Hand saws make the cuts loppers cannot - thick branches, roots, and jobsite materials. Folding pruning saws like the RazorTOOTH use aggressive teeth for fast cuts in green wood and fold closed for safe carry; rigid pruning and hack saws give more control on bigger work.
For irrigation work you will also find PVC hand saws and hacksaw frames here for cutting pipe and metal. Choose blade length for the diameter you cut, and a folding design if the saw rides in a tool bag. For clean, square pipe cuts, a dedicated PVC cutter is faster.