RoguePundit

Sudden Oak Death Still on the Move

Unfortunately, the sudden oak death fungus continues to make its presence known in Curry County.  The spread of this incurable malady remains slow but seemingly inexorable because eradication efforts have never been aggressive enough--often due to limited and patchwork funding.  At the moment, authorities are awaiting federal stimulus money for some efforts.  Fortunately, the stimulus money doesn't require matching funds from the state...which is why several hundred thousand in federal grant money is going begging.  Last year, ODA and ODF had run out of money until the Legislative Emergency Board had to came up an additional $427,500.  Et cetera.   

Bear in mind that the infected acreage noted below doesn't include all of the surrounding land--public and private--that must be treated in the effort to eradicate the fungus. 

The Oregon Forestry Department has found 41 new Sudden Oak Death (SOD) infestations in Curry County this year, totaling 14 acres, said a report received by the Curry County Biomass Working Group at its meeting Thursday.

“The sites all are small with very few infected trees,” said the report written by Forest Pathologist Alan Kanaskie.

...

Other trees besides tan oak that are killed by the disease include black oaks, liveoaks, and possibly madrones, but not white oaks. The disease also affects some plants such as rhododendron, and it causes a leaf blight on the Oregon myrtlewood.

There's a long list of trees and shrubs that SOD infects but doesn't kill, including the redwood.  That's why the following, reported almost a month ago, was rather alarming.

A tanoak tree located on the Redwood Nature Trail, east of Brookings, has recently tested positively for the plant disease.

To reduce the risk of spreading the pathogen, the U.S. Forest Service immediately closed the trail and will be conducting more extensive surveys in the area to monitor if additional vegetation may be infected.

If any of those redwoods should become infected, will forestry officials kill them as they do other infected plants because they can be contagious?  If not, the groves will become a permanent reservoir for the disease. 

Fortunately, infected redwoods don't seem to be particularly efficient at helping SOD to spread.  The research at this link suggests that because redwoods aren't severely impacted by the fungus but some of their competition is, the presence of SOD could improve the survivability of redwoods.  That's of no solace to--for instance--the animals dependent upon the heavy acorn production of tanoaks.

And if SOD ever gets a foothold in the Rogue or especially the Willamette Valley, it will could kill huge numbers of trees, ravage parts of the nursery industry, etc.

Stimulus Money for an Unhealthy Forest

For several years now, the Oregon Departments of Forestry and Agriculture have been working together to eradicate--well, limit the spread--of sudden oak death fungus in Curry County.  For a spell last year, these efforts stopped because the agencies ran out of money (previous blog here).  Fortunately, the Legislative Emergency Board came up with $427,500 to allow the work to continue. 

More work needs to be done this summer, but there's no state money to do it.  However, it looks like some federal stimulus money is on the way. 

The Oregon Department of Forestry hopes for $2.7 million in federal stimulus money to slow the spread of Sudden Oak Death, Forest Pathologist Alan Kanaskie said at a public meeting Thursday.

“We’re told we’ll get $2.7 million, but we haven’t got it yet,” Kanaskie said. “If we can reduce the host species in the north part of the quarantine area, we can slow the spreading.”

...

When the stimulus money is approved, Kanaskie said each $1 million would be enough for 22 full-time workers to remove host plants.

Unemployment in Curry County is currently 14 percent. 

He said the best way to contain the spread is to take host plants out in a 3-mile wide path at the edge of the quarantine area, which remains the same as last year.

The eight new sites were found in a recent aerial survey and there will be another one in about a week.

“We’ll have a bigger one in July,” Kanaskie said.

Since 2001, when Sudden Oak Death was first found in the Brookings area, about $4 million has been used to slow the spread of the tree disease, including $1.35 million from the state.

Thus, $2.7 million should certainly allow local officials to take aggressive action this year.  Wonder if anybody will have money to spend next year.

A Limited Arsenal

Yesterday, the Curry Pilot had an article updating the status of the efforts to eradicate--or at least control--sudden oak death fungus in the county.  The disease is continuing to spread, though fortunately here in Oregon it's still limited to Curry County.  There, SOD has been killing primarily tanoaks.  However, it also infects a number of other native species and garden plants, through which it spreads.  

