  Precise new data for the reaction $K^- p \to \pi^0 \Lambda$ are presented in
the c.m. energy range 1565 to 1600 MeV. Our analysis of these data sheds new
light on claims for the $\Sigma(1580){3/2}^-$ resonance, which (if it exists
with the specified quantum numbers) must be an exotic baryon because of its
very low mass. Our results show no evidence for this state.
