Abstract The reactions π +p→ π o Δ ++, π +p→ ηΔ ++ and K +p→K o Δ ++ are analyzed in a ρ + R Regge-pole model. Kinematical singularities and threshold (pseudothreshold) conditions are incorporated in the parametrization. The polarization data are examined and their implications with respect to the dynamical structure of the helicity amplitudes are inferred. SU(3) symmetry and exchange degeneracy are applied in order to minimize the number of free parameters. A satisfactory description of these isobar production processes is obtained.