The Oregon Department of Forestry found 63 new sites in Curry County infected with Sudden Oak Death during 2008, including seven new infested sites located in a flyover in October.

Those sites discovered last year added up to 25 acres infected and combined into 50 treatment areas, said Forest Pathologist Alan Kanaskie.

"Most of these areas have been treated or treatments are in progress," he said. "We still have seven sites that are completely untreated because of a temporary lack of funds, and we have some cleanup on unfinished sites from last year. We expect to resume some level of treatment within a month."

That temporary lack of funds pertains to the ODF running out of money for SOD eradication last summer (previous blog here).  The Legislature's Emergency Board came through with an extra $427,500.  But, there's been something else that has been hampering eradication.   

"We're able to apply herbicide almost everywhere, except on the BLM land," Savona said.

The BLM has an injunction against using some herbicides on its land.

Switching links...

In 1984, the BLM in Oregon was prohibited from herbicide use by the U.S. District Court of the District of Oregon. In 1987, the BLM released a Final Supplement to the Northwest Area Noxious Weed Control Program Environmental Impact Statement (FSEIS) and submitted it to the U.S. District Court of the District of Oregon. In the FSEIS, the BLM proposed resuming the use of the herbicide active ingredients dicamba, glyphosate, picloram and 2,4-D and provided Worst Case Analyses for these herbicides. The U.S. District Court found that the FSEIS fulfilled National Environmental Policy Act (NEPA) requirements and partially dissolved the injunction, permitting Oregon BLM to use the four herbicide active ingredients analyzed in the FSEIS. These herbicides can only be used on weeds officially designated on county, state and federal noxious weed lists.

...

Herbicide use on BLM lands in Oregon is currently limited to treating listed noxious weeds. The EIS will propose to add herbicides to the list of management tools available for the treatment of forest pests and diseases such as Sudden Oak Death. While there is no herbicide available that targets Sudden Oak Death, treatments usually consist of controlling the pathogen by killing the host species in affected areas to prevent the spread to other areas.

What EIS is the latter paragraph referencing?  Again switching links...

The Bureau of Land Management (BLM) is developing a Vegetation Treatments Using Herbicides on BLM Lands in Oregon Environmental Impact Statement (EIS). Noxious weeds, invasive plants, and other weeds infest millions of acres in Oregon. To address this issue, the EIS will analyze the effects of herbicide use on Oregon BLM lands as one of the many tools to control noxious weeds, invasive plants, and other weeds and achieve landscape health objectives. The EIS will only address the effects of updating the list of available herbicides for use in Oregon. Currently, Oregon BLM uses only four of the 18 herbicides approved for use on BLM lands nationally as identified in the Vegetation Treatment Using Herbicides on Bureau of Land Management Lands in 17 Western States EIS. The EIS will not evaluate the use of herbicides for commercial timber enhancement or livestock forage production.

The scoping period ended last July, the draft EIS should be available in May, and the Record of Decision is scheduled to be published in March of 2010.  No doubt lawsuits will preclude that.

A Harbinger for Southern Oregon?

Sudden oak death fungus (SOD), the same non-native pathogen that is spreading in neighboring Curry County (most recent blog here), has been ravaging parts of the Coast Range in California.  The standing dead tanoaks, coast live oaks, and California black oaks are providing nicely-cured fuel for the Basin Complex Fire, which has now burned over 77,000 acres and is just 18 percent contained.  From this link...

Although the massive oak die-off has swept through forests lining California's central and northern coasts, the Big Sur area is especially hard hit, said UC Davis plant pathology professor David Rizzo, an expert in the disease.

"It's reached its apex in Big Sur," Rizzo said Sunday. "The thing with Big Sur that's making it so bad is that's probably the worst place in the state for dead trees."

He estimates that 1 million dead oak trees can be found in a 200,000-acre sweep of Big Sur forest that he has studied for the last three years in a federally funded study of sudden oak death. That number was confirmed Sunday by retired U.S. Forest Service forester John Kelly, who conducted aerial surveys of dead trees in area forests and is now advising Basin Complex fire managers.

