It mentions in the end in the footnotes you can mix together high vomitoxin and low vomitoxin wheat to produce the needed amount.

  I'm kidding. My dog is gluten-free. Also if you buy 
  the high-vomitoxin wheat you can blend it with 
  low-vomitoxin wheat until you get the perfect amount 
  of vomitoxin. Appetizing, no?