How significant a threat do you view agroterrorism as broader subset of biological terrorism?

How significant a threat do you view agroterrorism as broader subset of biological terrorism? Where in the food chain is this attack most likely to occur?

Resource:
http://ezproxy.apus.edu/login?url=https://search.proquest.com/docview/921992777/
https://www.ecronicon.com/ecag/agriculture-ECAG-01-000021.php
https://www.rand.org/pubs/testimonies/CT213.html