decision support systems for weed management. Multiyear field experiments were conducted at eight locations to determine the stability of corn-foxtail interference relationships across years and locations. Two coefficients (IandA) of a rectangular hyperbola equation were estimated for each data set using nonlinear regression procedures. TheIandAcoefficients represent percent corn yield loss as foxtail density approaches zero and maximum percent corn yield loss, respectively. The coefficientIwas stable across years at two locations and varied across years at four locations. Maximum yield loss (A) varied between years at one location. Both coefficients varied among locations. Although 3 to 4 foxtail plants m−-1row was a conservative estimate of the single-year economic threshold (Tc) of foxtail density, variation inIandAresulted in a large variation inTc. Therefore, the utility of using common coefficient estimates to predict future crop yield loss from foxtail interference between years or among locations within a region is limited.