Oh, is it? I just read about how it causes roots to rot when applied to existing plants instead of prior to planting

I ma guessing you will be ok, if you are worried clear it off. Garlic seems really tough to me and I have composted with pine needles and straw with no issues at all.

In general, manure application can promote pathogenic fungi, but if not overwatered, the risk is small. Uncomposted manure can lead to root rot from ammonium toxicity. Composted manure is a lot safer.

I wouldn't give it a thought.

I wouldn't worry about it either. If it was just raw manure you wouldn't want to put it fresh into your garden. But composted it's great. And so long as you aren't burying your garlic in anything and just dressing your garlic- or in this case a wee bit of spillover- you shouldn't have to worry about any rotting issues.

Black Kow is a hot composted product made from cow manure. Since they make sure they are above 140- usually getting around 150 during the composting, that effectivly kills/burns off most of the ick. They regularly turn their rows during the process to make sure everything gets done. Since it's a product intended for directly using in your veggie garden, it's not likely to cause nute or other burns that can happen sometimes with uncomposted manure or fertilizers meant to water in/break down before planting.