Coherent control of the vibrational dynamics in crystalline polydiacetylene is demonstrated by tailoring the Stokes pulse of a coherent anti-Stokes Raman scattering (CARS) setup in a feedback-controlled self-learning loop. The feedback signal is derived from the spectral distribution of the CARS signal. Controlled excitation of one mode and simultaneous extinction of all other modes with high efficiency is demonstrated. In addition, the relative phases of the three normal modes have been controlled allowing excitations of local modes and suggesting the possibility of ground state reaction control.