Once Christ rules as King on earth, the earth will be restored from the curse that came to be when man first sinned (see Genesis 3).
There will be no pest or weeds. Even the animals will return to their original state and predators will become herbivores. There won’t be disease either. Earth will be very close to a paradise, but sin will still exist.
“The wolf and the lamb shall feed together, and the lion shall eat straw like the bullock: and dust shall be the serpent’s meat. They shall not hurt nor destroy in all my holy mountain, saith the LORD.”
ISAIAH 65:25 (KJV, HOLY BIBLE)