Question
Is it necessary to pick the rotten apples from the orchard after the harvest.

Answer
Vikek:
If it is practical and feasible, yes. This is a great way to minimize plant diseases that may be present, especially on the fruit that remains on the ground or rotten fruit on the tree. Many fungal disease microorganisms can overwinter/oversummer on this fruit on and off the tree, then infect the tree next season.  If you can do it, bury or burn all of this rotted fruit.

Steve