The easy answer is that I never put a penny in my pocket from “big ag” and they never sponsored my research or students. I was reimbursed for travel once when they asked me to talk to some farmers that had questions. All of that is clearly disclosed, and shows that I do a lot of work with no personal remuneration. That’s my job as a Land Grant scientist.
One time they provided funds for my university to support my outreach program. My program teaches scientists, students, postdocs and others how to speak effectively with a concerned public. I was grateful for company support, as it allowed me to (potentially) buy USB drives to distribute scientific literature and presentation templates. It also allowed me to stay a night in a (cheap) hotel and get to the workshop site. I usually put out sandwiches, coffee and pastries too. It is three hours of listening and interacting, so it is the least I can do.
The news of Monsanto support for that educational program made people go bananas. Sadly, it brought me mountains of hate email and complete smear in social media. My 30 years of public science were being maligned by people that saw support of a communications workshop to be high evidence of corporate collusion. That just was not true. Because of the backlash, my institution donated the funds elsewhere and they were never used for outreach. My workshops are now sponsored 100 percent by my own personal contributions and the support of total strangers that donate to spread science education.
And at this point I've heard no company will support my outreach. I heard through the grapevine that "Folta's more valuable if he's completely independent." That's sad. It shifts the burden of science education expense to the public, when companies could be paying for it.
To conclude, no company could ever buy my words, or silence me if there was hard evidence of wrongdoing. There is no amount of money that could ever do that. I'd be the first to speak out. That's clear from the over 11,000 pages of emails that have been freely provided to activists that everything is above board, fully disclosed, and as transparent as can be.