# white powdery fungus(?) on Post Oaks



## priest (Mar 2, 2007)

A client of mine has a yard full of Post Oaks, many of which have large areas of whitish-gray powder on their trunks. My best guess is that it is a fungus of some kind. Whatever it is has caused the outer bark to disappear. You can pinch off little bits of the stuff and its like powder between your fingers. I didn't have my camera along, but when I go back I'll get some pictures. Any ideas what sort of affliction this is and possible treatments?


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## arborleaf (Mar 5, 2007)

Where on the trunk is the powder located? It sounds like Armillaria fungus, depending where its located.


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## BayouTree (Mar 8, 2007)

*Hypoxylon Canker?*

Could be Hypoxylon Canker. Some pics would deffinately help. Hypoxylon usually infects trees that have been stressed in some way. There is no treatment other than keeping the tree as healthy as possible, mulching the root zone, supplemental watering, etc.


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## underwor (Mar 9, 2007)

Could be smooth patch, white patch, or bark patch caused by _Aleurodiscus oakesii_ on white oaks, of which post is one. Only affects the outer bark layer, leaving the trunk smooth and white. No long term effects outside of looks. The following picture shows a trunk where one part is not infected. It is a white oak, _Quercus alba_. Second photo is more common look for white oaks in southern Illinois. 

http://165.234.175.12/photos/Pathology/smoothbark oak 2.jpg

http://165.234.175.12/photos/Pathology/Smoothbark oak.jpg


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## treeseer (Mar 9, 2007)

i think Bob nailed it, check the pics, very common on Q stellata


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## priest (Mar 10, 2007)

Yep that's it all right. Thanks for your help. Here's some other information I found on the stuff:

"So what's with the unusual name, Aleurodiscus oakesii? "Aleuro-" means flour, referring to the white powdery nature of the surface of the fruiting body, and "discus" refers to its disc-shaped structure. Thus Aleurodiscus means "flour disc." It is widely assumed by both professional and amateur mycologists that the epithet oakesii refers to the host, the oak tree. However, it is actually a pun (intended!) made up by the mycologists who first described the fungus as Corticium oakesii Berk. & Curt. in 1873. [Greveilea 1(11):66]. To the left you can read the original description of the species. However, since all mycological species desriptions must be written in Latin, you may have to brush up on your dead language translation! However, you'll be surprised how much of it you will understand if you know some mycological terminology. The Reverend M.J. Berkeley and M.A. Curtis named the fungus in honor of William Oakes (1799-1848), a famous Botanist from New England who did much of his work in the White Mountains of New Hampshire. Apparently Oakes collected the original sepcimen."


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## underwor (Mar 10, 2007)

I did not know where the name came from. Thanks for the info.


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## treeseer (Mar 11, 2007)

A cool story, one of many in the tree name world. Thanks!


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