Topology of codimension-one foliations of nonnegative curvature. II

We prove that a 3-connected closed manifold $M$ of dimension $n\geqslant 5$ does not admit a codimension-one $C^2$-foliation of nonnegative curvature. In particular, this gives a complete answer to a question of Stuck on the existence of codimension-one foliations of nonnegative curvature on spheres. We also consider codimension-one $C^2$-foliations of nonnegative Ricci curvature on a closed manifold $M$ with leaves having finitely generated fundamental group, and show that such a foliation is flat if and only if $M$ is a $K(\pi,1)$-manifold.
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