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Meruliporia fungus signs in a building (C) Daniel Friedman at InspectApedia.com Meruliporia incrassata - "Poria" & Termites
Symbiosis or Interference?

  • POST a QUESTION or COMMENT about the relationship between termites and the house eating fungus: Meruliporia or Serpula molds in buildings

What is the relationship between termites that attack wood structures and Poria or Meruliporia fungus that can also cause rapid extensive damage and that may be found together with termites in some buildings?

This article series describes Meruliporia incrassata or "Poria" Meruliporia incrassata, previously named Poria incrassata which is better known among reporters and repairmen who see the public pale at reports of how the "house eating fungus destroys a home.

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Poria or Meruliporia and Termites

Meruliporia and termite damage in a wood-framed home (C) InspectApedia.com ChuckWhen attacking wood in buidings, do termites cause, or benefit from the presence of Meruliporia fungi, or are they repelled by "Poria" or other fungi? Research provides some interesting and sometimes contradictory answers, as we explain here.

The water-conducting fungus, Poria incrassata (Berk. and Curt.) Burt, causes the most spectacular decay of wood in buildings in the United States. It produces large, tough, water-conducting strands (rhizomorphs) which, when rooted at a constant and abundant supply of moisture, can wet wood of a variety of species many feet away. - (Verrall 1968)

At page top we show an example of Meruliporia in an old building.

Question: Can Termites bring in or facilitate Poria?

2020/11/19 Chuck said:

I have extensive "poria" damage in our home. In addition to Extensive Termite damage. Basement construction. No water leaks.

Easily inspectible by competent termite technicians. It appears that Termites have been present for many years, more than 10 although responsible pest company never noted any termite activity.

[Click to enlarge any image]

Entire rear of house across 54' damaged, inwards around 13'. Basidiospores tested positive.

Question- Can Termites bring in or facilitate Poria?

The damaged wood clearly shows termites present prior to poria damage, as if to say that the poria was so aggressive it ran off the termites.

Regarding the next photo below:

Here is another picture of poria and termite damage together. Brown checking on outside of wood, termite mud inside of wood.

Moderator reply: Possibly but research suggests that Meruliporia repels termites

Chuck

Thank you for a helpful and interesting question about Meruliporia - or "poria" damage and its effect on termites.

I have found no scholarly research that blames poria damage itself on termites themselves nor vice versa though at least one of the references I cite below notes:

Meruliporia and termite damage in a wood-framed home (C) InspectApedia.com ChuckSome biologists, however, believe that the fungus so alters the structure of the wood that the termite is able to attack the wood. Other biologists feel that the wood itself, which the termites eat, does not supply proteinaceous material; and the termites cultivate the fungus in order to obtain the necessary protein for growth.

It has been discovered that, quite surprisingly therefore, termites may be repelled by the fungus Poria monticola. - (Lund 1966).

The building-environment conditions that invite termites might certainly also invite fungal contamination and rot, of which poria is one of the nastiest as it's rather hidden from view until it gets pretty bad.

And there is indeed evidence that the presence of Poria monticola, (and perhaps Poria incrassata) may repel termites!

A termite inspector doing probing might miss the meruliporia damage if she probes an area where damage is modest - spotting those mud tubes and missing the fine yellowish powder that is actually mold spores, characteristic of poria damage to wood.

Your suggestion that the "poria" drove off the termites is interesting and has merit. Kudos to you for thinking of it. In fact that theory has been expounded by entomologists and mycologists before (Lund 1966).

Once wood is sufficiently decayed it may be of no interest to termites as there's no stable passage to create through powdery muck, though I'm not sure experts would agree with me. (Matsuo 1973).

And meruliporia's by-products may indeed repel termites.

Nevertheless, nobody would want to permit their house to actually rot from meruliporia as a treatment for termites!

Reader follow-up:

2020/11/22 Chuck said:

First- thank you for a very thorough response. Due to ongoing litigation, I suspect this will be a hot area of debate.

I have attached a picture of an example of poria and termite damage coexisting [photos shown above - Ed.] (At least at some point in time)

Not sure if you can tell, but the pic shows termite damage and you can see white on the same piece of wood.

