How It Works
  • When you register you supply an email address and a password.  Your email address is your username and if you forget your password then you can retrieve it by entering your email address and clicking on the "Email My Password" button.
  • If the email address listed on this site is no longer valid then you should send a note requesting that your email address be changed. Please don't register twice, just let us know your email is no longer valid.
    If you remember your password you can login using the old email address and password, then you could change your email address yourself, otherwise contact us.
  • Click on the "Comment/Question/Report Error" button at the top of the left menu bar to request an email change. 

PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Thursday, September 28, 2023 .  Available Copyright © 1993- 2023 All rights reserved. Fair use of this material is encouraged. Proper citation is requested.