# Bacterial Leaf Scorch?



## appalachianarbo (Oct 2, 2008)

I visited a property today to bid on some crown cleaning in a large oak. There are a few dead limbs (one large - 10" DBH). Several live limbs around this large dead limb have discolored leaves (see pictures). I'm guessing BLS, but they don't have the yellow band between the dead and live tissue. I'll be getting samples to send to the lab next week during the deadwooding. 

Sorry, but I didn't have a camera during the bid, but I'll get some crown shots next week.

What do you think?


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## Urban Forester (Oct 3, 2008)

I'd have some woody tissue cultured also. While you may be right w/BLS, it could also be Oak Wilt. The inward expansion of the scorch is a symptom of both.


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## appalachianarbo (Oct 5, 2008)

> I'd have some woody tissue cultured also.



Yup. I'll be getting some on Tuesday to send off. 

I also have a cryptomeria sample to send to test for cercospora or phomopsis or something like that - tip yellowing turning into dieback extending towards the trunk in random spots around the entire trunk.


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## S Mc (Oct 6, 2008)

Please keep us posted on your findings. I also hope you post more pictures. I use these types of scenarios to increase and expand my knowledge so appreciate sharing.

For instance, neither BLS nor OW popped into my mind immediately on the leaf samples; so will be interested to see what they test out as.

The cryptomeria also sounds interesting. It sounds like cercospora could be more wide spread throughout the plant (starting at the base and working up) and is potentially lethal. Evidently needing no predisposing factor other than fungal activity in the vicinity. The phomopsis canker may be more localized to dieback specific to the area with the canker. Wounded tree more susceptible.

Were both of these issues on the same property? If so, has anything new gone on (last 5 years)? Such as construction, landscaping, new irrigation system, etc.

Thanks for sharing! Keep us posted.

Sylvia


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## appalachianarbo (Oct 23, 2008)

The sample tested positive for BLS. I'll most likely start on OTC and maybe cambistat depending on the owner's objectives.

The lab couldn't find a pathogen in the tissue of the cryptomeria. They said they have received some samples with the same symptoms. I just sent off a root sample, so maybe they'll find something there. It seems to me to be more than cultural.

The trees are on different properties, and no disturbance has taken place on either site. Both trees are in somewhat compacted clay soils.


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## S Mc (Oct 23, 2008)

Personally, I feel all diseases should be required to demonstrate classic symptoms as pictured in our reference material.  

I guess that's what keeps us on our toes, eh? 

The US National Arboretum states in a report dated 7/13/08 that BLS still has no effective preventative treatment. But suggests management to maximize its lifespan much as you stated: pruning out deadwood, improving its environment (such as mulching and appropriate irrigation). They do state that oxytetracycline has been tested and that it caused a remission of symptoms not a cure. But that sounds like it could buy some time for a specimen tree. However, these are trunk injections (per their material) and need to be applied annually.

Are there any other side effects to the OTC? (Hmmmm, need to google...)

Cambistat is an intriguing treatment in that it redirects more of the tree's resources towards root development and enhanced defence. However, application rates appear to be tricky.

I hope you keep us posted on your treatment options and findings. Thanks.

Sylvia


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## appalachianarbo (Oct 23, 2008)

After thinking about it and seeing results from both chemicals, I might try just cambistat. No wounding, and from anectodal evidence, it sounds like it might do a better job. Also, cambistat claims up to 3 year suppression, as opposed to OTC's one year.

I'd be interested in hearing from those who've tried either, or both.


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## Ed Roland (Oct 24, 2008)

S Mc said:


> Personally, I feel all diseases should be required to demonstrate classic symptoms as pictured in our reference material.
> 
> I guess that's what keeps us on our toes, eh?
> 
> Sylvia



*Like a midget in the restroom*  



S Mc said:


> Cambistat is an intriguing treatment in that it redirects more of the tree's resources towards root development and enhanced defence. However, application rates appear to be tricky.
> 
> I hope you keep us posted on your treatment options and findings. Thanks.
> 
> Sylvia



Sylvia, as you know, I've a unique source of information for some of these chemicals. Im told OTC is, basically, the same anti-biotic prescribed to humans with an extra h2o molecule attached. 

Cambistat:
"Paclobutrazol is a synthetic triazole fungicide with more value as a plant-growth regulator (PGR). You’re probably more familiar with its sibling fungicides such as propiconazole, myclobutanil, triadimefon, or miconazole (ok, maybe not mi-onazole, which controls athlete’s foot). As a plant-growth regulator, paclobutrazol is sold under many names, including Profile (Dow), Cambistat (Rainbow Tree Care), Turf Enhancer (Andersons), and Trimmit (Syngenta). It can be applied to a range of trees and shrubs as a basal soil drench or soil injection and is also available for the turf market."

http://hyg.aces.uiuc.edu/secure/subscribers/200317b.html

Interesting that a fungicide treats a bacterial issue...