I wonder if the fungi is brought in from the termite tubes?

The tube in fact protecting the termites but also spreading the fungus. Everywhere there is termite damage, there is fungus.

Moderator reply: relationship of termites & Meruliporia sp. fungus

Yellow Poria fungus in a building (C) Daniel Friedman at InspectApedia.com ...Signs of risk of termite attack © Daniel Friedman at InspectApedia.com

Above: yellow poria fungus in a New York home and termite mud tubes and damaged wood framing. Poria damage and termite damage may overlap in a building.

Chuck, I've certainly found Meruliporia damage in buildings where there we could not see evidence of accompanying termite damage, but note this remark:

Some biologists, however, believe that the fungus so alters the structure of the wood that the termite is able to attack the wood.

Other biologists feel that the wood itself, which the termites eat, does not supply proteinaceous material; and the termites cultivate the fungus in order to obtain the necessary protein for growth. (Lund 1966) ( Nobre 2010) (Korb 2003)

It is also worth noting that Poria incrassata damage can occur rapidly and often in new construction.

Records on the occurrence of Poria incrassata in houses are summarized in table 3. When the attacks occurred most of the houses were only a few years old or had received recent structural changes. This circumstance strongly supports the view that infected lumber is an important means of introducing the fungus into buildings ( 19, 24, 25, 51 ).

Baxter ( 3 ) suggests that the occurrence of P. incrassata in the North may be largely due to the importation of infected lumber. Very likely infected lumber is not the only means of spread.

The house at Dothan, Ala ., had a recent addition but the decay started in an older part where a coal pile on wet soil had been in contact with the siding. The fungus may have been introduced on the coal. The infection was adjacent to the bathroom, where a plumbing leak constantly wetted the substructure and allowed the fungus to exist after the coal had been removed .

...

For all the houses listed in table 3, the probable points of entry were:

Constant sources of moisture were :

Sometimes two or more factors were operative . - (Verrall 1968)

The surface of the soil was wet under 56 percent of the houses with crawl space, moist under 8 percent, dry under 12 percent, and undetermined under 24 percent .

Drying the crawl space by drainage is safer than reducing humidity with a soil cover.

The fungus can maintain itself in wet soil under a cover ( 12 ) and will attack covers containing cellulose fibers ( 1 ).

Crawl - space ventilation was less important than previously suspected. Ventilation was good under 68 percent of the houses, fair under 16 percent, and poor under 16 percent. However, some of the most destructive attacks occurred where the crawl - space soil was wet and ventilation was poor.

Severe damage was found in houses with the best substructure ventilation, i. e ., open - pier foundations, but here an abundance of water was supplied by well - developed rhizomorph systems . - (Verrall 1968)

A remote inspector is never a substitute for an onsite expert, but it's possible that I can see and comment on details in your photos that may be useful.

What are the conditions under which the two photos were taken? In particular, has only demolition been done to expose damage, or have some repairs already begun? I ask because I see what looks like newer material in some areas of your photos.

What is the specific point of disagreement or litigation?

Reader follow-up: issue of inadequate termite inspection / treatment

2020/11/23 Chuck said:

What are the conditions under which the two photos were taken? In particular, has only demolition been done to expose damage, or have some repairs already begun?

Yes- damaged wood in some load bearing walls was removed and temporarily repaired in Jan 2019. We only recently opened up much larger areas that exposed additional damage. We will not repair, or possibly replace the structure until a determination has been made in our case.

What is the specific point of disagreement or litigation?

We constructed the home in '99. Hired a Termite pest control company for pre-construction treatments. Then paid them annually for termite inspections up until damage discovery in Oct 2018.

House sits on an unfinished basement. A porch was added to rear of the home in 2006. Their position is that because the porch was added and they did not treat the porch, they have no responsibility for the damage.

We contend they are 100% responsible for the termite damage and any other associated damage as result of poor inspection practices. There are many facts in this matter supporting our position that I should not get in to here at this time.

