Monday, April 07, 2008

Cedar-apple rust

cedar apple rust

Extension agents probably hear it a lot this time of year: What the heck is that alien orange thingy in my cedar tree?!

noodly appendages or medusa head?

Check out those gelatinous telial spore horns (noodly appendages).

It's Cedar-apple rust, and it's caused by the fungus Gymnosporangium juniperi-virginianae.

If yours doesn't look quite like this, it might be one of the similar (related) rusts: Cedar-hawthorne rust or Cedar-quince rust. Check the chart of rust differences.

Basically, the Cedar-hawthorne rust's noodly appendages are short and stubby (as opposed to the long and thin ones on the Cedar-apple rust gall shown here). And Cedar-quince rust is mainly just orange goo on bark and twigs. You can see pictures of the latter on my previous posts on the subject here and here. The photos at the first link also show how the rusts appear when they're not quite so wet.

I can't seem to stop writing about these rusts when they make themselves so obvious in the spring. The way they alternate hosts, and of course their appearance, is so unusual.

Fungi expert Tom Volk has written about Gymnosporangium juniperi-virginianae too, in a much more scientific fashion, here.


Jenn said...

"noodly appendages"

Girl, you crack me up. And such a PERFECT description.

*goes off grinning*

pablo said...

With all of the cedars I have at Roundrock, I can't recall ever seeing any rust on them. I don't suppose their are any orchards around to help promote the species.

Rurality said...

Thanks Jenn, I have to admit I didn't make that phrase up myself... I stole it most heinously!

Pablo, you really have to be there at the right time to see them like this. They're not always so day-glo orange. So it's possible you may have them (esp higher up in the trees) and not realize it.

mon@rch said...

Rurality, I just love these photos! how Stunning!

Mad Man Bamboo said...

Wow, at least its a pretty pest....


Rurality said...

Thanks Tom! I think I forgot to say that these two were taken with my husband's camera (the Sony Cyber-Shot). I've been using it more lately since it's so handy to carry around.

Hi Sean, yeah it's funny, I wasn't even thinking about removing them! We have a little crabapple tree not far from the cedars and it does not seem to bee too terribly affected.

CatHerder said...

I have never seen that before...thats pretty cool!

Annie in Austin said...

It was 'noodly appendages' that got to me, too, Rurality - if it were less droopy it could be Sideshow Bob.
There are only a few junipers around my neighborhood and I usually ignore them but now will have to take a look.

Annie at the Transplantable Rose

lisa said...

Very cool....I've only seen the orange goo, not the "octopus". Your posts and pictures are so interesting!

Rurality said...

CatH, yeah as fungi go, it's pretty entertaining!

Annie, oh how could I have forgotten Sideshow Bob?! ;)

Lisa, yup, rather like an octopus. Or spaghetti. :)

anne said...

(chiming in belatedly)

This is one of the primary organisms we study at my lab. We have cedars planted in between the apple trees so that we always have plenty of inoculum around. Man, you should see the galls on the cedars this year! I think we're going to have a bumper crop of cedar-apple rust.

Great photos, all of them (these and your wildflower ones!). I've fallen behind in my blog reading and writing because the semester is drawing to a close and I am swamped. Happy spring to you!

Anonymous said...

do u no if the apple rust is edable