We report measurements of the exclusive cross section for e^+e^- →D^0D^-π^+ over the center-of-mass energy range 4.0 GeV to 5.0 GeV with initial-state radiation and the first observation of the decay Ψ(4415)→D^0D^-π^+. From a study of the resonant substructure in Ψ(4415) decay we conclude that the Ψ(4415)→D^0D^-π^+ decay is dominated by Ψ(4415)→D\bar{D}_2^*(2460). We obtain B(Ψ(4415)→D^0D^-π^+_nonresonant)/ B(Ψ(4415)→D\bar{D}_2^*(2460)→D^0D^-π^+)<0.22 at 90% C.L. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 fb^{-1}.journal articl
