There is a sample that ships with UltraListView, 'WinListView DragDrop', which demonstrates this concept for the WinListView control. The sample was specifically designed to be easily adapted for use with other Infragistics controls, so modifying it to work with UltraTree should not be difficult (if you have any problems doing so post to this forum and we will try to help).

Note that the image displayed during a drag operation for this sample is generated by drawing UIElements onto a Graphics object; for your purposes, this step would be unnecessary, so you would want to short circuit that aspect of it and just supply the image to be drawn. If you search the source for "private void CreateDragImage", you will find the place to do this (remove the code therein and set the 'this._dragImage' member directly).