While SOD only kills a few types of trees, it can infect and be spread by a wide variety of trees and bushes.  No doubt the fire helping to destroy some of the carriers in the forests there...but only some of them.  

"You look in some of these canyons, and you'll see 70%, 80% of tanoaks are dead," said Rizzo, who expressed concern about the Palo Colorado Canyon area that fire crews have been defending.

U.S. Forest Service forest ecologist Lloyd Williams said Sunday that the dead oaks were most prevalent on the fire's western slope, representing about one-third of the 72,000-acre Basin Complex fire area.

"They're added fuel to the fire," said Williams, the botanist for Los Padres National Forest. "The intensity is much hotter. The fire burns hotter. It spreads faster." Since many of the dead oaks are still standing, he said "The fire can go up the tree and burning embers can spread."

Fortunately at the end of last month, our legislature's Emergency Board came through with extra money to battle SOD in Curry County.

The $427,500 in general funds the E-Board allocated for sudden oak death eradication came in spite of a lack of support from the Department of Administrative Services.

"We're very happy to see the state step up on that piece," said Katie Fast, director of government affairs for the Oregon Farm Bureau. "It was not recommended by DAS, and there are challenges on getting the federal funds to make sure that project continues."

The Oregon Department of Forestry is using the state money to keep its eradication program operating while it looks for new federal funding.

The U.S. Forest Service in the past has helped the state pay for its SOD eradication program, but those funds have dried up, ODF spokesman Dan Postrel said.

What the heck is up with our DAS and USFS?  We sure don't want to see what SOD could do to the forests and agriculture here in the Rogue Valley...or up say in the Willamette Valley, where it could potentially wreak havoc on the nursery industry.

Encouraging the Spread of Sudden Oak Death Fungus (Updated)

Sudden oak death (SOD) fungus has ravaged some of the forests on California's coast range, killing enormous numbers of oaks and tanoaks.  SOD has also been slowly spreading in nearby Curry County (most recent blog here).  What has the state been doing about it?  Until recently, not enough...and now the answer is nothing.

Curry County commissioners have written the co-chairs of the Legislative Emergency Board pleading for more money for the Oregon Department of Forestry to continue to work to eradicate sudden oak death (SOD) in the county's trees.

"They have quit all work because funding is stopped," Commission Chair Georgia Nowlin said.

...

The Oregon Department of Forestry (ODF) and Oregon Department of Agriculture (ODA) have been working together since Sudden Oak Death was first discovered near Brookings in 2001. Because the pathogen is thought to travel through warm, wet air, coastal towns such as Brookings are an easy target – and make it difficult even for experts to eradicate the disease.

So far, most new infestations, including the five most recently-infested sites, occurred because of delayed detection, inadequate treatment area size, time elapsed between detection and eradication, and actual spreading during the removal efforts.

Here's a lengthy listing of species succeptible to SOD infection.  Lord knows how many trees and bushes SOD could weaken or kill if it made its way to the Rogue Valley, much less the Willamette Valley.  Douglas County is supposed to be writing the state on the unacceptable lack of funding, and JoCo should do the same.  Here's the letter that Curry County will send to Senator Courtney and Representative Merkley, the Emergency Board Co-Chairs.

"Healthy forests are essential to the health of Curry County," the letter says. "Our forests are now threatened by a nonnative pathogen: sudden oak death. Phytophthora ramorum, the cause of sudden oak death (SOD) kills tanoak, California black oak, coast live oak trees, and damages many other trees and plants in western forests and horticultural nurseries. If allowed to spread unchecked in Oregon and northern California, it will seriously affect our forests and local economies. The resulting market access impacts will disrupt domestic and international trade for many of our forest and agricultural commodities. Already, 160 square miles of Curry County are quarantined, affecting the sales and export of those products in that area.

"The Departments of Forestry and Agriculture eradication efforts have demonstrated success on many infected sites. We have learned through the current eradication work the factors that have led to the continued slow spread of SOD. Being fully successful with SOD eradication now depends upon enhancing our early detection and becoming more aggressive in our eradication programs.

