  We study out-of-equilibrium dynamics of intense non-abelian gauge fields.
Generalizing the well-known Nielsen-Olesen instabilities for constant initial
color-magnetic fields, we investigate the impact of temporal modulations and
fluctuations in the initial conditions. This leads to a remarkable coexistence
of the original Nielsen-Olesen instability and the subdominant phenomenon of
parametric resonance. Taking into account that the fields may be correlated
only over a limited transverse size, we model characteristic aspects of the
dynamics of color flux tubes relevant in the context of heavy-ion collisions.
