Abstract: A field study was conducted to determine the effect of increasing seed rates of spring wheat (Triticum aestivum) on redstem filaree (Erodium cicutarium) biomass and seed production and on wheat yield in a zero-tillage cropping system. Wheat was sown at 50, 100, 150, 200, and 300 kg/ha in an experiment four consecutive years to determine annual and accumulated effects over time. Redstem filaree was most competitive with wheat when it emerged before or with wheat and when rainfall was plentiful during May and June. Redstem filaree biomass and seed production were markedly inhibited by drought conditions. An increase in wheat seed rate from 50 to 300 kg/ha reduced redstem filaree biomass and seed production by 53 to 95% over the years. There was little yield benefit to increasing the seed rate of weed-free wheat above 50 kg/ha. However, in the presence of redstem filaree, an increase in wheat seed rate from 50 to 300 kg/ha resulted in wheat yield being increased by 56 to 498%. Over four consecutive years, an increase in wheat seed rate from 50 to 300 kg/ha reduced redstem filaree in the soil seedbank by 79%. Higher seed rates of wheat can be an effective component of an improved program for redstem filaree management in conservation tillage cropping systems.
Nomenclature: Redstem filaree, Erodium cicutarium (L.) L'Her. ex Ait. #3 EROCI; spring wheat, Triticum aestivum L. ‘Neepawa’.
Additional index words: Competition, soil seedbank, weed seed yield, wheat plant density, wheat yield, EROCI.
Abbreviations: PAR, photosynthetically active radiation.