"The Oregon Department of Forestry is seeking $427,500 of additional state funds which will allow them to continue with current eradication efforts through September of this year. These funds will provide Oregon a bridge to the additional federal eradication funds that are needed.

"Thank you for your consideration of the Department's request. Your positive response to this emergency request is appreciated as we work with the Department and others in obtaining additional federal resources to continue and enhance Oregon's eradication efforts."

I hope Merkley remembers that one of the most important things a candidate can do while campaigning for a new job is excel at one's existing job.

One last note that sure hasn't gotten much press here in Oregon...

P. ramorum has been detected in three OR nurseries and one landscape site in 2008. At all sites, P. ramorum was initially detected on infected Rhododendron. During delimitation surveys in the nurseries, additional positives were found in the soil and potting media at one nursery and in the cull pile, soil beneath an infected block, and in a block of Arctostaphylos uva-ursi at the second nursery. No additional positives have been found in the third nursery, although soil and media samples are still pending. The delimitation surveys for the landscape site are underway. The infected plant at the landscape site was purchased from a positive Oregon nursery earlier this year.

Arctostaphylos uva-ursi is a native manzanita species we call kinnikinnick or bearberry. 

Yes, it's possible that even if the state gives its best effort at fighting SOD, it will turn out to be a losing battle.  However, it's certainly a battle that needs to be fought. 

UPDATE:  The Emergency Board did provide the $427K...see end of post here. 

Getting More Serious About SOD in Curry County

Sudden oak death (SOD) fungus continues to expand its range in Curry County (most recent blog here).  The state finally seems to realize that if it doesn't seriously step up its efforts to control, much less eradicate SOD, the pathogen will eventually spread into parts of the state where it can do a lot more harm.   

"We've changed our treatments, are cutting more infected patches – but the last two years have been really bad," ODF Forest Pathologist Alan Kanaskie said. "We know how to chase it down and find it, but (the disease) is always one step ahead of us. If we keep doing this the way we have been, we'll be doing it forever – or until the money runs out."

So far, most new infestations, including the five most recently-infested sites, occurred because of delayed detection, inadequate treatment area size, time elapsed between detection and eradication, and actual spreading during the removal efforts.

In response to state and industry outcries to get rid of Sudden Oak Death once and for all, the ODA and ODF are taking new, more drastic measures – and realizing they can't do it strictly from their offices in Salem. So, they are seeking local input.

As if any of the measures taken in what's now considered Phase I of the response have been drastic.

ODA and ODF invited local residents and businesses to a workshop to discuss Phase II, a more aggressive approach.

1) An improved early detection system with increased stream baiting – which requires hanging a mesh bag of rhododendron leaves in a stream to help determine the presence of P. ramorum in the water. Aerial surveys will cover larger areas, and ground surveys will be conducted year round.

Suggestions from attendees included taking volumetric air samples as well as holding regular workshops on how residents and local industries can detect Sudden Oak Death themselves.

2) A reliably-funded rapid response system with crews who can be deployed on short notice to infested sites within days of Sudden Oak Death detection.

Most people at the workshop stressed the importance of contracting local crews so the response time to nearby infested sites would be adequate.

3) An extended treatment area size that includes a 600-foot buffer zone, and continued aggressive eradication attempts with faster response time.

Because the extended buffer zone will have a larger impact on the livelihood of landowners, a few people suggested treating tanoaks on the edge of the perimeter with herbicide, rather than the normal cut-and-burn tactic.

A big buffer zone is essential because there are so many species which can be infected by and act as a reservoir for the fungus.  If you chintz on the effort and leave a little bit of the cancer... 

4) A risk modeling project to predict where the disease might spread next, and removal of tanoak on those susceptible landscapes. This may include an incentive program to landowners to remove tanoaks from their property, and an increased market for tanoak.

Most people at the workshop agreed that, if healthy tanoaks were going to be cut down, yet stay within the quarantine zone, different markets for tanoak should be promoted.

