I have rust on my personal yard right now. Showed up about a week ago after it was real warm, rained for a couple days, then every morning real heavy amounts of dew for about a week. Real cool at night warm during the day. I have never had rust show on my lawn before. Conditions just right for it, I guess.
I even have it on 20 rolls of sod I put down last month where I took out a tree for my driveway expansion.
I have it at two accounts that I have never seen rust on in the five years I have done them both.
I do not know if the fall fert I just did will kick it all out or not? Hope so!