(helicopter engine whirring) - [Narrator] Forest pathologists have their hands full tracking the many threats to Oregon's vast forest lands.

But a helicopter can help.

From the air, Mike McWilliams gets a front row seat to trouble brewing in the forest of the southwest coast.

- [Mike] Bear damage out there, looking on those dead firs.

- [Narrator] Scattered among sprawling acres of timber are Douglas fir saplings shredded by bears, pines plagued by bark beetles, and meadows infected with Scotch broom.

But the signature red of a single dead tanoak is a beacon of real danger, a sign that these forests could be in big trouble.

- [Mike] See how it just stands out there amongst all the others?

It just pops out at you.

- [Narrator] It's the calling card of a killer, a mysterious pathogen called Phytophthora ramorum.

Most people call it sudden oak death, or SOD, because it kills tanoaks within days.

But this microbial pest kills far more than just oak trees.

At risk are iconic Oregon plants like rhododendron, evergreen huckleberry, azalea, and 30 other native species.

If sudden oak death takes hold, Oregon's forest could end up looking like an herbicide-treated timber plantation.

- [Mike] This is exactly what a hillside full of sudden oak death would look like, lots of dead trees.

- [Narrator] Mike is Oregon's sudden oak death early warning system.

And yet every time he spots a tree that turns up infected, more trees have to die.

(chainsaw whirring) (tree thuds) Slash and burn crews destroy everything within sight of a single infected tree.

Nothing is saved.

The risk of spreading the disease is too great.

(tree thuds) - [Kevin] You don't want to see things like this, but it's one of those situations where if we didn't do what we are doing, it would be much, much worse.

- [Narrator] Kevin Nelson has led dozens of operations like this since sudden oak death was first discovered in Oregon in 2001.

- Basically, we came in to check out some helicopter trees that our guy from the air spotted right over here.

And when we came in, the tree itself was dead, had no live foliage on it except live sprouts at the base.

So this is a really classic sudden oak death symptom on a leaf, the dead vein creeping up the center there.

- Should we take them down one at a time or do you take the whole group down?

- [Narrator] Forest pathologist Alan Kanaskie can deploy eradication teams anywhere on state and even private land at the first sign of infection.

So far, it's worked.

The disease remains contained in the wild to a 22-square-mile quarantine area near Brookings.

- The question is like, how many trees do you have to find before you take an action like this?

The answer is one leaf on a tree.

We're going to cut out about an acre or two right here and then we'll go up the road, and that side we'll cut out about two acres.

- [Narrator] Behind the chainsaws and flamethrowers are ecologists and pathologists from the Forest Service, Oregon Department of Forestry, Oregon Department of Agriculture, and Oregon State University.

It's a rare joint effort, worded by the consensus that only extreme measures can save our forest from a full-scale invasion.

(tree thuds) - You know, thinking the idea coming north from California, we are basically on, you know, the front line, the front edge, as it's creeping its way into Oregon right here specifically.

So, yeah, the sooner we stop it here, the better it's going to be for everybody.

(chainsaws whirring) - [Narrator] Sudden oak death first laid seeds to California in the late 1990s.

Scientists were caught off guard, and millions of coast live oak and tanoak trees died in places like Sonoma and Marin Counties, and more are dying every day.

(chainsaw whirring) Oregon got the message and declared that even one infected tree within our borders is reason to fire up the chainsaws.

- [Kevin] Every time a new tree is infected, it just, there's thousands and thousands of leaves, all with infectious material on them that can blow into the creeks, they can blow into the wind, they can blow to other hillsides.

So, every time it spreads to one more tree, you're just compounding the problem a hundred times.

Once we get a positive from the lab, we know the disease is in the area and we have to stop it.

(fire crackling) - [Narrator] The detectives behind the scenes are pathologists Wendy Sutton and Everett Hansen of Oregon State University.

They examine bark and leaf samples sent in from the field for signs of Phytophthora ramorum, the pathogen that causes sudden oak death.

