The apples turn to brown and black,
The tyrant's face is red.
The apples turn brown (rot) and black (burned), as the previously lush, fertile ground is scorched by battle.
This ties back into the Lord Of The Rings references. The steward of Gondor, Denethor, becomes something of a tyrant during the events of The Return Of The King, losing his mind due to events unfolding around him.
Overthrown by Gandalf and facing the loss of his son, he chooses to commit suicide by setting himself ablaze.