Sep TCI mag "Ooze in the News"

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Guy Meilleur

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I'm usually later getting my issues of TCI magazine than other parts of the country. If anyone gets their issue and has a minute to take a look at this article, I'd like to get some feedback on it.

ANY thoughts on the approach, the strategy, the organization of the writing, the conclusions, the future implications, anything. For the Aug Arborist News article on heading cuts I got a little feedback; wish there was more.

The idea of cleaning out wounds and cavities has been controversial on this site and in the overall industry, so I KNOW there's got to be some reaction to this. Also I'm wondering if it's clear what's meant by "sinister symbiosis."

For the :alien: who don't get TCI or get it way late, I'll post the article below in two pieces:

OOZE IN THE NEWS

“Roll out those lazy, hazy, crazy days of summer; those days of soda, and pretzels, and beer!” as Nat King Cole sang way back when. Summer is also the time for other foamy stuff, the kind that has certain insects singing songs of cheer. However, this is not good news for the unfortunate older trees that serve as taverns for moths and hornets and other imbibing creatures. Tree owners who find these frenzied congregations on oozing lower trunks of their older trees often call arborists this time of year. But insecticide is not the answer, because the insects are only a sign of trouble underneath the bark. Oozing slime is a symptom of bacterial infection, and “…warm temperatures are favorable for the development of some bacterial diseases…” as John Lloyd notes in Plant Health Care for Woody Ornamentals.

A coating of polysaccharide, which is called a “slime layer” for obvious reasons, surrounds bacterial cells. When the bacteria multiply, they are forced out of the host plant and ooze down the bark. Dividing as fast as once every twenty minutes, they quickly build up their numbers to as high as a billion per milliliter. A cocktail of bacteria--Pseudomonas, Enterobacter and others--, yeasts and other organisms causes slime flux disease. Whether any of these organisms is particularly pathogenic, or it is simply the physical pressure caused by all of them multiplying that kills the bark, is not clearly understood. Fermentation produces gases such as methane and carbon dioxide, which increases the pressure that ruptures the bark. Many different microorganisms grow in the flux producing an indescribably foul or alcoholic odor that is hard to miss.

Different species of trees have different types of slime flux disease. The type that is found higher up in wounds and crotches of elms and poplars are considered relatively benign. They seldom seem to aggressively damage the bark. What damage occurs is well above ground level and considered correctable. They are located in Zones 2 and 4 as defined in Dr. Kim Coder’s Hazard Tree Evaluation form, published in 1990. On older oaks the disease is quite different; it is typically found between buttress roots. This is Zone 1, where damage and disease are considered critical. Previous physical damage or previous insect injury is seldom noted at infection sites on the trees studied. Like included bark in a crotch, the bark between buttresses seems to be squeezed. One theory is that the tree opens itself up to infection by wounding itself when bark is included, and the bacteria enter from the soil. This is confirmed by Dr. Alex Shigo in Modern Arboriculture: “Included bark between roots and root stubs are common underground infection courts.”

TO ACT, OR NOT TO ACT
The old practice of drilling into the infection and installing a drain pipe to direct the slime flux away from the bark can expand the infection court and worsen the disease. The wet, alkaline conditions at these sites is inhospitable to most decay-causing fungi, so one thought is to leave well enough alone. When armillaria fungus is found along with slime flux, more rhizomorphs are found outside the oozing areas. The “shoestrings” found in the slimy area are few and stunted.. Many insects that are harmless to the living tree—ants, termites, centipedes, sowbugs, for instance—can be found under the dead bark, but there is no reason to go after them. However carpenterworms, Prionoxystus sp., are also active in these infection sites. As Johnson and Lyons report in Insects that Feed on Trees and Shrubs, “Over a period of time the activities of the carpenterworm larvae may prove disastrous to the host tree…” The need to expose and treat this pest calls for the removal of dead bark. Bacterial activity and slime flux on older oaks can and does kill cambium, expanding the diseased area every year. So there is also a clear need for noninvasive methods to preserve the tree.