The piece of 2x4 in the picture standing on end was installed in 2016 when we remodeled our Kitchen. That is 4 years ago and you can see how much termite damage occurred. Is is roughly 12' to the interior of the home from the foundation wall. The poria adjacent was not present to our knowledge at the time of this remodel. Yet the surrounding floor structure is covered and growing an active basidiospore in this area. So, how did it get there?

[Below abstracted from private email]

One of our termite experts is of the opinion that termites do not cause Meruliporia infestation in buildings, as “… Poria requires a water source to remain active. Termites do not provide enough moisture for that to happen” …

Our engineer is of the opinion that termites do bring or could facilitate “poria” infestation.

Moderator reply:

Termite damage case © Daniel Friedman at InspectApedia.comIllustration: yellow "material" and termite damaged wood flooring studied by the author and discussed

at TERMITE DAMAGE INSPECTION

Chuck

Your added details are helpful. What follows is OPINION based on the limited data at hand in this discussion.

Hiring a contractor for pre-construction treatment telegraphs that most-likely everybody involved knew that the home was being constructed in an area of Virginia or at a particular neighborhood prone to termite-attack.

I haven't seen any details about how this home was built but if it were my project I'd have taken steps to make the home as resistant to termite attack as I could, including choice of materials, termite shields, and attention to drainage, roof runoff control, water and moisture control, use of treated wood in higher risk locations such as sills and lower walls (resistant doesn't mean a termite won't build a mud tube over a PT wood sill).

The addition of a porch can restrict access to and so limit treatment of an area of a building. Failure to warn you of that problem and possibly failure to construct the porch to either provide access or to make the building structure termite resistant are disappointments.

The question of whether or not the inspector's services were deficient in finding and addressing active termite attack surely must be determined by the inspection history, the termite and Meruliporia damage history, and where damage appeared for visual detection and when.

The building is located in Virginia between Richmond (my home town - DF) and Williamsburg, an area of temperate climate. In that area the termites commonly found are either the eastern subterranean termite or the formosan termite. Either of these can cause very extensive damage to wood structures.

---- from private email ----

I remain professional neutral in discussions and disputes like this one, as key to retain credibility. With the reclama that of course I can't be as smart as your onsite experts, I comment:

Below are some comments based on what you've described about the building and its inspection history and on your posing a question of the relationship of termites and Meruliporia and whether or not the termites "brought in the Meruliporia" to the building, for which you report having got conflicting opinions.

1. Stating that "Poria requires a moisture source" and "Termites don't provide enough moisture for Poria" might let one infer that termites do not "cause" Meruliporia infestation but: Termites don't have to "bring in the water" to support Meruliporia.

The particularly onerous feature of this fungus is that it can travel great distances inside wood members, far from its water source, though it still requires a moisture source.

That source can be quite remote from the extremes of the damage. It is unnecessarily confusing and probably not useful to pursue the water argument to decide who came first, termites or fungus. Moisture or water affect both. If both are present there is or was a moisture source.

In sum we should not be surprised to find all three situations:

2. Termites *might* indeed bring in or cultivate Meruliporia in wood, as you can read in some of the scholarly research on this topic going back at least to the 1960s and that I cited earlier, but that research did not claim to be conclusive.

There is research pointing out that the fungus might both help (digest wood making it easier for termite consumption) and hinder (repel termites by chemicals) termite presence in wood, so unless we find some additional or more-recent and more-conclusive research the resulting answer should remain inconclusive.

And there is absolutely evidence that termites have been shown to cultivate other fungi in their colonies. So it’s not a spurious claim.

3. Meruliporia damage occurs without termites

I have absolutely found extensive Meruliporia damage in wood structures where termites were not present

4. Termite damage occurs without Meruliporia sp.

I have absolutely found termite damage in wood structures where we found no Meruliporia - just how common that fungus is in homes probably varies by geographic area as well as, of course, individual building conditions.

Swarming Termite photo of Alates (C) InspectApedia.com Grudzinski D

Our photo of a swarming (winged) termite crawling across the finished floor in a home is provided courtesy of New Jersey home inspector David Grudzinski.

5. Moisture is key, along with wood-soil proximity or contact, aided by sheltered attack paths - the fungus prefers dark spaces to ones that are well-lit.