(machine whirring) - [Everett] These came out of the stream that was sampled last week, and these are the sorts of symptoms that we're looking for.

Very neat symptoms of infection on the rhododendron leaves.

- [Narrator] Lab testing is the critical step between spotting a dead tree and calling in the cutting crews.

Identifying this pathogen is easy, but everything else is a mystery.

- This is what we see in culture growing out from one of those pieces of leaf.

What we just saw there was the sporangium releasing its zoospores.

They'll settle down and germinate on the leaf and penetrate and start killing leaf tissue.

This is new stuff.

New fungus in the woods, new to science, new to the lab.

We don't understand what's going on here.

It's part of what we're doing.

We're trying to find the biological explanations for these things that are going on.

People are going to go out and cut down trees and burn things up, so we want to make sure we're right.

- [Narrator] Phytophthora ramorum is one of dozens of Phytophthoras in the wild.

Many are benign, and a few cause limited damage, but the sudden oak death variety is particularly vicious.

It's an invasive species, no one knows where it came from, and it travels by water, be it rain, river, or on the muddy soles of boots.

In other words, conditions for an Oregon epidemic are perfect.

- [Everett] It's not just a few brown leaves.

It kills tanoak trees, it kills coast live oak trees, it kills madrone trees, but it also causes disease on rhododendrons, evergreen huckleberry.

It's hard to imagine Honeyman State Park, for example, without its wild rhododendrons.

What would Florence do in the spring when they have their Rhododendron Festival if all the rhododendrons were gone?

- [Narrator] The appeal of a beautiful flowering rhododendron isn't lost on the rest of the world.

The trade in these flowering plants is big business for Oregon nurseries, yet nurseries too face the ravages of sudden oak death.

A nursery quarantine is now in effect, and every grower shipping plants faces inspection.

- [Nurseryman] We have about 5,000 different varieties of plants, rhododendrons being our specialty.

- [Narrator] Inspectors paid a visit to this Willamette Valley nurseryman last year.

He asked that we not mention his name.

Many retailers are afraid to buy from nurseries that test positive.

- The end result was that they found it on three different plants or so in different areas.

They have to go so many feet from where that plant is and destroy everything that's there, that host material.

Well, we lost about 1500 plants, somewhere in that neighborhood.

And with a retail value of an excess of $10 a piece, probably more like 20 in many cases, well, it was certainly not a very happy situation.

- [Narrator] The inspections are inconvenient and intrusive, and they're made worse by the fact that growers aren't paid for confiscated plants.

Losses here totaled almost $20,000, yet it's unclear why this nursery was contaminated while others weren't.

I'm told that it's all contained down in Southern Oregon.

How did you get it?

- Good question.

We have, they don't really even seem to know how it spreads, supposedly, on nursery stock, but what we found it on came from a local area here.

So, how did it move?

We don't know.

- [Narrator] There is still debate about whether sudden oak death originated in a nursery or in the wild.

Anyone working on this issue will tell you it no longer matters.

What matters is containment, yet the situation in the nurseries is complicated by free trade.

- This stuff in here is all waiting to be shipped.

Two-thirds of everything is shipped out to other parts of the country, and world for that matter.

- [Narrator] Nursery plants are Oregon's largest agricultural crop and generate sales of hundreds of millions of dollars yearly.

If infected plants escape inspection, sudden oak death could spread around the globe.

This grower, for one, believes that's exactly what's in store.

- I think they'll finally have it in so many places, it'll be like other diseases that we tried to stop but are still here.

- [Interviewer] That'll be harsh news for these guys who are spending all their time down there cutting and burning.

- Yeah.

Absolutely.

- [Narrator] For their part, foresters are convinced that without intervention, a catastrophe will ensue.

It's their mission to stop that from happening.

- [Kevin] 29 degrees, 0.02 miles.

And the tree should be just a very few feet that direction.

- [Narrator] Somewhere out here is a dead tree that was located by helicopter.

And first, everything looks good.

But then Ellen Goheen, with the Forest Service, spots a problem.