The first job is to find out which portions of the bark are dead. The first cues are visual; lesions bleeding with blackened sap at the margins of the diseased area. These lesions appear very similar to those caused by infections of fungi such as Phytophthora sp. Auditory cues are gained by tapping with a rubber or plastic mallet outside these lesions. A solid sound indicates living bark over solid wood. Tapping inside the lesions will produce a hollow sound, indicating dead bark. A stethoscope can be used to better hear the sound, but is not often necessary to detect dead bark. The next step is probing these areas with a blunt instrument such as a trowel or screwdriver. Remove all discolored bark down to the wood. In some cases this means removing a lot of bark. If the infection encompasses more than half of the trunk and decay is advancing inward, it is doubtful the tree will remain safe for very long. It is probably best to treat these unfortunate trees with a chain saw at ground level.

Cut around the infected trunk or branch until you come close to healthy cambium. Take care not to cut into healthy bark or wood. Excavation of wounds is still viewed with skepticism in some circles precisely because of the fear that careless digging will result in more damage. When most of the dead bark has been removed, a sharper tool will trim the edges of infected material. In Helping Plants Survive Armillaria Root Rot (November 2003 issue of Tree Care Industry), the author describes the excavation of tissue infected with the fungus Armillaria. Because bacterial infections seem less virulent, and do not cause wood decay like Armillaria does, a more cautious approach to tissue removal seems to be warranted. The goal is to come as close as possible to healthy tissue without cutting into it. A blunt-tipped knife, such as a linoleum knife, can trim the last scraps of diseased bark without scratching the wood. There is no need to trace the wound into an oval, because sap can flow laterally within the cambium. Careful removal of dead bark may reveal the cambial layer, still light in color and adhered to the wood. The more living cambium that is left, the sooner the tree can close its wounds. Rinsing off the last of the debris with a sharp stream of water from the garden hose or better yet a jet of air from a pneumatic tool will finish the excavation work.
 
Part 2

CHEMICAL CONUNDRUMS
Once the infected tissue is removed the area can dry out, making the environment more inhospitable for the bacteria. Some publications recommend sanitizing the area with a 10% bleach solution. Some bactericides listed for other bacterial tree problems contain 9.5% propylene glycol, so they can also do a good job of sanitizing the area. Both these chemicals are very toxic to bacteria, but unfortunately they are also toxic to plants. Applying either to tree wounds is very risky and not recommended for this disease. If holes from woodboring insects are found, they should be excavated of loose material and probed with a thin tool such as a coathanger or a flexible wire. The goal is to either crush the pest, or at least clear a channel for a secondary attack with air or water or pesticide. No sealant or pruning paint is ever recommended for this condition, even after the surface has dried. As it’s been said for twenty years, any compound that can seal out problems can seal in problems. Light and air will dry out the area over time; invigoration of the root system can speed compartmentalization.

Fertilization of diseased plants has recently become highly controversial. Some large declining oaks that received a “stress treatment” of high-nitrogen fertilizer injected into the soil looked great a year afterwards. Soon after, they succumbed to Phytophthora and other decay organisms that thrive on excess nitrogen. As always with any stressed plant, the soil should be tested and any nutritional deficiencies cautiously corrected. The elements most lacking in many soils are oxygen and organic matter, so aeration of compacted areas and general mulching are often recommended. Inoculation of soil around the trunk with beneficial microorganisms is sometimes done to prevent infection by basal decay organisms, the “buttrotters”. This practice is based on the premise that pathogens will be less able to take hold in the basal area if there is a healthy population of microbes that are symbiotic with the tree. Inoculation is also an intriguing possibility for prevention of bacterial infection. However, some of the same genera of bacteria present in the disease are also present in the inoculant. A better understanding of the disease is needed before these inoculations are done to prevent bacterial disease.

