In this paper, I present a case study in the field of crop protection and discuss its epistemological implications. Through the advent of a novel class of objects at the end of the 1970s in Europe and the USA, namely plant elicitors that trigger the plant's own defence reactions, we witness how dissent between epistemic communities appears where assimilation had been the rule. The convergence between the industry and the academia as a coherent " phytosanitary universe " , despite the fact that they are made of several epistemic communities, is put to the test by plant elicitors, which do not fit exactly within existing categories. The plasticity of plant elicitors who can serve both as epistemic things and technical objects (Rheinberger 1997) does not suffice to qualify them as boundary objects bridging diverging communities. In particular, the specific arrangement of epistemic communities that they reveal can be described as Matryoshka dolls. This empirical account provides a fresh look at the relation between physical objects and epistemic boundaries, as well as the configuration of epistemic communities.