5) New preventive treatments using the fungicide phosphonate to inject or spray on the trunk of infected trees.

Both ODA and ODF officials, along with attendees, agreed that continued education about Sudden Oak Death and alternative treatments was necessary.

6) Continued research on pathogen spread, risk mapping, alternative treatments and genetic resistance of some tanoak species to P. ramorum. Local residents also suggested more in-depth research on the effectiveness of phosphonate.

7) An integrated and coordinated approach between experts, researchers, businesses and landowners on how to stop Sudden Oak Death once and for all.

This link provides some information on the use of Agri-Fos, the trade name of the phosphonate mentioned above.

The key issue everyone at the workshop pushed was the need for a local contact who can coordinate workshops, discussions and help residents and businesses in the area with problems they are facing due to Sudden Oak Death and the revamped eradication efforts.

"If we're really going to get this off the ground and find a way ... we need to do it with someone here," said Becky Crockett, a concerned Portland resident whose family owns land near Brookings.

In response to the concern, Osterbauer and Kanaskie are looking to fill an ODF position in Brookings, where the official would act as liaison between ODF Salem offices and Brookings-Harbor.

ODF should have done that awhile back.

Sudden Oak Death Fungus Spreads in Curry County

The Oregon Department of Agriculture has struggled with Curry County's outbreak of sudden oak death (SOD) fungus (previous blog here).  The following chart shows that the ODA has had to grow the quarantine area multiple times...and it's now up to 26 square miles. 

Counting the number of new SOD trees is nice, but the fungus can infect a number of trees and shrubs, only some of which it kills (like tanoaks and coast live oaks).  Many common species like azaleas, rhododendrons, and evergreen huckleberries suffer damage but usually survive to provide a natural reservoir for the fungus.  The ODA has obviously never gotten the reservoir under control.   

This past August, the ODA found 14 infected trees in Azalea Park, which is in Brookings and thus outside of the quarantine area (previous blog here).  That former state park, which has a number of tanoaks, is famous for its rhodies and azaleas...footstomp.  Nearly three months later...

The state wants to expand the current Sudden Oak Death quarantine area around Brookings to 166 square miles in its ongoing attack on a disease that has already infected trees at Azalea Park and nearby private property.

The expansion, proposed by the Oregon Department of Agriculture (ODA), would impact two local lumber mills, about a dozen nurseries, five state parks and additional private landowners.

"The reason we are proposing such a large expansion, is because two of the most recent infested sites we found are at least three miles outside the existing quarantined area, meaning the pathogen is able to jump three miles from site to site," Nancy Osterbauer, plant health program manager for the ODA, said.

"We need to actively eradicate this disease before it spreads further, and that's why we are proposing to extend the quarantined area."

Since SOD readily spreads via rain and wind, waiting on this decision until the rainy season wasn't exactly a brilliant move.   

In an effort to stop the spread of the tree-killing pathogen Phytophthora ramorum (P. ramorum)--responsible for for infecting more than 100 different plant species, specifically tanoak trees--the ODA is proposing to expand the existing 26-square-mile quarantine area directly outside Brookings to cover 12 miles inland from Pistol River down to the California State border.

...

In an attempt to halt the spread of the disease, the ODA established a quarantine boundary and the Oregon Department of Forestry (ODF) began cutting and burning infected tanoaks. Even with the removal of more than 150 tanoak trees in Azalea Park in the past few weeks, the pathogen continues to gain a foothold in Curry County.

According to Dan Hilburn, ODA state plant regulatory official, the proposed quarantine site will restrict people and business from removing certain tree species out of the area, while the infested sites will be completely off limits.

"The quarantined zone will include sites where the pathogen has not been found, so the entire area won't be treated – just the five newly discovered sites," Hilburn said. "In those sites, we have already started cutting and burning host material, which includes tanoaks, less susceptible trees like myrtle, and bushes such as huckleberry and rhododendron. Within uninfected areas, people just need to be careful not to remove tanoak and other host material out of the quarantined area."

Just treating the areas discovered to be infected has certainly been a failed strategy thus far.  Thus, we have no reason to expect that it will work this time.  More drastic measures are needed, but the ODF still isn't being very aggressive. 

