Energy transfer in RbMnF3 was studied by time-resolved spectroscopy of 4T1g exciton and trap luminescence. Uniaxial stress was used to lift the orientational degeneracy of the Jahn-Teller distorted MnF6 octahedra. Stress also reduces the excitonic transfer rates considerably. The most drastic reduction of transfer and a nonexponential decay was observed with (110) stress. Evidence for two-dimensional transfer under (110) stress is given by computer simulation of random-walk processes and by a calculation of nearest-neighbour transfer integrals.