Control of Conyza spp. with Glyphosate – A Review of the Situation in Europe
Conyza bonariensis (L.) Cronquist, Conyza canadensis (L.) Cronquist, Conyza sumatrensis (Retz.) E. H. Walker, resistance, weed management
In Europe, glyphosate resistant populations have developed in some weed species in perennial crops, including three species of the genus Conyza documented by the International Survey of Herbicide Resistant Weeds. Conyza spp. biology is reviewed in this paper and related to population dynamics and the development of resistant populations. Suboptimal growth stage at application, improper agricultural practices such as overreliance on glyphosate and long-term use of sublethal doses are identified as the most important factors of resistance development. Current control methods in perennial crops including mixtures of glyphosate with other active ingredients are discussed and effective weed management strategies are described to manage the development and spread of glyphosate resistant Conyza spp. in Europe.