Estimated effects of cornflower presence on winter wheat

Cornflower (Cyanus segetum Hill) used to be very frequent and abundant in winter wheat a few decades ago, but because of agricultural intensification it is now an insignificant weed, even classified as endangered in Western Europe. However, cornflower produces nectar that is a resource for pollinators and crop pest predators and parasitoids. To gain benefit from this resource, it is necessary to manage the presence of cornflowers and to maintain the population at a balance that ensures the beneficial ecosystem services whilst avoiding competition with the arable crops. This paper describes bispecific competition trials between cornflower and winter wheat in small experimental plots. The annual experimental conditions were highly variable, leading to plant densities that were too high or too low to estimate a competition threshold. The results provided relevant information on intraspecific competition among cornflower plants and its effect on the growth, the biomass and the yield of wheat. Conventional and organic farming could gain from growing some weeds like cornflower in the fields to provide ecosystem services for the crops.