In the course of excavation, any infected sites at ground level will require the removal of earth from the base of the tree. Small roots may be removed in the process, but care should be taken not to nick any woody roots. If fungal pathogens are identified, the surrounding soil can be drenched with a listed fungicide, following label directions. Air and light are the enemies of most fungal and bacterial organisms. Therefore, coarse stone inside a layer of landscape fabric is often used to replace the excavated soil. This prevents mulch and debris from coming into contact with the wound, and makes it easier to inspect the wound on followup monitoring visits. Trees are best revisited in early summer, when the slime fluxes again and the need for retreatment can be determined. According to research 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.

SURVEY SAYS:
For the last fifteen years we have treated this disease in central North Carolina. Most of the trees involved have been located on residential properties under a variety of conditions. To gain a better understanding of this disease, a site with a variety of mature specimens with a consistent microclimate and maintenance regimen had to be surveyed. The quadrangle at the heart of the University of North Carolina-Chapel Hill campus fit those parameters. School lore has it that Colonel Davie sat under a tuliptree on this site in 1792 and started the first public college in North America. A preliminary survey of the mature trees on this historic site was taken to assess the extent of this disease. The results follow.


6 of 23 Quercus alba, white oak, were diseased

2 of 8 Quercus phellos, willow oak

0 of 6 Quercus rubra, red oak

0 of 2 Quercus stellata, post oak

0 of 1 Quercus montana, chestnut oak

0 of 4 Ulmus americana, American elm

0 of 4 Prunus subhirtella, Higan cherry

0 of 5 Liriodendron tulipifera, tuliptree

1 0f 1 Carya tomentosa, mockernut hickory

The white oaks were by far the worst affected. Willow oaks were affected as frequently, on about a quarter of the trees in this sample. However, their infections were quite small, 2 and 4 inches wide, as was the hickory infection. Carpenterworm larvae were actively feeding under the bark at the two largest white oak infections, 13 and 16 inches wide. Larvae were not found in smaller infections, perhaps due to a sinister symbiosis between these two problems. The adult moth lays its eggs in the same time period that the slime is flowing. They are also known to generally prefer ovipositing in bark crevices, but the larvae can enter infected bark much more easily than healthy bark. They expand the infection as they feed, which attracts more adult moths to lay their eggs there, and around and around the cycle of destruction goes.

The lack of occurrence in the trunks of the elms demonstrates that this disease is very different from what most people call slime flux, or wetwood. “Slime flux” is a poor term, because many conditions involve oozing viscous liquids: resin flow from Scleridia canker in Leyland cypress or from borer galleries in other conifers, oozing gums in Prunus, wetwood from the xylem of elms and poplars, sap from all manner of wounds. Whether you call it slime flux or the White Oak Woes or the Bacterial Oozing Blues, treating this condition in a prompt and persistent manner can prevent fatal damage to magnificent old trees. Then you can relax in a hammock under their shade, safely enjoy a bubbly beverage, and listen to the birds thank you with their songs of cheer.
 
Sounds good to me Guy. I deal with "slime flux" in Siberian Elms and Globe Willows primarily in this area. In the Elms I usually advise an external scrubbing with bleach water at 1/16 or nothing-experience has shown little progression/bark dieback in this species. On the willows however the disease can quickly progress into a bark girdling killer. I excise dead bark and scrub with the bleach/water solution. Excising without the bleach has not proven effective on Salix for me. I think that the specific mix in the bacterial/fungal cocktail probably varies from species to species and tree to tree and so does the typical response to it.
 
Originally posted by Stumper
Excising without the bleach has not proven effective on Salix for me.
Thanks Justin, my experience is that the bleach speeds drying and disinfects. I've gotten flak about using it, so on some trees I don't, and have to repeat sanitation more often.

The flak mostly comes from the fear that bleach will be misapplied, and by dousing the cambium you can do more harm than good. I think this fear has basis but is overstated. When you disinfect willow how careful do you have to be to make sure you're keeping it on the wood and not on the bark? Does it matter; have you seen bark necrosis from bleach use?

"the bacterial/fungal cocktail probably varies from species to species and tree to tree and so does the typical response to it"

Varies widely, apparently. There's a bartender joke in there somewhere but I can't come up with it...
 