"Preliminary treatments with paclobutrazol were performed by Bruce Freadrich with the Bartlett Tree Research Lab in Charlotte, NC on red oaks and sycamores. With limited replications, Bruce found a three year reduction in scorch symptoms on treated red oaks, but similar effects were not seen on sycamores. This data has prompted further inquiry, and Rainbow, Bartlett, and the New Jersey Forest Service are collaborating on a much larger field trial with red and pin oaks. In addition, Dr John Hartman at the University of Kentucky is investigating the effects of Cambistat on Bacterial Leaf Scorch in Kentucky."

http://www.rainbowscivance.com/cambistat/cam_enhance_defenses_b.asp

"at least one researcher (B. Fraedrich, Bartlett Tree Research Laboratories) has observed a reduction in bacterial leaf scorch of red oaks."

http://hyg.aces.uiuc.edu/secure/subscribers/200317b.html

I'm not sure I'm ready to introduce growth regulators to control BLS in any other specie without more information. Sure its one more technique to bill for but is it really best practice? Some will argue compellingly: “The effect of paclobutrazol on bacteria is unknown at this time but may be due to increased resistance of trees to infection by bacteria through alteration in leaf surface structure or even the size of stomatal pores.” 
William Chaney (professor of tree physiology, Purdue University)

BUT, Does it work across the board on approximately 12 other species of oak, Sycamore, American elm, Maples: Red maple, Sugar maple, Mulberry, Sweetgum, Almond? 

This is very interesting and I hope this thread continues.
opcorn:


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## S Mc (Oct 24, 2008)

Appalachinardo, how old is this oak tree? What is it's cultural environment? Can you get pictures? Is compaction an issue? Is this tree in a lawn setting? These questions are simply to further my knowledge and education, mind you, so appreciate any further additional comments you may have.

As I read more on this subject it seems to keep coming back to the basic advice of "best cultural practices". BLS can be transmitted through root grafting so if there are any other trees in this area that might be affected, it would be wise to make sure their environment is optimized; mulching and proper irrigation.

Thanks much.

Woodweasel, I was SO disappointed to find out Cambistat is a fungicide! But then fertilizers are "salts" in a way, so this could come back to a little of something is ok, but a lot is dangerous? More googling....... And evidently there are other PGRs out there....lots more googling.

Sylvia


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## Urban Forester (Oct 24, 2008)

I've cambistated about 200 trees in the last 5 years (or so) and one thing to keep in mind, if you don't keep the tree on a 3 year cycle resurgent new growth is incredible. Stem elongation can be twice what it was prior to regulation. Using it to suppress BLS scares the hell out of me, unless the client was willing (to pay) to keep the tree regulated for an extended period.


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## appalachianarbo (Oct 24, 2008)

Sylvia,

The tree is 100+ years, ~45" DBH. It is in a residential yard, somewhat compacted clay, sparse grass growth, slight slope towards the road. Good trunk taper, no basal decay evident, full dark green crown with the exception of the ~15% BLS symptoms. 

UF,

Any chance you can "wean" a tree off PBZ over a few year period? And since PBZ won't cure BLS, the tree will likely continue to decline and possibly die, so sprouting shouldn't be too big of an issue when compared with the loss of the tree. 

I'm wondering how long PBZ has staved off a BLS infection. Any anecdotal evidence out there?

I wonder what people would vote for - PBZ only, PBZ + OTC, or OTC only?


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## S Mc (Oct 25, 2008)

Urban Forester said:


> Using it to suppress BLS scares the hell out of me, unless the client was willing (to pay) to keep the tree regulated for an extended period.



Why would this be a problem? 

As there is no cure, I personally, would prefer to go with cultural management of improving the tree's environment, mitigating stressors to allow it to fight this disease itself. But that is my general philosophy towards most issues as a healthy tree can fight off a lot of problems. However, I am curious as to why the referenced treatment would scare you.

App, this pin oak is reaching it's golden years, at least according to forest service information I have read. It sounds like a wonderful tree well worth maintaining for as long as possible. Remember mulching may assist in the compaction issue besides adding nutrients in an appropriate manner (along with all the many other positive benefits of mulch in general). Good luck in your efforts and keep us posted.

Sylvia


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## Urban Forester (Oct 26, 2008)

S Mc said:


> Why would this be a problem?
> Sylvia



We believe that tree hoppers are one of the main vectors for infection of BLS. Therefore anything that would increase the succulent new growth (working on the assumption that this tree wouldn't be regulated over along period of time.) could increase their activity. I would try tetracycaline alone for suppression and try to increase vigor of the tree.

Paclobutrazol inhibits one single element of the gibberilic chain. When levels drop the chain becomes "active" again. There is no "weaning" that I'm aware of. Those levels need to be maintained to keep the chain "broken".


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## treeseer (Oct 27, 2008)

big dif tween fungistatic and fungicidal.

this is from a 2004 article on bacterial infection in trunks, fwiw

According to research (by Chaney) cited in Tree Growth Retardants in the March 2003 issue of Tree Care Industry, growth regulators have demonstrated a fungistatic property due to the inhibition of steroid production. Since steroids are essential constituents of membranes in both fungi and bacteria, application of growth regulators may also be bacteriostatic. They seem to hold great promise for the treatment of bacterial infections. 

