John Savage wrote:

I believe I've heard Graham Ross (Ch 7) say that the only way to have
any success in getting rid of onion weed is to use an eye dropper and drip
a couple of drops of neat Zero straight down into the crown of the plant so
it runs into the heart and kills all the bulblettes in the cluster. Repeat
this exercise each Spring.

I will bet that he has never actually done this in reality.