[doctoboggan]

I imagine if the robot is the one who planted the original crops it would know exactly where they should be. Any other growth is defined as a weed.

[claar]

Exactly. You don't even need the robot to plant it; crops are planted in rows. Tractors and combines today already track exactly where the plants are planted down to sub-inch accuracy (http://farmindustrynews.com/accurate-inch -- other source, my family farm).