  The possibility of Fast Radio Burst (FRB) emission being suppressed at low
frequencies, resulting in a cutoff of the average rest-frame spectrum, has been
raised as an explanation for the lack of detections at meter wavelengths. We
examine propagation effects that could cause this suppression, and find that a
low-frequency spectral cutoff may be generic regardless of the specific FRB
emission mechanism. We then illustrate the effects of a low-frequency spectral
cutoff on the statistics of FRBs, given a cosmological source population. The
observed FRB rate peaks at a specific frequency under a variety of assumptions.
Observations at lower frequencies are more sensitive to high-redshift events
than observations above the maximal-rate frequency, and therefore result in
more sharply broken fluence distributions. Our results suggest that the absence
of low-frequency FRBs, and the differences between the Parkes and the
Australian Square Kilometre Array (ASKAP) FRB samples, can be fully explained
by suppressed low-frequency FRB emission.
