# hypoxylon canker in post oak and blackjack



## priest (Sep 17, 2007)

A situation has arisen from a new client outside of town who needs help because much of his 11 acre wooded lot is being badly damaged by Hypoxylon canker. He said that his Blackjacks (which represent about 15 percent of the tree population) first started becoming symptomatic and dying about five years ago. The infection spread slowly to other blackjacks around his house and driveway. 
Perhaps due to the severe drought of 2005-2006, the canker began to spread to and kill Post Oaks (which represent about 70 percent of the trees) in growing patches of forest near previously infected Blackjacks. 
This season we had a very harsh late freeze in April that severely affected the Post Oaks. Many did not re-leaf out until May or even June. And, following that setback, the canker has spread enormously among the Post Oaks and Blackjacks on this property.
In the worst 3 acres or so around the house, every tree shows stress (thin foliage, partially or totally brown leaves, etc.). Many of the trees have leaves that are half brown, half green. (I will get some pictures soon.) Some of the Post Oaks have already died completely and did not leaf out this year.
The client wants to have the dead trees removed to prevent the continued spread. Of course, with so many trees showing symptoms, I wonder how much preventative impact will be realized. I surveyed the entire area (through horrendous ticks, chiggers, flies, and briars) and marked all trees that show less than half of the foliage healthy. 
Has anyone battled this sort of problem on this scale and have some insight into which trees to remove, which to leave alone, which may recover, which trees are likely to infect others and when? 
I have researched the canker and its life cycle and have read that once the bark falls off, exposing the fruiting bodies, spores are released, affecting new trees. The bark has fallen of the Blackjacks in patches, but it has not fallen off of the dead Post Oaks. So are there still spores being released? And if we have more normal weather in the coming years, what are the chances of recovery?
Thank you for any knowledge you are able to share.


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## priest (Sep 18, 2007)

*record rainfall*

I neglected to mention previously the perhaps very significant fact that after the long drought and late, hard freeze, we received rainfall that shattered all records. We have now had about 56 inches of rainfall this year. The average yearly precipitation is 32 inches. Absolutely extreme weather for the trees.


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## Urban Forester (Sep 18, 2007)

Hypoxylon canker is one of the diffuse cankers (i.e. Chestnut Blight) it produces ascospores AND conidia, which makes it a very fast mover. Chemical control is has not been shown to be effective. As a 'secondary' pest relieving stress and maintaing health is mostly the recommended course of action. Removal and pruning are also used. See this PDF for more info:

www.forestry.state.ar.us/manage/hypoxylon.pdf


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## treeseer (Sep 20, 2007)

that info looks solid, but here I see no preference for reds; white oaks get it more because we have more of them.

someone emailed me pics of hypoxylon thinking it was oak wilt. i responded it was a tree by tree decision; with 11 acres it must be rough to manage.


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## Dixie1 (Sep 20, 2007)

info from your area. http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2312/F-7620web.pdf


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## treeseer (Sep 21, 2007)

the AR info is much better.


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## treeseer (Sep 21, 2007)

So Dan on firewood is hypoxylon beneficial because it speeds drying?

maybe, but i'M NOT SURE ABOUT THE HEALTH impact of huffin all those spores.


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## priest (Sep 21, 2007)

Thanks for the responses. And along the lines of firewood . . . maybe not the best idea to distribute it around when it's infested? Yeah, it's supposed to be burned, but maybe not right away, if at all. 
Some of the literature out there makes it seem like hypoxylan is omnipresent anyway, just not lethal until the tree is weakened, and some other reports make it seem to be more localized, in which case we should take more precautions. Who knows?


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