Temperature
ism also a factor in the activity of both organisms, and it is possible that where Poria and termites co-habit wood in a structure the temperature-regulating effect of the termite colony may help keep the temperature within the narrow range required by Meruliporia for active growth just as the heat of fermentation in the fungus may support the temperature preferred by termites [opinion-DJF based on ( Lüscher 1961)].

But for both termites and fungal infestation in buildings, moisture is a key. Sometimes significant and pointed out by Verra (1968),

Sometimes the source of constant water occurs away from the point of initial attack. For this reason just fixing an outside or building perimeter water problem is not alone a reliable control for Poria infections.

For termites, probably more than for Meruliporia wood-soil contact or wood-soil proximity are key determinants. We find termite mud tubes on the outside, inside, and even inside concrete block or in cracks in poured concrete reaching up from soil into wood structure, but having inspected thousands of buildings and seen lots of insect and mold or fungus damage, I emphasize that proximity of wood to soil and moisture or water sources is highly correlated with any wood destroying insect attack,

while on the other hand, in general where mold contaminates or infects a building, the moisture source can be anywhere, more subtle, and wood-soil proximity is not a determinant.

6. Which came first Mold or Termites?

I am doubtful that a mere visual inspection of wood can possibly determine "who came first" the termites or the fungus.

These are completely different organisms that for a host of reasons may propagate in wood at very different rates over different intervals, affected by many external conditions (temperature and moisture, being the two key ones).

Poria is killed in wood at temperatures ... considerably below those required for commercial kiln-drying of lumber, [30 min. at 50C]. (Verrall 1968)

High moisture is also required to sustain the fungus.

The rot caused by Poria incrassata is often called “ dry rot, ” presumably because the fungus, by conducting water, attacks wood that is normally dry. During active decay, however, the wood is moist to the touch.

Decay caused by many other fungi in wood made wet by rain seepage is also called dry rot. Between rains the wood so attacked may be dry for long periods ( 50 ), during which these infections remain dormant. In contrast, P. incrassata survives only a short time in dry wood. Regardless of the fungus alluded to, the term dry rot is a misnomer.

Poria incrassata is extremely sensitive to drying. It was viable in only 53 of 105 samples of rotted wood received at the U. S. Forest Products Laboratory. In naturally infected wood, it could not survive 32 days of air - drying.

All artificial infections were dead in 1 day at 30 percent relative humidity, in 5 days at 65 percent, and in 10 days at 90 percent ( 42 ). Findlay and Badcock ( 20 ) reported that both P. incrassata and Merulius lacrymans are sensitive to drying .

In contrast, such fungi as Lenzites trabea and L. saepiaria lived at least 9 years in wood at 12 percent moisture content. (Verrall 1968)

The same author noted that Poria incrassata tolerates some fungicides but ....

Practical significance of the tolerance to copper fungicides is uncertain. No failures of preservatively treated wood in buildings have been reported. In soil - block and stake tests the treated wood was subjected to attack under conditions more conducive to decay than are likely to occur in buildings.

At present, there is little justification for excluding any com monly accepted preservative in construction. In repairing damage by Poria incrassata, however, wood treated with a noncopper fungicide should be used . (Verrall 1968)

7. Stop the fungal and termite attacks & repair the damage

Watch out: Waiting too long to stop ongoing damage of a building during litigation might raise a new issue that the building was not perserved or damage interrupted so the damages were unnecessarily increased; discuss this with your lawyer.

To stop the Meruliporia infestation most-likely you will need to remove infected wood close to any moisture source as well as wood that is sufficiently damaged as to no longer be functional as structure, flooring, etc..

Because of the way that fungus spreads distant from its moisture source (up to 25 ft) that can mean extensive demolition, basically removing badly damaged, wet material as well as infected perimeter material near any water or moisture.

For some more-sophisticated wood testing methods see the articles listed starting

at WOOD STRUCTURE ASSESSMENT - home

To stop a termite infestation we usually rely on cutting off the termite path to ground (presuming yours are termites coming up from soil, as there are some exceptions to that passage)

(I remove infested wood, add shields, fix the moisture source, repair with treated wood) and typically the contractor wil have a professional apply chemical poisoning of the soil - your termite expert will be able to advise you on termite control for the repired building.

