servant of the scale during a board wipe
All creatures die at the same time from a board wipe, and you could not resolve any abilities while the board wipe is resolving.
Servant of the Scale triggers as it dies, but the ability only enters the stack after the board wipe has finished resolving.

603.3. Once an ability has triggered, its controller puts it on the stack as an object that’s not a card the next time a player would receive priority.

The active player gets priority (the right to cast spells and activate abilities) after a spell has resolved:

117.3b The active player receives priority after a spell or ability (other than a mana ability) resolves.

By that time, all creatures have already died.
Also, you could not activate Fertilid's ability during the board wipe, for the same reason you don't get the Servant trigger during the board wipe's resolution, because you need priority to do that.