Most parasitic plants do not form mycorrhizal associations, so direct interactions between them and arbuscular mycorrhizal (AM) fungi have rarely been studied. Using a facultative root hemiparasite, Pedicularis tricolor, with a potential to form AM associations, Li et al. show that inoculation with two AM fungi (Glomus spp.) strongly suppresses the initiation of haustoria, the parasite-specific structures responsible for host attachment and nutrient transfer. This first demonstration of a significant effect of AM fungi on haustorium initiation has potential for future development of biocontrol strategies in management of parasitic weeds.