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Most plant viruses and systemic posttranscriptional gene silencing (PTGS) signals are normally excluded from the shoot apex. Ectopic expression of a potexvirus movement protein (TGBp1) in the apex of Nicotiana benthamiana resulted in a profound change in plant development. In the most extreme conditions, plants developed radially symmetric organs and were named "spikey." Foster et al. (pages 1497-1508) describe these plants and the reestablishment of organ polarity through the activation of PTGS. Here, in contrast to control plant lines, both virus and the silencing signal were shown to penetrate the shoot apex. These results provide proof of concept for the operation of a zone of surveillance regulating RNA trafficking that protects the shoot apex, and consequently reproductive tissues, from viral invasion. The evolution of such a system is consistent with recent observations of phloem mobile RNA species being delivered to the apex and a potential role for this surveillance system in regulating plant development.