  Let k, p, q be positive integers with k < p < q+1. We prove that the maximum
spectral radius of a simple bipartite graph obtained from the complete
bipartite graph Kp,q of bipartition orders p and q by deleting k edges is
attained when the deleting edges are all incident on a common vertex which is
located in the partite set of order q. Our method is based on new sharp upper
bounds on the spectral radius of bipartite graphs in terms of their degree
sequences.