(Notice that they no longer use the word "exterminate" but rather "control" - a distinction that in my opinion is significant in forming one's expectations.)

But a WDI inspector may not alone be equipped to assess the extent of damage to the structure - you'll need an experienced repair contractor who knows how to recognize damage and how to help you decide how much damaged material must be removed.

For legal and resale purposes you'll want to keep a thorough and well-documented record of what work you have performed.

8. If you want to pursue the termite-fungus distinction you've made, which IMO is not likely to be helpful and may simply confuse a court until it’s tossed out, you might want to try contacting some of the mycologists and entymologists who work in the field.

I'm unclear why the which-was-first argument is critical in deciding how to proceed.

If your dispute is about accountability for the discovery of or reporting of termite damage there are usually far less fragile arguments available to sort that out.

I hinted at this line of reasoning when I asked about what looks like pressure treated or new lumber in some of your photos. (You answered that - you’re the original owner, it’s new work, and there were regular ongoing WDI inspections).

Photograph of  termite damage to the floor structure of a 1920's home.9. Should an inspector have seen and reported termites?

An expert inspection of a building can usually find unambiguous visual evidence of conditions that indicate wood destroying insect infestation; finding Meruliporia damage is more difficult until the damage is rather advanced, but at that advanced state that, too, is visually obvious.

Often building inspectors and termite inspectors will probe high-risk areas or suspicious areas of wood framing, though during a pre-purchase home inspection a home inspector would not be expected to probe any finished-surfaces where such might cause even cosmetic damage unless that investigation has been agreed-to by the building owner.

Details are at TERMITE DAMAGE PROBING

Knowing of the possibility of Meruliporia infestation and having examined its spores in the lab Iearned to be alert for “yellow dust” in buildings.

For example I found yellow “dust” on the floor of a kitchen sink base cabinet, confirmed in the lab that it was Meruliporia incrassata spores, and ultimately correlated that dust with extensive Meruliporia damage in the building. [By the time you find such spore dust deposits you can bet the fungal infection and so the damage are well-advanced.] That dust would not be a Meruliporia alert to most building inspectors.

Having fielded and adjudicated complaints involving home inspectors and others for a long time it is my opinion that we can state what's reasonable to expect something like this:

Standard of Due Diligence in Building or Termite Inspection Reporting

If, at the time of an inspection for condition "X" there was clear, unambiguous visual evidence, without having to perform destructive or invasive examination, that condition "X" was present, such that all the inspector had to do was direct his or her eye towards it, then the inspector employed for that purpose should have seen it and reported X and has fallen down on the job if X was not reported.

Exacerbating conditions also can arise, such as using an inspector who has conflicting interests with the client, for example a buyer is taking a chance when using a home inspector referred by a real estate agent (who is obligated to the seller).

You are welcome to print and make use of articles we've published on these topics as information sources; my credentials are at the website About InspectApedia.com page. But I am not and don't represent myself as a Meruliporia expert though I am indeed familiar with the topic as I've discussed and researched and written about it extensively.

Reader follow-up:

Chuck said:

..., absolutely incredible response! This helps tremendously. I will be sure to follow up as we proceed.

I do agree with your assessment that we must protect/preserve what is left.

Based on our new uncovered evidence, that is in fact what we are working on now.

For anyone who encounters this fungi, I can only hope and pray they take the necessary steps immediately to reduce additional damage and exposure. Unfortunately, I am finding there are little to no experts in our area.

This has made this matter challenging in our particular situation. Thank you for this FREE and HIGHLY EDUCATIONAL website. And thank you even more for your valuable time. -Chuck

 

Research on the Relationship Between Fungus, Poria or Merulipoira & Termites

White rot fungus cultivated by termites - Ohkuma 2001, cited & discussed at InspectApedia.com

Illustration: the symbiotic relationship between some species of termites and some white rot fungii has been widely studied; some of that work is cited below. This illustration is from Ohkuma et als (2001).

[Click to enlarge any image]

Termite cultivated mushroom bloom - Ohkuma 2001 cited & discussed at InspectApedia.com

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