I try not to spill the solution everywhere but do get some on the bark . I haven't noticed much bark necrosis from the spillage. On the other hand-continued bark die back has occurred where the oxidizing agent (bleach) wasn't used or where the bark was not excised back to live tissue or VERY near to live tissue. You will note that my solution is considerably weaker than the 10% sometimes suggested. I suspect that it is still far stronger than needed. JPS had some info on bleach as a sanitizer a couple of years ago.-Bottom line was that the solution can be quite weak if it is allowed time to work. I've been hesitant to drop the chlorine percentage further simply because what I've been doing has worked.
 
Hey Rob, Have you used the HO3? Peroxide is a known oxidizer/disenfectant of course but it isn't as aggressive as 'Chlorine' so I wonder about effectiveness.
 
Hey Justin,
Hydrogen peroxide is equally effective in killing organisms, I have been using it for several years even to introduce needed oxygen into the root zone. The great benefit is that after the reaction there is no residual contamination and it reverts back into water. If you need a stronger mix buy it in 35% concentrate but make sure you are buying food grade HP.
 
The magazine just got delivered here. I'm pleased with the layout job by TCI. The last picture was the most important--is it clear to readers what "sinister symbiosis" is, and the cycle of destruction I'm referring to?

Are there more than 3 arborists on this site who are interested in managing trees with something other than a chainsaw?

I'm very grateful for the feedback re HO3; sounds like the best disinfectant to use on trees.
 
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About cleaning or doing things to cavities as first mentioned in the initial post:

What comes to mind is that water can freeze and expand.

I have seen a cavity dump about 8 gallons of water before when a climber drove the nose of his saw in a small location to let water drain from a Douglas fir that was topped and the top decomposed into a small pool about 70 feet up.

At times, I've wondered how much damage ice can do to a tree if there is a large accumulation and it freezes.
 
Originally posted by M.D. Vaden
At times, I've wondered how much damage ice can do to a tree if there is a large accumulation and it freezes.
not much since tree insulates and raises temperature and expands as the ice does. Since cavities are open expansion from freezing does not break, kind of like an ice tray in your freezer?

what part of the article made the most sense? the least sense?
 
The whole article makes sense. Your sentences are well formed.

Every professional may not know what a polysaccharide is, but you can't gut too much from an educational piece.

I like "larvae" with the "e" on it too.
 
Originally posted by M.D. Vaden
The whole article makes sense. Your sentences are well formed.
thanks, the whole thing flowed fairly easily. It's the first piece I wrote where I will come out with better than minimum wage paid, because it was familiar material and I didn't have to agonize too much about being outside the box.

Every professional may not know what a polysaccharide is, but you can't gut too much from an educational piece.
Yeah that was as technical as it needed to be. No need to get more into the chemistry than to say where the "slime" comes from. Which is good cuz I'm no chemist.
I like "larvae" with the "e" on it too.
The "e" makes it plural, if I remember my Latin right...So it was clear then that carpenterworms and bacterial infections are symbiotic? Good. Symbiosis is usually considered a positive thing, so I had to be clear that in this case it's destructive.

Do you get slime flux or carpenterworms in your white oaks in OR?
 
Just saw slime flux in an Oak for the first time last week. Had me scratching my head. I'm sure it's not the only one, but I've done 3000 pruning contracts since 1988 and that's the first I'd seen. Never saw it on the country clubs or university campuses I was at back to 1980,

Maples - a bit more frequent. I see a few each year. In fact, I wanted a photo on this on maple, and found two while doing an estimate this week.

I think our - Portland metro - worst problem is soil damage from construction.

There is promotion of protective barriers around trees in many cases. But what is not taken care of is protecting or improving soil for new trees.

What good is it to require 2 trees near the sidewalk if the soil is trashed? I'm not sure why the municiple urban foresters are not getting that concept through.

It would take a mandate to make it work. Contractors won't give a hoot unless it's mandantory.
 

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