  Many of the hadron-hadron cross sections required for the study of the
dynamics of matter produced in relativistic heavy-ion collisions can be
calculated using the quark-interchange model. Here we evaluate the low-energy
dissociation cross sections of $J/\psi$, $\psi'$, $\chi$, $\Upsilon$, and
$\Upsilon'$ in collision with $\pi$, $\rho$, and $K$, which are important for
the interpretation of heavy-quarkonium suppression as a signature for the quark
gluon plasma. These comover dissociation processes also contribute to
heavy-quarkonium suppression, and must be understood and incorporated in
simulations of heavy-ion collisions before QGP formation can be established
through this signature.
