urbpan | 365 Urban Species. #210: Quince Rust

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urbpan. Location: ornamental hawthorn tree on Parkway Road, Brookline.

Urban species #210: Quince rust Gymnosporangium clavipes

"Rusts" are fungi that infect plants, reproducing with galls that often produce orange spores, resembling iron oxide. Many different cultivated plants are infected with rusts, keeping agricultural researchers busy with controls and preventative measures. Quince rust is a close relative to the more well known cedar-apple rust. These fungi have very interesting life cycles, involving alternating host plants. The fungus infects red cedar (Juniperus virginiana), and when mature, produces a gelatinous gall that releases spores that must infect certain trees in the rose family (apple, quince, hawthorn, etc.) in order to continue the life cycle. When the tree fruits, some of the fruit erupt with orange spore-producing projections. The spores from these projections must infect red cedars in order to continue the life cycle, and so on. Fortunately, from the point of view of the fungus, red cedar is a popular choice for urban landscapers, as are many species of hawthorn and flowering crabapple. This organism is hated by ornamental tree nurseries, but is fascinating to the urban nature lover. If not fascinated, one can be amused by tossing the infected fruit onto a hard surface, where it lands with a dramatic puff of spores.

For another gall-producing fungus, see black knot.

Flat | Top-Level Comments Only

Yagh. I'm a fungophile, but a leaf coated with rust can give me the heebie-jeebies. Not sure why.

Maybe it's because of the scifi stories where people get infected by a fungus and end up looking really strange (and under the control of the fungus, of course!;)

The kind that erupt out of the leaves are more disturbing to me for some reason. It makes the plant look more "sick."

I agree with that. Also, for me I think it has something to do with feeling out of control. The spores are so fine, and spread just from bumping the leaf... I'm okay with getting dirty/grubby/dusty, but this sense of something secretly being everywhere, and there's very little I can do about it.

Yar. I agree.

I was just given the heebie jeebies as well. (excellent descriptor of sensation stolen from plantgirl)

A nice plant disease that DOESN'T give the heebie jeebies... and has the best name ever...

SMUT.

One of my favorites, thank you.
Cedar apple rust makes me smile too; I can still remember first discovering it back in college. I find the whole plant cycle and relationship with various trees so fascinating. :)

I have a tree in my front yard that for the first time in the 6 1/2 years I have lived here has the same thing on it as the pictures here. I am worried both for the tree's health and my family's, since I have read that some fungus's affect humans. Should I be concerned about either? The tree seems healthy otherwise. http://www.associatedcontent.com/article/374215/is_cancer_a_fungus_part_ii.html?cat=5

While in some cases certain pathogens have been known to switch from one mammal host to another, or even from birds to humans, there is no case that I am aware of, of a disease jumping from plants to animals.

The fungal diseases that affect animals include ringworm, athlete's foot, and aspergillosis. Some people may have allergies to some fungus spores, especially mold spores. People who are immunosuppressed are more prone to get fungus-borne diseases.

Because fungi are strange to us, they are subject to many suspicions and worries that they don't deserve. I wouldn't worry too much about your tree. The rust doesn't want to kill it--then it wouldn't be able to reproduce. The tree photographed above has had the disease for at least four or five years and otherwise appears healthy, producing full white blossoms and 90% of it' fruit doesn't show the rust.

will this fungus hurt a horse, we have now discovered this fungus in some tree growth that our horses walk through they generally do not eat in this area but do we need to worry about this spreading and our horses eating it

I don't imagine that it would hurt a horse, and I've never encountered this concern in my research. I'd pay attention to them and see if they are even tempted to do so. If they do eat some fruiting bodies, consult your vet about what the risk may be.

Edited 2010-04-25 14:27 (UTC)

365 Urban Species. #210: Quince Rust

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Budding People.....

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This fungus in on my tree!

Re: This fungus in on my tree!

orange fungus with tentacles

Re: orange fungus with tentacles