Broomrape Threat to Agriculture

Abstract

The broomrapes are plants that have modified their biology to feed on roots of other plants, emerging above the soil only to flower. There are about 150 broomrape species, most of which infect wild plants in natural habitats without causing economic problems. However, a few of them have adapted to agricultural ecosystems becoming troublesome root parasitic weeds. The most damaging ones are Orobanche cernua, O. crenata, O. cumana, O. minor, Phelipanche aegyptiaca and P. ramosa all of which severely constrain important dicot crops in Africa, Asia, and Europe. They are continuously extending to new areas, showing an ability to evolve thereby enlarging their host ranges, adapting to new areas and overcoming resistances introduced by the breeder. As flowering plants disseminated by seeds, broomrape distribution and management (containment, sanitation, cultural practices, and biological and chemical control) fall under the purview of weed science. However, broomrapes differ from standard weeds as they behave as pathogens that attach to host roots to feed on them. As for any other disease, the host plants might protect themselves by defence mechanisms that can be selected by plant breeders to develop resistant cultivars. In spite of these efforts, rather than being contained, the broomrape threat is increasing, not only extending to new suitable areas but also adapting genetically to infect new crops and to increase virulence.