Need help with a diagnosis!

[Bearclaw]

Hey guys, I really need your help with this one. Client calls me and says that over the last week, leaves on his oak tree started dying and falling off. I think this is Oak Wilt, but I am not sure. I treated the tree with Imidichloprid for aphids about a month ago.

The tree is a Black Oak based on the giant size of the leaves and the bark. The tree is crawling with black ants, and eastern prarie yellow jackets and bald faced hornets are everywhere.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/SAYnjA22XqF_ThMSKsjG6A?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-QrBanQ-XAx8/TjshNBru5QI/AAAAAAAAAJk/VdKsvdNtDkg/s800/IMAG0026.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>
Overall look.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/2b-xD5buwu43w8VkkhB8vg?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-bhJXtdiGHEc/TjsiqTApelI/AAAAAAAAAKM/JOuSAHIvIkU/s800/IMAG0024.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>
Twig death and blackened.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/SNpFYmXriJg8gh4prCu_Cg?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/-I-mjoGeAekU/TjsjQ2iRuPI/AAAAAAAAAKY/9oPLqfngOVI/s800/IMAG0022.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>
Weeping.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/5RYCNGT2yntnuiliOik3jA?feat=embedwebsite"><img src="https://lh5.googleusercontent.com/-at732LwI5fE/TjsjesaXBfI/AAAAAAAAAKc/eFS9JUuFVlM/s800/IMAG0021.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>
Galls, often on the dead twigs, usually at the leaf attachment point.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/J-oXW4cfHSIfmMDnGCYt6Q?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/-FzUwVYJ5kfE/TjsjwyBFkfI/AAAAAAAAAKk/AjzHLp0Img0/s800/IMAG0020.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>
Closeup of the leaf, almost looks like oak mites and powdery mildew.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/zva7Ii8C3OZBQScwyQTIRg?feat=embedwebsite"><img src="https://lh5.googleusercontent.com/-HIlyl1YrDtM/Tjsj4TvQr3I/AAAAAAAAAKs/vS6qd6FtsoU/s800/IMAG0019.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>
Blackened stems with shepards crook, almost looks like fireblight.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/1OqaDvIaGGgFEPMghaKNAg?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-A2hIGsntFD8/TjskAvvEWJI/AAAAAAAAAKw/3nBVcgFIx3c/s800/IMAG0018.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/hYUQXCyXUgVtkoo7iUTMgw?feat=embedwebsite"><img src="https://lh5.googleusercontent.com/-hYu2v39WLdY/TjsjoTuwkdI/AAAAAAAAAKg/kwS4d_SwPQM/s800/IMAG0016.jpg" height="800" width="478" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/mAEEbUFn8bk-ZFVqx-Y_6Q?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/-DcAKKAxpzeE/TjshF8r9P5I/AAAAAAAAAJQ/V3DnZBtliP4/s800/IMAG0028.jpg" height="478" width="800" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/BearclawArborist/Oak?authuser=0&feat=embedwebsite">Oak</a></td></tr></table>
Good leaf stalk, and branch.

 

[woodworkingboy]

Just read where galls can be caused by a certain wasp. Gouty or Horned gall. That does appear like powdery mildew. Been fighting it here during our wet season, so am familiar with it.

 

[sotc]

Excellent photos for diagnosis fwiw but we dont have oak wilt here so couldn't say for sure. I'll try looking it up though

 

[sotc]

Sounds like it other than the book published in 2005 says its not in Colorado yet. The yellow/brown leaf veins are a symptom. Another is to prune off an infected limb and look for brown spots in the cross cut section near the new wood. Also you can peel the limb and look for it. Often dies 6 weeks to 1 year from observable symptoms

 

[NeTree]

In other words... cut it and replant.

 

[Bearclaw]

Crap... I didn't think it was in Colorado yet. I did do a cross section and a peel, and saw the brown circle in the cross section and the stripes in the peel. I'll give it another couple of days to see what everyone else has to say. Thanks Willie.

 

[Bearclaw]

No one else has any input? Guess I'll give the client the bad news.

On a side note, I read that to prevent furthur spread of the disease, I need to wait until the tree is completely dead before I remove it, and furthur that I should trench around the tree at the dripline of the canopy to prevent any possible root spread.

There are no other oak trees on the property or anywhere near the vicinity.

Thoughts?

 

[MasterBlaster]

I need to wait until the tree is completely dead before I remove it

What's the reasoning behind that?

 

[FJR]

No need to trench if there are no other Oak trees on the property.

 

[DMc]

I think this is Oak Wilt, but I am not sure.

I don't think so, but there is no need to guess. You have some great resources close by in the Colorado State University Extension service. www.ext.colostate.edu

Oak Wilt specific clues for diagnosis: leaf discoloration in the red/black oak group is marginal not veinal. Usually part of the leaf stays green. When the leaves do turn brown they fall off. The retention of the leaves is a big diagnostic pointer. Almost all other diseases on oaks cause the leaves to persist. Like your oak.

