If I disavow website.tld in Google Webmaster Tools because I have a toxic link coming from it, am I also disavowing links from their sub domains too including blog.website.tld?

I guess I could list both the domain and sub domain but I see our link coming up in the sidebar of the main site plus ALL sub domains and I don't want to list all of the sub domains in the disavow (the list is rather LARGE). Is just listing website.tld a simple fix?