Sudden Oak Death Fungus: Looming Environmental (and Landscaping) Disaster?

Great Debates
1

Sudden Oak Death fungus, as you may know, has been ravaging California’s oak trees since 1995. I see from recent articles that the fungus is now beginning to appear in nurseries on the east coast: Georgia, Maryland, and Florida

I see that it has also made its appearance now in Great Britain

What little I know about this disease sounds pretty scary: high mortality rate for oaks, plus the fungus is able to infect numerous non-oak hardwood species (though not with the same degree of fatality that oaks experience, apparently).

Are we on the cusp of an ecological disaster of gigantic proportions? Old timers may remember the way Dutch Elm disease ravaged elm tree populations, and blight destroyed American chestnut trees.

But oaks? That’s scary.

Oaks make up a very large percentage of trees in eastern forests. And I can’t speak for other cities, but the great majority of Atlanta’s shade trees are oaks. I’d guesstimate something like 75%. If these oaks were killed, Atlanta would look awfully naked. The “City in a Forest,” as Atlanta sometimes likes to bill itself, would look more like a “City on a Parking Lot.” I suspect the same is true for many cities in the east and midwest.

So is this fungus cause for alarm? Can it be stopped? Are eastern US species threatened?

I suppose this post is part GD and part GQ. I’m inviting exposition with those with information about this disease, and debate on its long-term effects.

Any thoughts?

2

Mostly that if the Atlanta oaks were killed, Atlanta would eventually, after a period of public mourning by politicians and hand-wringing Sunday supplement articles by environmental activists, collectively shrug and plant other trees. Probably those “poplar” trees from the back of the Parade magazine, “grows 50 feet in a single year!”

We’ve heard too many “Oh no! X is going extinct!” crises to get all worked up about this one, I think. Elm trees disappeared–Norway maples were “discovered” and planted equally widely (God help us). And the American chestnut really only exists in history books, so nobody that I know gets really cranked up about chestnut blight.

Now, ya wanna hear people get upset about tree ailments–talk about tent caterpillars.

3

And, my guess would be that no, it can’t be stopped. They haven’t had much luck stopping it in California. Stuff like this moves in and basically Nature just takes over. It’s a fungus. We can’t even keep fungus off our feet and shower curtains, and we have way more control over those than over millions of square miles of Nature.

4

No indeed. I know of a number of places on the east coast where the chestnut survived. In any case, it wouldn’t be the same at all, because oaks make up a huge percentage of some of our most ecologically important and widespread forest land. Hell, I think “basic mesic forest” is pretty much by definition an oak-canopied forest on a mid-slope. Oaks occur in every possible environment type in Eastern forests. Bottomlands? Water oak, white oak, even red oak. Check. Mid-slope? Turkey oak, red oak, white oak, scarlet oak, pin oak. Check. Xeric ridgelines? Black oak, scarlet oak. Check. Coastlines? Live oak, scrubby red oaks. Check.

They are mature forest canopy, and they are essential to the ecology of the Eastern forest.

If we lose the oaks, it will be an ecological domino effect of far greater scale than the loss of the chestnut (or the elm,) both of which were bad enough. There are birds which preferentially nest in oaks. There are plants that are parasitic on oak roots, and can not live on any other. There are whole environmental niches that will go tits-up if the oaks go (blackwater rivers and swamps, etc.)

This would be very, very bad.

5

So is this yet another case of humanity screwing itself? I ask because the link in the OP describes this as “newly discovered” (even if it’s not a result of our pollution or whatever, its spread and virulence could still be our responsibility, considering how much cross-contamination humanity does every day), and it sounds like, at least in the OP’s and Ogre’s POV, that if so, we humans have just destroyed a huge part of the natural world.

Again.

6

Just to clarify, I didn’t say anything about blaming humans in the OP. We didn’t create the fungus (though we may be spreading it inadvertently).

I started the thread to discuss ways of controlling the fungus (if any), and the potential environmental impact if we are unable to do so (huge, IMO).

7

You may know of a number of places where Asian chestnuts grow, but as far as I know there aren’t any places left where there are American chestnuts unaffected by blight.

There was a good article about chestnuts in last month’s issue of Discover magazine. It said that, a century ago, chestnuts made up “more than a quarter of eastern woodlands.”

8

And surely some tree would, a century hence, fill the spaces left by fallen oaks. But we’d have a mess on our hands in the meantime. Not to mention a lot of starving squirrels.