"We needed to accommodate the increasing number of infested trees and sites that were discovered over the years," (ODF forest pathologist) Kanaskie said. "But after the Oregon Department of Forestry found five new sudden oak death-infested sites in 2007, we realized we need to expand the quarantined area to include everything and restrict the movement of the pathogen."

Osterbauer said the extension will include a 3-mile buffer of forest land between the infested sites and the quarantine boundary line--sort of like a safety net.

According to Kanaskie, if the proposed quarantined zone is approved by the ODA hearings officer, anyone who uses the forest--for pleasure or for business--will be affected.

"If you are a timber company and want to harvest tanoak or myrtle within the quarantined area, you can't ship it outside the boundary line," Kanaskie said. "For instance, South Coast Lumber in Brookings has been affected since infested sites have been discovered on their land, and the quarantined area will restrict their movement of lumber. But they are being very cooperative, and in most cases, we are contracting different companies to help them and others with the eradication effort."

That's it, a buffer zone?  I'm underwhelmed.   

According to Hilburn, all private landowners who own property within the five new infested sites, have already been notified by mail that the ODF found diseased trees on their land.

"We are working with the Oregon Department of Forestry to eradicate every infected tree, and most of the removal has not been done at the owner's expense," Hilburn said. "Thousands and thousands of trees have already been killed by sudden oak death in California – that's why we can't turn our backs on this, or else the pathogen will spread like ripples in a pond."

Osterbauer said the worst-case scenario would be if Curry County ended up with a situation similar to Humboldt County, Calif. where approximately 5,000 acres of forest land is infected with sudden oak death.

"The quarantined area is onerous for land owners, but the impact for the region is tremendously worse if we don't eradicate this disease," she said. "If we don't start showing some improvement and go through with this expansion, the United States Department of Agriculture (USDA) can quarantine the entire county–-which would affect a lot more people."

Humboldt County is nowhere near the worst case.  Try more than a million trees killed between Mendocino and Monterrey in SOD's recent resurgence there.

At least the ODF's efforts have kept the spread of SOD slow.  But if this is all the ODF is going to do, they ought to stop using the word eradication. 

More Sudden Oak Death in Curry County

Curry County has been struggling with sudden oak death (SOD) fungus (previous blog here).  Sadly, the following shows that the fungus there is still not contained.

City officials said Monday the Oregon Department of Agriculture (ODA) notified them late last week of the 14 diseased trees and ordered an attempt be made to eradicate the disease from the area.

In a letter dated Aug. 8 to the city from ODA Plant Division Administrator Daniel Hilburn, the department called for the city's cooperation to prevent the disease from spreading to other vegetation.

"We believe we have caught the disease in the first stages of establishment," Hilburn wrote. "Thus, this is our best chance to halt the spread of this dangerous pathogen." 

"Forestry officials are proposing to inject all infected trees and all tanoak trees with a herbicide and then cut and burn the trees on site this fall," Milliman said.

Azalea Park was a state park until 1993, when the state--which considered the park a burden--turned it over to the City of Brookings.  The existing SOD quarantine area (map at p. 4 of this pdf) begins a short distance north of the park. 

Azalea Park contains five types of endangered native azaleas and over 400 rhododendrons; both types of plants are susceptible to SOD. While the fungus is deadly to some species--like tanoaks, it typically doesn't kill rhodies and azaleas, instead causing leaf spots and twig dieback.  The infected plants act as reservoirs of the disease, helping it to spread.  In fact, understory rhododendrons are key to the spread of SOD in English forests.

The city is torn between concerns about erosion near the North bank and air quality from a possible burn and concerns about the disease spreading to other areas of the park, he said.

"That's a difficult balance we haven't sorted out yet," he said. "If this is a truly significant threat to the azaleas and rhododendrons, I think it's appropriate to take action to prevent that."

...

The 14 infected trees would not be the only ones to be cut, according to the ODF. In his letter, Hilburn said his department would require the city to cut and burn the infected area and a buffer zone to be set by the ODF and ODA.

