Everything that I've found says that biocontrols are still being tested in Michigan and are not currently available to the public. I found records that at least 5 have been studied for about the last 10 years. Most of the testing has been done in areas that are being managed with livestock, i.e. controlled pasture trials. 

I would recommend connecting with someone at your local Cooperative Invasive Species Management Area (CISMA) to see what resources they could provide. Yours is the CAKE CISMA: https://www.cakecisma.org/

<personal data hidden> ext. 5 - main number

Treatment/Management Inquiries

Wade Foster, Restoration Crew Lead

<personal data hidden>

Other resources for management:

https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5410116.pdf

https://www.canr.msu.edu/news/spotted_knapweed_in_dairy_pastures_and_hay_fields

https://www.misin.msu.edu/facts/detail/?id=35