The spectral radius of graphs with no K2,t minor

Let t >= 3 and G be a graph of order n, with no K-2,K-t minor. If n > 400t(6), then the spectral radius mu(G) satisfies mu(G) <= t-1/2 +root n+ t(2) -2t - 3/4 , with equality if and only if n 1 (mod t) and G K-1 V left perpendicular n/t right perpendicular K-t. For t = 3 the maximum mu(G) is found exactly for any n > 40000. (C) 2017 Elsevier Inc. All rights reserved.