The translocation of herbicide from bean (Viciafaba) to broomrape (Orobanche crenata)

Application of ¹⁴C-labelled 2,4-D to bean plants parasitized by broomrape led to a concentration of the herbicide in the immature parasite that was up to fourteen times that in the bean root. Not all substances are translocated in this way. ²²Na in sodium chloride was not moved in significant amounts away from the site of application, but sucrose was found to be translocated to the parasite. Application of 2,4-D,2,4,5-T, N.A.A. and D.N.P. to mature Orobanche under field conditions had little effect. 2,4-D is not considered a suitable herbicide for the control of Orobanche in bean crops because of the high sensitivity of the host of this compound. It is thought, however, that the application to the host of a systemic herbicide which becomes concentrated in the parasite to a toxic level could well be an efficient way of controlling this type of parasite.