How do I remove crops when blocks under it are destroyed?

So I've finally come up with procedures to make my plants grow up to 3 blocks high. Now I just need to make a procedure that deletes the whole crop if the the block underneath them is destroyed. I did come up with a procedure, but it turns out to be really slow, almost like the tick update procedure is not being called quickly enough. I can destroy the block underneath but then they react maybe 2-3 seconds after? What I did was to run a if/do loop to check whether the block underneath is air, if yes then remove block.

How can I make this as fast as in standard vanilla minecraft?