Fall applications of MCPA to improve tiller synchrony and reduce lodging in winter wheat

Abstract

Poor developmental spike synchrony in wheat (Triticum aestivum L.) can reduce the effectiveness of chemical treatments keyed on reproductive events. The broadleaf herbicide (2-methyl-4-chlorophenoxy) acetic acid (MCPA) can be used to retard the development of wheat tillers if applied to winter wheat in the fall prior to the initiation of tiller primordia. Fall applications of 0.5 kg ha−1 MCPA were sufficient to reduce the tillering rate by 20–30% while providing a slight, but statistically non-significant, increase in yield. Significant increases in kernels spike−1 were observed in the MCPA treatments. The effect of MCPA on kernels spike −1 could be modulated by nitrogen fertility and planting density. A linear relationship between spike number m−2 and planting density could be observed with MCPA treatments. Reductions in total number of spikes m−2, but an increase in kernels spike−1, resulted in significant improvements in tiller synchrony. Improved tiller synchrony is important in optimizing chemical treatments where applications are based on the developmental stages of the spike. Significant reductions in plant height and subsequent reductions in lodging under high nitrogen fertility and high plant populations were observed with MCPA treatments.