The oak does appear to be in trouble. So getting a sample into the extension service is the best bet for id.

Just out of curiosity, has this oak been or have access to via the root system nitrogen fertilizer? Oaks break ties with the soil associates and become much more vulnerable when nitrified.

Dave

 

[Bearclaw]

What's the reasoning behind that?

Remove infected trees
Trees that are infected with or have died from oak wilt should be removed and properly treated to prevent development of spore mats. These treatments include debarking, chipping or splitting, and drying the wood. Covering dead wood with plastic, burying the edges for 6 months, and then air-drying for a similar time will kill the fungus and any associated insects. Trees that die in summer should be removed and treated before the following spring, when new spore mats can develop. If the wood is sufficiently dried, however, spore mats will not develop.

A word of caution: Removing a diseased tree that is still living may actually spread the infection by accelerating the movement of the fungus into adjacent trees that are grafted to it by the roots. To avoid this problem, before removing living diseased trees disrupt interconnected roots as described in the section on "Controlling existing infection centers."

Per: http://www.na.fs.fed.us/spfo/pubs/howtos/ht_oakwilt/toc.htm#integrated

Oops, guess I should have read that a little closer.

 

[Bearclaw]

I don't think so, but there is no need to guess. You have some great resources close by in the Colorado State University Extension service. www.ext.colostate.edu

Oak Wilt specific clues for diagnosis: leaf discoloration in the red/black oak group is marginal not veinal. Usually part of the leaf stays green. When the leaves do turn brown they fall off. The retention of the leaves is a big diagnostic pointer. Almost all other diseases on oaks cause the leaves to persist. Like your oak.

The oak does appear to be in trouble. So getting a sample into the extension service is the best bet for id.

Just out of curiosity, has this oak been or have access to via the root system nitrogen fertilizer? Oaks break ties with the soil associates and become much more vulnerable when nitrified.

Dave

Seeking the help of the extension sounds like the best idea, I will call them to see what samples I need to gather.

The oak is planted in a fertilized lawn area, and he did recently fertilize.

 

[Burnham]

DMc is a smart man...knows the biz as well as anyone. Sounds like good advice to me, too.

 

[Bearclaw]

UPDATE! Got it figured out. Man this one really bugged me and took almost 4 hours of research to figure it out.

The problem was Kermes Scale and Botryosphaeria.

Oak Tip Flagging — This summer you may have noticed that many black and pin oak trees had brown leaves at the tips of their branches. Though wilted and browned, the leaves were still attached to the tree. This tip flagging was observed scattered throughout the tree and usually within 12 inches of the tip of a twig.

There were two common causes of this leaf flagging: the fungus Botryosphaeria quercuum and one of several scale insects including Kermes species. Twigs infected with Botryosphaeria quercuum had blackened bark, were cracked and had dark streaks underneath the bark. Damage caused by this fungus typically does not extend more than 6 inches down the twig, and should not cause serious harm to the health of a tree. This problem occurs cyclically, and usually lasts only a year or two.

Several different types of scale insects were found on affected twigs, but the Kermes scale was most common. Female Kermes scales are light-brown and globular. Females are immobile and often clustered near buds of a twig or branch. These scales feed on sap causing a loss of plant vigor and growth,as well as twig dieback. While a heavy infestation may cause young trees to be stunted or deformed, natural enemies are usually plentiful and control is not necessary.

I don't know why I didn't think of scale earlier, it just didn't look like any scale I've seen and was far too big! I think the tree also has Botryosphaeria as evidenced by the blackened sunken bark and the dark streaks under the bark.

There is no treatment for Botryosphaeria, but the Kermes scale can be controlled by Oils, but are targeted by Lady Beatles! I believe the specific Kermes scale is Allokermes galliformis.

( is subspherical with an average diameter of 5 mm. It is pale yellow with minute and evenly speckled
brown dots mottled with grey, and has a polished and smooth appearance. The upper most part of the tergum has about
seven irregular rows of black dots (often connected by an irregular black line) separated by white or pale yellow bands
(Kosztarab 1996). The three uppermost rows are most distinct and constant (Figs. 4-5).

Thank you everyone for all your help! (spec. Dmc, the Colo Extension lead me to scale.) I hope this helps someone in the future.

 

[sotc]

Most excellent

 

[treelooker]

Really good work there Bearclaw! At first glance those round thingies looked like galls to me; pays to look close. Soil issues may indeed be contributory--sell your client some myco and invigoration and mulch maybe. this might be a close enough call to get their attention to the need to care for the bottom half of the tree.




The roots, that is.

Now what was that about remove and replace???