Does wither damage cause -1/-1 counters to persist after combat ends?

Wither is a static ability that modifies how a source deals damage to creatures. Under CR 702.79a, damage dealt by a source with wither is dealt in the form of -1/-1 counters instead of the normal damage marking system. This is a fundamental change to how the damage is represented, not just a temporary effect.

Normally, damage on a creature is removed during the cleanup step at the end of each turn (CR 514.2). However, because wither replaces damage with -1/-1 counters, there is no 'damage' left to remove — only counters. Counters are persistent game objects that stay on a creature indefinitely until something specifically removes them (CR 122.1).

This means a creature that survives a combat hit from a wither source will carry those -1/-1 counters into subsequent turns, reducing its power and toughness permanently unless counters are removed by a spell or ability.

Example: Your opponent's 3/3 creature blocks your 2/2 creature with wither. The 2/2 deals 2 damage as two -1/-1 counters to the 3/3. The 3/3 survives (it has 3 toughness). After combat and the cleanup step, those two -1/-1 counters remain, leaving the 3/3 as a 1/1 for the rest of the game until something removes them.

Note that wither works alongside infect (CR 702.90) in concept, but they are different abilities — infect also places -1/-1 counters on creatures but additionally places poison counters on players, whereas wither only affects creatures with counters and deals normal damage to players.