What might take the place of oaks, I wonder? First guess might hickory, since that’s an alternate food source for squirrels (who will help plant the things in the absence of acorns). I don’t know if hickories are succeptable to the disease, though. The fungus seems pretty adaptable to different species, and I’m not sure which species might prove most resistant, and thus most likely to replace oaks, should they perish. Maple? “Tulip poplar” (so-called in these parts)? What?

9

I said “survived.” This is a different term from “unaffected.” Castanea dentata survives in a number of places because of a remarkable survival adaptation it has. When the tree is under stress, it sends up shoots from its large root system, which is not killed by the chestnut blight. In some few cases, the new chestnut shoots flower and seed before the blight kills them. Therefore, yes, the American chestnut is endangered, but not dead. Just in grave, grave trouble.

So why would oaks be worse? The loss of American chestnut constitued a devastating loss, and that was just one species. This new fungus threatens all surviving oak species, as far as I can tell, PLUS is readily adaptable to others. Can you imagine losing pin, blackjack, laurel, northern red, southern red, live, white, black, scarlet, chinquapin, chestnut, pagoda, post, overcup, oglethorpe, chapman, georgia, turkey, water, bear, shingle, myrtle, willow, and all the various swamp oaks? We’re talking about the loss of an entire genus here, with the added potential of losing other dominant forage hardwoods as well. So if we lost a good percentage of, say, our oaks from the fungus, then suffered a loss of a smaller percentage of other hardwoods, say, hickories and black walnuts, I’d say it’d be a death-blow to the Eastern hardwood forest as we know it.

The diversity in terms of trees, and obligate herbs and shrubs, would fall through the floor. A number of already teetering endangered species would die, and I;m not sure we could expect to see any recovery for some of the more exotic oak-dominant ecologies, such as the oak tannin-dependent blackwater habitats, the scrub-oak coastal habitats, etc. The basic mesic forest might (MIGHT) recover eventually, but not before a lot of the shade-dependent sensitive plants got a lot scarcer. Virtually every understory plant we are familiar with would take a hit. Trilliums, ginseng, hexastylis, goatsbeards, the various and sundry forest mints, skullcaps, any number of cryptic Asteraceous species, Apiaceous herbs like angelicas, etc.

I predict it would be like Yellowstone losing most of its lodgepole pines in the great fires of the 80’s. An ecological trainwreck.

10

And yet, Yellowstone still exists. The ecology is changed, but plants and animals are thriving.

If one quarter of the eastern forests were destroyed circa 1900, then then oaks that replaced them did a very good job. I’m seeing a problem here, because I like oaks forests, but unless it can be shown that the fungus has a human cause, or has a primary human vector, I really don’t see what there is to debate. Looming disaster…maybe. But the world will adapt.

11

Of course it will adapt, but the question is what will it look like when it’s all over? The Eastern hardwood forest, especially the Southeastern hardwood forests, are much more diverse than those of Yellowstone, and an exotic blight would be far more devastaing than a fire. I drew an analogy, but the loss of the oaks would be much worse for the Eastern ecosystems. A much larger number of species and specialized habitats would be put in grave danger, not to mention leaving the dominant trees left that much closer to a monoculture, which would leave the forest that much more vulnerable to the next thing down the pike.

The best we could hope for in that situation is that it is indeed a natural event. Natural events (like, frex, the pine bark beetle outbreak) have a lifespan. They burn themselves out without fundamentally altering the makeup of the ecosystem (well, too much.) An exotic infestation (and to my mind, that it apparently “jumped” from California to the East indicates that human vectoring had at least something to do with its spread) has no such controls. Witness, the aforementioned American chestnut blight, which was demonstrably anthropogenic.

12

This makes me sad. I can only hope a cure is found before the same sort of devastation that nearly wiped out the chestnut trees takes its toll on the oaks.

I once saw a picture of a sub-urban street before and after the chestnut blight. Before was a manificant green gothic church like vista with streamers of golden-green sunlight filtering down. After was typical ugly American suburban sprawl with a few small trees here and there. I only hope the forests don’t become nearly as barren,oaks are beautiful trees.

13

I’m trying to think through some of the other potential consequences, if the oaks die. There are a lot of them.

For example, deer (and other wildlife) depend heavily on acorns as a food source in the fall. Herds of starving deer will be roving the countryside.

Our eastern national forests and state forests are mostly oak, if I am not mistaken. If more than half the trees in a forest are dead and dry, you have a potential forest fire problem of frightening proportions.

Fewer trees means fewer leaves to convert CO2 into oxygen. (At least until a replacement species moves in.) That means increasing CO2 levels throughout the US, and anywhere oaks dominate.