The work would be done by an ODF crew, Hilburn said.

This work needs to occur quickly before the rains set in; they help spread SOD. 

Frank Burris, watershed extension agent of the Oregon State University Extension Service in Gold Beach, said five of eight sites where the disease was initially found have been successfully eradicated, but Azalea Park's trees show there is still work to be done.

"It means it's still moving," Burris said of the disease. "We don't fully understand how to stop it. Realistically, (state agencies) are doing a pretty good job of containing it."

Milliman said a public meeting to discuss and analyze the ODF findings will be held sometime in early September.

"We think the community needs to be fully informed on what (ODF's) findings are," and given answers about eradicating the disease from the park, he said. "It's a sensitive area. Some folks out there are concerned.

It's easy to unwittingly spread this fungus--and not just via the nursery trade.  The public needs to be fully aware of where SOD is and the danger it presents.  And that means no more false bravado by public officials about having the fungus contained. 

Denser Forests, More Disease

Sudden oak death (SOD) fungus is an invasive species that has established itself in parts of California and Curry County OR (range map here).  It preys upon a number of common bushes and trees and is deadly to a few of them, including oaks, the tanoak (which isn't a true oak), madrone, and viburnums (previous blogs here & here).  Part of the reason that SOD thrives and spreads so readily in the Coast Range is that parts of the forests there are changing and becoming more suitable to the fungus.   

A recent article published by Meentemeyer and colleagues in the Journal of Ecology showed that “pathogen inoculum load” (the actual amount of infectious pathogen present) is greater in forests with high landscape connectivity and high abundance of host species. In a follow-up study forthcoming in Ecological Applications, Meentemeyer and his colleagues report that years of fire suppression and other land-use practices have altered structure and composition of forests in way that may facilitate spread of the disease. California’s oak woodlands have grown larger and denser over the past six decades. Counter-intuitively, this has made them more susceptible to being wiped out by the rapid onset of sudden oak death.

”More connected forests have more disease,” said Meentemeyer. “Smaller and more isolated forests have less disease. Being smaller and more isolated doesn’t necessarily prevent disease, but it occurs at smaller levels in those areas.”

Plus when there are more and larger trees trying to survive in an area, there is more competition for limited resources, which puts the trees under increased stress.  In other parts of the U.S., pine bark beetles are certainly taking advantage of this dynamic (example here). 

This finding connects with research presented in the article forthcoming in Ecological Applications. Meentemeyer and colleagues discuss findings that further suggest humans have been causing landscape changes that are encouraging the spread of the disease. The study examines detailed aerial photography records for an area of northern California and shows that oak woodlands have increased in area by 25% over a 58-year period, while grasslands and chaparral shrublands (non-host vegetation types) have both significantly decreased.

The researchers suspect that the reason larger and denser patches of forest encourage the spread of the disease involves the role played by another California woodland tree—Bay laurel. Bay laurel is the primary carrier for the disease, since it acquires a non-lethal but highly contagious leaf infection. Bay laurel seems to be increasing in abundance in the changing forests and to make matters worse denser forests create cooler and moister understory microclimates that encourage the spread of the bay laurel leaf infection, which in turn can lead to the fatal infection of the oaks.

The effect of larger, cooler forests “explained significant variation in infection level of P. ramorum,” the article argues. “We conclude that enlargement of woodlands and closure of canopy gaps, likely due to years of fire suppression, facilitated the establishment of P. ramorum by increasing contagion of hosts and enhancing forest microclimate conditions.”

How do we get the forests back closer to the way they used to be?  Not by doing nothing.  For millennia, Native Americans managed vast swaths of our forestlands with regular fires, shaping the landscape more to their advantage.  Those fires reduced fuel levels, helping to prevent most of the destructive megafires that our forests suffer today.  How do we reduce fuel levels today?  Too often by pretending that megafires are natural and healthy for our forests.  It's charred common ground for a number of our federal forest managers and environmentalists.   

