  We argue that the correct definition of the electric current in the chiral
kinetic theory for Weyl materials should include the Chern-Simons contribution
that makes the theory consistent with the local conservation of the electric
charge in electromagnetic and strain-induced pseudoelectromagnetic fields. By
making use of such a kinetic theory, we study the plasma frequencies of
collective modes in Weyl materials in constant magnetic and pseudomagnetic
fields, taking into account the effects of dynamical electromagnetism. We show
that the collective modes are chiral plasmons. While the plasma frequency of
the longitudinal collective mode coincides with the Langmuir one, this mode is
unusual because it is characterized not only by oscillations of the electric
current density, but also by oscillations of the chiral current density. The
latter are triggered by a dynamical version of the chiral electric separation
effect. We also find that the plasma frequencies of the transverse modes split
up in a magnetic field. This finding suggests an efficient means of extracting
the chiral shift parameter from the measurement of the plasma frequencies in
Weyl materials.