Cities are “heat islands” as it is. Without the big oak trees that shade many cities, that problem will be greatly exacerbated. And with increased heat in urban areas, you get increased ground-level ozone problems, and stifling smog.

I can’t believe this story isn’t getting more media play.

14

Ogre: *An exotic infestation (and to my mind, that it apparently “jumped” from California to the East indicates that human vectoring had at least something to do with its spread) has no such controls. *

The links in the OP seem to bear out your guess, e.g.:

If imported ornamentals from California were indeed the carrier (and we can only hope that none of the fungus has got outside the nurseries, though that seems rather optimistic), it’s a sort of eerie reversal of the disastrous infestation of California vineyards by the glassy-winged sharpshooter accidentally imported in ornamentals from the southeastern US; a sort of pestilential free trade, as it were.

If there’s one general, easy lesson to be learned here, I think it’s this: PLANTS NATIVE TO YOUR REGION ARE PREFERABLE FOR LANDSCAPING. A lot of people drooled over garden varieties of purple loosestrife and Japanese knotweed and so forth, and look what happened with them. Play it safe and plant the plants that naturally grow in the areas where you live, and think twice before deciding that you absolutely must have some gorgeous ornamental from across the country or around the world. Local plants not only are generally better adapted and require less care and resources, but they reduce the risk of spreading environmentally and economically crippling pests and monocultures.

(looking around, stepping off soapbox) ahem Yes, well, 'night.

15

Your fingers to everyone’s ears, Kimstu.

Let me also add that if you’re interested in bird or butterfly gardening it’s best to use native plants as those have the highest likelihood of attracting both native and migratory birds as they’ll be looking for those plants on their travels.

16

Precisely, Kimstu. I’ve always had trouble seeing why, in the case of the southeastern United States (where I’m from,) people simply must landscape with exotic species. Japanese magnolia, princess tree (that plague upon the earth,) loosestrife, tree-of-heaven (that other plague upon the earth,) etc. Hell, you’d think we’d have learned after what happened with kudzu.

The only thing I can figure is that people are desperately interested in having something new and unusual. Ironically, most of our gorgeous native plants have fallen by the wayside, and really would be spectacularly unusual in landscaping. American smoketree, for instance. Or butterfly weed. Or pitcher plants.

Bah. There are thousands of plants to choose from.

17

Ogre: Ironically, most of our gorgeous [southeastern] native plants have fallen by the wayside, and really would be spectacularly unusual in landscaping.

Yeah! I was always intrigued by the recurring rumors of discovery of a surviving wild specimen of Franklinia altamaha—a flowering tree discovered by American botanists in Georgia in the 18th century but now apparently extinct in the wild—which seems to be a sort of perennial rural urban legend. I always thought it would be extremely cool to grow a Franklinia, but I don’t expect to reside in zone 7 and I hear they’re hard to grow anyway. Still, that sort of living history, both natural and social, to my mind has a lot more pizzazz than some mass-produced hybrid exotics from a nursery, besides being better for the environment in general.

18

Ogre: Or pitcher plants.

You gotta love a plant that’s featured in a book called Gardening with Carnivores. Now that’s exotic. :slight_smile:

19

The media are beginning to catch on.

20

I have a pin oak, very tall, and a sapling scarlet oak. I would be very sorry to lose either. Scarlet oak is especially interesting; if you turn over a leaf of one and look at it, you’ll see “hair” growing where the leaf veins part. Has hair in its underarms, as it were. Neat.
Also, speaking as someone who is deliberately trying to make sure to grow jewelweed, pink beauties, butterfly weed, viburnum, tulip trees, the aforementioned scarlet oak, and American bittersweet, all of which I have found growing within walking distance of my house, (in the case of jewelweed, the scarlet oak, and pink beauties I found them in my backyard. Jewelweed is a highly interesting orange color, and attracts hummingbirds. Pink beauties I have seen used massed, which is the proper way to do it, as they are small and inconspicuous otherwise. Can’t get them from a nursery, though.) I can only second Kimstu. Walk around where you live, note what grows, and look it up: if you like it and it’s not alien, grow it. The birds and the butterflies will love you for it, and you’ll have a garden which is both beautiful and enchanting to just sit and watch as the birds and butterflies move through it.
Of course I also grow stuff that isn’t native to where I live; I’m not a purist. But I make a special effort to grow natives, partially because their habitat is what has been torn up to make room for the housing. Natives are also, by and large, ridiculously easy to grow, because, after all, they’re native.
Recommended reference books to have around for looking up native stuff: Peterson’s Wildflowers in his Field Guide series, and the American Audobon Society’s Field Guide to Trees for your area, broken up into the Eastern and Western US.