  The fusion number of a ribbon knot is the minimal number of 1-handles needed
to construct a ribbon disk. The strong homotopy fusion number of a ribbon knot
is the minimal number of 2-handles in a handle decomposition of a ribbon disk
complement. We demonstrate that these invariants behave completely differently
under cabling by showing that the (p,1)-cable of any ribbon knot with fusion
number one has strong homotopy fusion number one and fusion number p. Our main
tools are Juh\'asz-Miller-Zemke's bound on fusion number coming from the
torsion order of knot Floer homology and Hanselman-Watson's cabling formula for
immersed curves.
