Uninvited Guest


A fungus is sprouting up around Southern California, snaking around stucco and brick to get to its daily meal--the wood in and around your home.

When the feast is over, once-solid walls and floors are left mushy enough to put a pinky finger through, and once-secure property owners are left scrambling to come up with the thousands of dollars needed to repair the damage.

In the last two decades, Meruliaporia incrassata--an orange-colored, mushroom-shaped fungus--has shown up with more frequency in houses from San Diego to Northern California. And because most homeowners, pest control inspectors and contractors are unfamiliar with the unusual growth commonly called poria, the fungus spreads untreated and unchecked through houses big and small, an equal-opportunity menace.

“It’s a rare fungus, but it’s as common here as anywhere in the world,” said UC Riverside plant pathology professor John Menge. “It’s also the most devastating wood-decay fungus of houses that we know of.”


“The bad news about poria is that it’s hidden and it spreads fast, but once you find it, it can be controlled,” said Wayne Wilcox, a UC Berkeley forestry professor.

It sounds like science fiction and looks like it too, but poria, like all decay fungi, is an organism that needs moisture to break down and utilize wood as a food source, according to forest product experts at UC Berkeley.

But unlike other decay fungi, which tend to destroy only a six-inch area around a plumbing leak or wet window sill, poria has the capacity to begin in wet soil--usually under a newly installed patio, new landscaping or a room addition--then travel to dry wood by pumping water through a root-like system. Far from its original water source, the fungus continues to feed on the new supply of wood.

Donna Kingwell, a spokeswoman for the state’s Structural Pest Control Board, said the agency “is keenly aware of the potent problems of poria, especially in the southern part of the state.”


La Canada homeowner Laurie Rodli is also keenly aware of poria’s destructive potential.

The mother of two and her husband, Eric, moved into their 50-year-old remodeled home early in 1994. Three months later, she noticed stale-smelling, fuzzy growths cropping up in some unpacked boxes in the dining room.

When she opened the boxes, she discovered their interiors were covered with smelly, orange flowerets and they were stuck to the floor.

She emptied the boxes and threw them away. But the following summer, Rodli tried to open the drawers of a spare dresser in her son Mark’s closet, but they were glued shut. Pulling the dresser away from the wall, she discovered that the back of the bureau had been eaten away and the closet wall and floor were warping.


A contractor cut out the floor of the closet and a portion of the bedroom to discover that the fungus had rotted the subfloor.

“We couldn’t find a leak, even under the sink and toilet. What was causing this?” Rodli wondered.

Like the voracious plant in “Little Shop of Horrors,” the fungus showed up again months later--even after the affected areas had been treated--this time warping the dining room floors and walls.

“We just thought we had some new dry rot on the dining room French doors,” Rodli said. “Unfortunately, we let it go.”


Last July, she called a new contractor. As he inspected the house, his foot fell through the living room floor. He ripped up the dining-room and living-room floorboards, where widespread damage was revealed: The fungus had crept through half the house, eating away the subfloors and even parts of the fireplace.

In November, Luis De La Cruz, a Van Nuys pest control specialist and, according to UC Berkeley’s Wilcox, one of the few inspectors in California who has learned to recognize the fungus, examined the property and broke the news to the Rodlis: The mysterious fungus gobbling up their house was poria, and eradication would involve opening up walls, tearing up floorboards and demolishing the back porch.

They would also have to ventilate the foundation of the house, install an irrigation system in the backyard and repair the interior damage.

The price tag: at least $60,000, exclusive of landscaping, her contractor estimated.


“I cried off and on for two days while my kids were at school,” Rodli said. “The chaos was unbelievable. I’d just burst into tears every time I looked around.”

De La Cruz has experienced this reaction all too often in the last few years.

"[Poria] is a monster that no one wants to hear about,” De La Cruz said. “We can look at a house during an inspection and everything’s fine. Six months later, it has wreaked havoc. It’s scary.”

The pest control inspector saw his first case of the fungus on the lattice work of a house in 1969. It dried up and quickly disappeared, so he didn’t think about it again until 1979, when he was asked by a Los Angeles Department of Building and Safety supervisor to check out an Encino home infested with an unusual growth.


UC Berkeley’s Wilcox helped De La Cruz correctly identify the fungus and suggested ways to eradicate it.

By 1992, after successfully identifying and treating a number of cases of poria around Southern California, De La Cruz had established a reputation as a poria expert, Wilcox said.

First reports of Meruliaporia incrassata destruction surfaced in 1913 in the southeastern United States, where forest products--the suspected origin of the fungus--abound.

There is no record of the first reported case of poria in California, according to Wilcox, but scientists discovered the telltale spores on three coastal redwoods in 1924.


Infestations of poria are rare--only 15 cases were reported statewide by 1968, according to a U.S. Department of Agriculture study.

Poria experts believe that more recent increases in California can be traced to new building standards established after the oil crisis in the late 1970s. To conserve energy, houses have been built close to the ground, where the fungus has easy contact with wood. Newer homes also tend to have poor ventilation, Wilcox said, allowing poria to thrive.

Because neither the state nor Los Angeles requires an inspection for poria when homes are bought or sold, or when they are under construction, no state or city agency keeps accurate track of cases, according to the state Structural Pest Control Board and the L.A. Department of Building and Safety.

However, De La Cruz said, in the last year alone, he has identified about 80 cases in California, and UC Riverside’s Menge said he expects a bad infestation this fall because of last winter’s heavy rains. “It takes awhile to get started after the rains.”


When poria does invade a house, it’s almost always catastrophic, said Mississippi State University wood technology professor Terry Amburgey.

“The fungus will [infiltrate] a foundation--wood or concrete--and pretty soon the entire house goes,” Amburgey said.

