Following courses are closed in Wisconsin to my knowledge - some are due to the COVID-19 madness, some had already been pulled due to every year spring thaw / rain / muddy conditions.
UW Parkside (all courses on campus)
Vollrath (Sheboygan)
Kiekhaefer (FDL)
Denoon (Muskego)
Valley View (New Berlin)
Spassland (Germantown)
Sussex Village Park
All 5 main MKE County Parks courses (Dretzka winter & summer/Brown Deer/Estabrook/Dineer/Root River)
Bird's Ruins (Marshall)
Yahara Hills (winter) Hiestand, Vallarta Ast, Capital Springs, Elver (Madison)
McDill Pond, Mead Park, Standing Rocks, Yulga, Big Eau Pleine (Stevens Point area)
Wilderness Campground (Montello)
Rowe Park (Onalaska)
This is no exhaustive list, and I would expect more to follow suit, unfortunately. Please follow state ordered social distancing requirements, and practice "better than you're used to" hygiene if you choose to play a course that's still open. I don't really care one way or the other if you follow the directives of the PDGA, but be smart, be courteous, and don't ruin things for everyone else if you do play. Please STRONGLY consider playing solo rounds only, or if you must, keep your group sizes small and keep your distances from each other.