Cedar quince rust

Yesterday it rained, which was greatly needed to take some of the yellow out of the air. The pollen has been off the charts. I took my car to the car wash and a few hours later it was dusty yellow again. But another effect of the cool, wet conditions was the fruiting of this fungus on our small juniper trees. At least I think they're junipers, definitely Cupressaceae. Yesterday the fruitings of this fungus looked slimy, like this...
and this...

But today, they've dried up and look more like this...
And this...
What is this strange orange ooze? Spoiler alert! It's in the title of this post. Cedar quince rust is in the same genus of rusts as apple cedar rust, Gymnosporangium. And like G. juniperi-virginianae and most species in the genus they are heteroecious (requiring two hosts to complete the life cycle) and demicyclic (lacking a uredinial stage). The hosts are in the Cupressaceae and Rosaceae. But clearly this is not cedar-apple rust. The telia of G. juniperi-virginianae are formed out of gall-like growths on the stems. When conditions are right, the telial horns project out of orifices, kind of like the eyes and ears of a stress-doll.

THAT up there is cedar apple rust

Cedar-quince rust, on the other hand, isn't associated with complex galls like cedar-apple rust, though it may cause branch swellings and flaky bark. It's the most important Gymnosporangium rust on the rosaceous hosts, quinces and others, according to Sinclair et al. I can't seem to find my newer version right now, oh wait, there it is! The causal fungus is G. clavipes, and it infects far more than just quince, including more than 480 rosaceous species in 11 genera (again, according to Sinclair and Lyon)! As you can see from the photos above, the smaller juniper branches are killed by the fungus, though the basal infections don't appear to be killing the tree in any hurry.

I just went out to check on my cedar apple rust gall on the juniper in my front yard, and it's gone! I thought I'd see if it fruited after yesterday's rain, but it's no longer there. I guess I never posted pictures of it either. They were a little blurry. But I do see some more small infections of G. clavipes on the big tree in the front yard. And here's a link to an even better photo of a G. clavipes infection, as well.