That was nearly the case at a 22-unit, beachfront Malibu condominium complex, whose wood piles supporting the building were destroyed by poria.

Los Angeles forensic architect Mark Savel discovered the huge fungal infestation in the building’s foundation last year, and quickly realized it had spread throughout the complex.


Despite the obvious source of water near the Malibu building, the fungus was not fed by the ocean, but by a subterranean septic system. Foundation repairs cost $600,000.

The homeowners association members, whose insurance policies did not cover fungus infestation, were forced to pay the expenses out of pocket.

One of the most serious roadblocks to eradicating poria is convincing homeowners that a patch job will not cure the problem. When they hear about tearing open walls and digging up foundations, they seek another opinion, often from termite inspectors and contractors who have no experience in treating the fungus.

“I feel there are times when I’m the messenger who will be shot,” Savel said. “Homeowners reject reports about a degraded floor joist until they see the wood crumbling in my hands. They want to make a quick repair. All I can do is explain the alternative, which is never good.”


Fears of plummeting property values, coupled with the shame attached to publicly acknowledging a fungal infestation, often result in homeowners rejecting experts’ advice altogether, even when the house is in danger of collapse.

De La Cruz fears that will soon be the case with a large two-story Northridge house he recently inspected.

The owner rejected his poria diagnosis--and the estimated $100,000 cost to eradicate it--and sought three other opinions until the owner finally was told what he wanted to hear: The tennis-ball-sized growths sprouting up like toadstools around the window sills, doorjambs and supporting columns were the result of badly aimed sprinklers.

According to De La Cruz, the poria was so widespread that anything short of its immediate eradication may soon result in the collapse of the home.


The Northridge resident, like several other homeowners contacted for this story, refused to be interviewed.

Homeowners who decide to eradicate the fungus are hit with a one-two punch: First they’re told that the repairs will cost thousands of dollars, and then that their insurance policies may not cover it.

Since poria, a hidden problem that develops over time, is discovered long after the destruction has begun, most claims are rejected.

Joe Howard, a Sherman Oaks resident, fought his insurance company and won.


Howard discovered the telltale orange ooze growing at the intersection of the wall and floor in his daughter’s bedroom 2 1/2 years ago.

“I thought it was cat vomit,” he said. “After we stripped the walls away, we found the stuff everywhere. It’s like a parasite or a vampire attached to the house.”

With an estimated cleanup cost of $15,000, Howard called his State Farm Insurance agency, which turned down his claim.

After the Consumer Services Division of the California Department of Insurance refused to act on his behalf, Howard told State Farm he intended to pursue his claim further. The insurance company agreed to an arbitration hearing to settle the matter.


Howard won his case after proving to the judge that the poria infestation caused the collapse of his home, a clause included in his homeowners policy.

“I had to bring in a pamphlet put out by the [U.S. Department of Housing and Urban Development] that explains what [poria] is, just so the judge would understand the severity of it,” Howard said.

State Farm spokesman Phil Supple said the insurance company still covers structures that collapse due to hidden decay, but added that the definition of “collapse” is decided on a case-by-case basis.

A claim for Rodli’s repairs, which the family initially financed themselves, was settled with 20th Century Insurance Co. in May. The checks, which covered about half the costs, arrived six months after the work had begun.


“We had to eat, sleep and breathe this mess for so long,” Rodli said. “Our kids were asking if there would be any money left over for their college. When I looked at my house literally crumbling, I wondered.”

The Rodlis’ new homeowners policy specifically excludes future coverage for loss caused by mold, rot and fungus.

A 20th Century spokesman declined to discuss the case, but he did confirm that most insurance companies are unwilling to cover damage that is not the result of a sudden catastrophe, such as fire or burst water pipes.

“If [poria] becomes a widespread problem, insurance companies, trying to meet the needs of customers, may have to change,” said Ric Hill, vice president of corporate relations at 20th Century Insurance Co. “But the process won’t change overnight.”


Rodli, meanwhile, is enjoying her newly landscaped backyard, and is trying to put the five-year episode behind her.

“Now that it’s over, I can breathe easier,” Rodli said. “I hope that no one I know ever has to go through this.”


Managing the Fungus


People with mold and mildew allergies are advised to avoid contact with the material during cleanup. Inhalation of spores can lead to inflammatory reactions, such as chronic sinusitis and bronchitis.

Signs of Infestation

* Separation of baseboards from the floor.

* White threadlike membranes forming fan shapes under wallpaper or floor coverings.


* Swelling and crumbling of plaster or drywall.

* Mushroom-shaped fruit bodies on rotten wood around window sills, cupboards or the underside of flooring.

* Irregular vine-like roots branching in the soil and extending to foundations, framing or the subflooring.



Methods of Control

* Locate and remove the fungus’ source of water, usually near the point of greatest decay, and repair any plumbing leaks.

* Cut the roots, or rhizomorphs, and scrape fungus growths from the foundation.

* Remove contaminated soil from the property.


* Dry out all affected areas, from floor joists to ceilings.

* Replace decayed wood with pressure-treated lumber.

* Once the fungus is eradicated from a home, the property should be inspected by a poria expert once a year.



Information Resources

UC Berkeley’s Wayne Wilcox and pest control specialist Luis De La Cruz give periodic workshops for general contractors and pest control inspectors on the identification and treatment of Meruliaporia incrassata. For information, call the state Structural Pest Control Board, (916) 263-2540.

The UC Forest Products Laboratory in Berkeley has also set up a telephone number where people may leave their addresses to get information mailed to them about poria: (510) 215-4261.

Sources: U.S. Department of Agriculture, the U.S. Forest Service, the U.S. Department of Housing and Urban Development, and the California Department of Health Services