What is significant about the fact that it is Ma who decides when the family should move on?

Pa has become rather impotent in spirit. Regarding Ma Joad's forceful control of the family, Pa remarks that women seem to be in control, and it may be time to get out a stick. Ma hears this, and tells him that she is doing her job as wife, but he certainly isn't doing his job as husband.Ma Joad becomes the only engine which moves this family. This is ironic because it is traditionally the male that serves this function.