shrivel up vs die down

shrivel up and die down both are verbs.

Word	Noun	Adjective	Verb	Adverb
shrivel up	No	No	Yes	No
die down	No	No	Yes	No

As verbs, die down is a hyponym of shrivel up; that is, die down is a word with a more specific, narrower meaning than shrivel up:

Other hyponyms of shrivel up include atrophy, blast, die back, dry up, mummify.

shrivel up (verb)	die down (verb)
wither, as with a loss of moisture	suffer from a disease that kills shoots
	become progressively weaker