  We study a ferromagnetic Heisenberg spin system on the square lattice, with
nearest neighbors interaction J_1 frustrated by second J_2 and third J_3
neighbors antiferromagnetic interactions, using a mean field theory for the
Schwinger boson representation of spins. For J_3=0 we find that the boundary
between the ferromagnetic and the collinear classical phases shifts to smaller
values of J_2 when quantum fluctuations are included. Along the line J_2/|J_1|=
1 the boundaries between the collinear and incommensurate regions are strongly
shifted to larger values with respect to the classical case. We do not find
clear evidence for spin gapped phases within the present approximation.