O and i'd used both. When the path to Best mgt practice is unclear we still have to do somtehing.

BMP = Best Means Possible


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## S Mc (Oct 27, 2008)

Thinking through these options some more...

The OTC will suppress symptoms only, not cure the disease. So the disease is still within the tree available to be transmitted by leafhoppers or root grafts. It is an annual injection, with the resultant potential injury to the tree and annual expense to the owner. 

Cambistat will slow growth, thereby supplying less succulent new growth to attract the leafhoppers; again will cause a suppression affect NOT cure the disease. It reportedly enhances the tree's defences and provides drought tolerance; drought stress being a major stressor involved in succumbing to BLS. But is available as a basal drench or soil injection so is not causing an injection site injury to the tree and is applied once every 3 years. Studies have shown Cambistat to be effective on the red oaks (per my source), of which Pin oak is a member.

So I would say that all this information should be explained to the owner and get them involved in the decision-making. How committed are they? Will they stay with a program long term? I don't know what each of these treatments cost, so do not know how that translates financially to the homeowner. 

Again, I would be improving the cultural environment as best as possible whatever the treatment. But I appreciate learning about all these options. Thank you everyone for all the information.

Sylvia

P.S. So Treeseer, evidently you were posting while I was and I didn't get to read your post until after I submitted mine.

So Cambistat is a fungistat not a fungicide? Thank you for the clarification!


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## Ed Roland (Oct 27, 2008)

S Mc said:


> P.S. So Treeseer, evidently you were posting while I was and I didn't get to read your post until after I submitted mine.
> 
> So Cambistat is a fungistat not a fungicide? Thank you for the clarification!



"Paclobutrazol and flurprimidol are chemically related to certain fungistatic compounds, while trinexapac-ethyl is not and exhibits little fungistatic activity. *Paclobutrazol is a triazole *and, as such, is structurally related to several important turf fungicides."
H.T. Wilkinson, J.M. McMeans and T.W. Fermanian,University of Illinois

"The *triazole plant protection fungicides *include epoxiconazole, triadimenol, *propiconazole*, cyproconazole, tebuconazole, flusilazole and paclobutrazol."
From Wikipedia

big dif tween "demonstrating a fungistatic property" and actualy being one.



I have been "on the fence" about using cambistat in conjunction with OTC. There is quite a bit of anectdotal evidence. I like the arguments to use it as posted here. It is worth noting that the largest science based residential tree firm out there stops short of recommending OTC w/ Camb. 

"Water loss may be reduced during droughts on treated trees. This may be desirable for nonirrigated trees and tree  infected with Armillaria, Bacterial Leaf Scorch or Verticillium wilt." BTRL

Their official recommendation is OTC.



treeseer said:


> O and i'd used both. When the path to Best mgt practice is unclear we still have to do somtehing.
> 
> BMP = Best Means Possible



Ok, I think that tips the scale.


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## appalachianarbo (Oct 27, 2008)

I'll be speaking with the homeowner tomorrow. I'll present the options, including doing nothing at all and planting a replacement now. 

My per-treatment cost for OTC = $188 (This is retail thru Sherrill - my wholesale supplier will be getting back to me with a price tomorrow). My per-treatment cost for Cambistat = $79. That works out to $26 per year as opposed to $188 per year. Both would be $214/yr. Also keep in mind these are my costs, not what the homeowner would pay. I'll recommend cultural improvement with any treatment (or non-treatment). 

This has been a great discussion. Thanks


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## Chris Francis (Nov 3, 2011)

*Plant Growth Regulators / Tree Growth Regulators*

I have an up-to-date post here you may be interested in:

http://www.arboristsite.com/commercial-tree-care-climbing/105457.htm


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## Urban Forester (Nov 15, 2011)

Chris Francis said:


> Randellso,
> 
> Did you mean to post this in this 3-year-old thread about bacterial leaf scorch?



Chris,
I'm pretty sure he's just a spammer. He cut and pasted in 4 threads yesterday.


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## Chris Francis (Nov 15, 2011)

Urban Forester said:


> Chris,
> I'm pretty sure he's just a spammer. He cut and pasted in 4 threads yesterday.



That just doesn't even make sense. There is no web address or get-rich-quick scheme. Heck, he isn't even claiming to be a prince from the Middle East with millions of dollars that simply need a U.S. bank account. But, now that you mention it, that post did look strikingly familiar. Oh well, maybe all the bacterially-scorched leaves will be falling off soon enough.


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## Urban Forester (Nov 16, 2011)

I was hoping for 3 russian wives, oh well. His profile has links to hot tubs and barbeques not a bad combo...


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## Ed Roland (Nov 16, 2011)

I believe it's actually called _subtle spamming_. He must get traffic from these signature links to even go through the effort. Interesting how junk evolves as the economy suffers.


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