Unhealthy forest management may be encouraging the spread of the disease, but it is perhaps not the only way humans are furthering sudden oak death’s deadly march. In other research using Geographic Information System analysis, Meentemeyer and his colleague Hall Cushman at Sonoma State University found evidence that humans may be spreading the disease directly through the unintentional transportation of small amounts of infected soil.

“There is some compelling evidence that humans could be moving the disease in infested soil,” Meentemeyer said. “We have found evidence for human involvement at three different scales of analysis. First of all, the pathogen is much more likely to occur along hiking and biking trails, where humans travel. Second, using some of our landscape and regional data, we have shown that highly visited state and county parks have more disease than private ranches and lands that have very limited visitation.

Gee, thank goodness Californians rank near the bottom of the nation in enjoying outdoor activities (recent blog here).

“We have also found on an even broader scale across the state of California that forests surrounded by high human population densities are more likely to be infected. In this analysis, we carefully controlled for the effect of climate and other environmental factors known to cause disease.”

But, is this because there are more Californians nearby to visit the forests they surround?  Or because the pollutants from the population centers make the forests more vulnerable to SOD?  Or maybe is it a simply a coincidence of geography?  Researchers don't know yet.  There's a lot more to learn about this nasty fungus.

Fighting Sudden Oak Death Fungus with Fire

Sudden oak death fungus (SOD), an introduced species, has proven difficult to eradicate (recent blog here).  It only kills a few of the species it attacks, with the resulting bark cankers essentially girdling the hosts in one to several years.  Other species suffer only a foliar blight which is not fatal...the victims serve as a reservoir for the fungus.  There is no cure.  The only somewhat effective way to battle SOD in the wild is to cut down the infected trees and bushes, then burn them.  So, forestry official have decided to experiment with a controlled burn to see if that helps. 

Forestry experts on Tuesday were trying to wipe out an infestation of a persistent disease that has killed thousands of acres of California's magnificent oaks to the south by cooking it to death. The experiment aims to find out if sudden oak death can be eradicated or at least checked from becoming an epidemic in Humboldt County.

Last year, workers cut hundreds of California bay laurel and tan oak trees -- primary hosts in the area -- from a 50-acre stand in Humboldt Redwoods State Park. Twenty-five of those acres were to be burned on Tuesday and Wednesday to see if the pathogen, Phytopthera ramorum, crops up like it did after being mechanically treated.

”We're curious to know if adding fire will make a difference,” said Yana Valachovic, University of California Cooperative Extension forest advisor.

...

Trees in this area -- even young tan oaks sprouting from cut trees -- were already cankered with sudden oak death. That's especially true where they are shaded by bay trees, which drop spores onto the oaks.

Tanoaks, which are very susceptible to SOD, aren't a true oak but part of a genus that's a link between oaks and chestnuts.  These trees, which can thrive in either sun or shade, produce acorns (which the squirrels and Steller's jays love to dine upon around here) but have flowers similar to those of chestnuts.

If tanoaks are burned or cut, many readily sprout from numerous buds just below the soil line.  Occasionally, parts of the massive root systems can emerge from the soil and form burls with buds that will also sprout.  This helps the tanoak to be a species which can take advantage of disturbances.  However, older tanoaks don't heal as well after fires, with the subsequent decay taking a toll and making them more susceptible to fire and weather damage.

This is a relatively isolated hot spot. There are some stands in the county where 50 percent of the oaks are dead, Valachovic said. It's precisely that isolation that made this a good spot to fight sudden oak death, and Valachovic said there's been worldwide interest in the experiment.

The effort is to find a treatment that is effective, socially acceptable and economically viable, she said.

...

Over the next few years, experts can watch to see if the fire fully consumed leaf litter and infected trees, and with it eliminated the disease from the soil. It's also part of reintroducing fire into an area with a long history of wildfires and the American Indian practice of burning, which has been replaced by a policy of suppressing fires for decades.

In that area, lack of fire has allowed Douglas firs to encroach into grasslands.  Officials are hoping to reclaim/restore some of the prairies.  The article noted that the fire would also provide an opportunity to train CDF and inmate firefighters.

I hope the fire helps against SOD, but I definitely don't see a silver bullet here.