- This particular sprout is from this dead tanoak, and it's showing very good symptoms of infection by Phytophthora ramorum.

- [Forester] I can see if we get symptoms.

- [Narrator] As Mike and Kevin take samples from the suspect tree, the mood darkens.

- If this tree is infected, these dead patches will spread out and eventually grow together and girdle the tree.

So there'll be no live bark on this tree.

- [Narrator] Mike's team decides that everything within sight of this tree will be slashed and burned.

- You know, it doesn't feel good to know that all these trees are going to have to come down, but the disease is here, we already know that these trees are going to die, and it would be negligent for us to leave them here.

- [Mike] See this black line?

That's a great symptom, and we'll sample that.

- [Narrator] Oregonians have been largely unaware of this war to save the forest.

That could change if the disease escapes and marches north.

- Is this a beautiful Arbor Day or what?

- [Narrator] Portland has been named Tree City USA many years running.

It's a legacy at risk.

- Now therefore, I, Tom Potter, mayor of the city of Portland, do hereby proclaim the month of April to be Arbor Month and urge all citizens to plant and care for trees in honor of this rejuvenating occasion.

- [Narrator] If sudden oak death strikes Portland, the effects would be felt immediately.

Sudden oak death kills some trees, just damages others.

But parks, tree-lined streets, and backyard gardens would all be in jeopardy.

Oddly enough, Oregon's native white oak is unaffected, but red oaks would die, chestnuts and maples would grow weak, rhododendrons and azaleas would wither.

In some cases, the disease could be treated, but the cost would be enormous.

The best solution is prevention.

(fire crackling) - Some of our comfort in Oregon comes from the fact that we're doing all this cutting and burning, we're keeping the amount of disease pressure low, so it never seems too bad, it's never gotten out of hand.

But as soon as I go to California on a field trip and observe what's happening on some of their forests down there, I come back with a very different feeling because there they've seen flashes of 90 to a hundred thousand trees killed.

And once it gets rolling, it really behaves quite differently than it's doing in our Oregon forest.

- [Narrator] Even in Oregon though, the pathogen has proved difficult to outsmart.

This stream, for example, runs through an area that has undergone the full cut-and-burn treatment, yet leaves tested from these waters still carry the pathogen.

- The interesting challenge is that here you've got an organism that you know nothing about, and you're at the same time trying to eradicate it and study it to learn about it, so, because you can't do research out here, it's a quarantine pest, so you can't put plots out to see how it spreads, you can't test to see what treatments work.

So it's been challenging in that respect.

- [Narrator] One approach could be to let nature and this disease run its course.

Maybe things would work out.

But with each tanoak, each huckleberry bush killed, critical food sources are lost.

Bears, squirrels, and other forest species would no doubt suffer.

- We don't understand the long-term ecological impacts of losing tanoak from our stands, but I think you have to be careful about losing one of the pieces of the puzzle because we don't always know what the ramifications will be down the line.

And so it's just probably not a good idea to get rid of it all at once.

(laughs) - [Forester] We've got a single dead down here to our left- - [Narrator] Crews have fought hard to keep sudden oak death contained to the forest near Brookings and to a handful of nurseries.

But several years into the campaign, frustration is building.

- Well, one of the inspectors that I talked to the other day was, they supposedly hadn't found it in the eastern and southern places.

Well, they haven't looked for it.

(chuckles) So if you don't look for it, you can't find it!

I don't think that it is going to be worth what they're putting into it, and I don't think they're going to stop it.

- All of our field samples, all of the cultures, once we're done with them, gets autoclaved to be sure that it's dead.

- [Narrator] Five years after he saw the first Phytophthora ramorum specimen, Everett still sees infected plants arriving at his lab.

The end of sudden oak death, it seems, is not yet near.

- We've stuck our necks out a ways on this eradication effort.

There's no proof that this is going to work.

We went out and did the best thing we knew how to do, and I see the sacrifice that those landowners are making.

And I, you know, well, doggone, I hope in the end I don't have to say, "Sorry, (chuckles) it didn't really make any difference."

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