Winter wheat yield loss in response to Avena fatua competition and effect of reduced herbicide dose rates on seed production of this species

Abstract

Avena fatua is one of the most abundant and competitive grass weed species in cereal cropping systems worldwide. Despite its main occurrence in summer annual cereals, A. fatua is suspected to cause significant yield losses in winter wheat as well. Five yield loss experiments were conducted over the course of five years to investigate the impact of A. fatua on winter wheat yield. Two additional field studies were conducted to assess the efficacy of two ALS-inhibiting herbicides as well as of two ACCase-inhibiting herbicides at variable dose rates on A. fatua seed production. Avena fatua caused significant winter wheat yield losses of up to 40% at densities of approximately 250 plants m−2. Winter wheat yield losses did not differ between years and sites. Relative A. fatua biomass was a better predictor for winter wheat yield loss as A. fatua density and biomass. Three out of four herbicides showed high efficacy against A. fatua, even at reduced dose rates, but A. fatua seed production was not directly related to herbicide efficacy. Seed production was rather influenced by the mode of action and the competitiveness of the winter wheat stand. The results showed that A. fatua can be a serious threat for winter wheat production in the local conditions, leading to high yield losses if not controlled. We did not find a general potential for reducing herbicide dose rates for the control of A. fatua in winter wheat due to variable effects on A. fatua seed production. The potential is highly dependent on the winter wheat competitiveness and herbicide mode of action.