The effect of a graft transformation on distance spectral radius

We study the effect of a graft transformation on the distance spectral radius of connected graphs. As applications, we determine the unique n-vertex non-starlike tree with maximal distance spectral radius, and the unique n-vertex non-caterpillar trees with minimal and maximal distance spectral radii, and we also consider the distance spectral radius of non-starlike non-caterpillar trees.