Christian Science Monitor

A mention in Christian Science Monitor's informative article: 

 By Moises Velasquez-Manoff, Staff writer of The Christian Science Monitor
 August 2, 2007

Hemlocks threatened by an unwelcome guest

Scientists are working to stop the hemlock woolly adelgid from killing trees in the Eastern US and spreading northward.

Boston's Arnold Arboretum is a place to marvel at the deep, dark shadow cast by the eastern hemlock tree, sometimes called the "redwood of the east." It's also a place to observe the devastation wrought by a tiny bug: the hemlock woolly adelgid.

Originally from East Asia, the pest attaches to the base of the conifer's needles. There, it spins a small woolly sac that, in shape, size, and texture, resemble lint balls found in pockets of old blue jeans. Stressed beyond what they can withstand, the trees gradually lose their needles, go gray, and die over a period of four to 10 years.

Scientists first detected the pest on the arboretum's Hemlock Hill in 1997. They had long foreseen – and dreaded – its arrival. "It was not if, but when," says Richard Schulhof, deputy director of the Arnold Arboretum.

And yet, some hope that the infestation won't be as catastrophic as in the Southeastern United States, where many fear the adelgid could eat the Carolina hemlock out of existence. Massachusetts lies at the northernmost extent of the adelgid's potential range in the Eastern US. Adapted to the maritime climate of its native Japan, the insect can't survive New England's cold winters. Indeed, during the winters of 2004 and 2005, extreme cold snaps beat the adelgid back. In some places, 90 percent died. A wet summer helped also, improving the trees' resistance. "We had a favorable one-two punch," says Mr. Schulhof.

But then came the warmer-than-average winters of 2006 and 2007. "If we don't have some cold winter minimums, the adelgid will expand," says Schulhof.

And this is what worries scientists most. The world is warming and the vast majority of scientists fault human-emitted greenhouse gases for the rising temperatures. In a warmer world, they predict that pests formerly limited by the cold will move farther north. The Northeast has warmed about 1.5 degrees F. in the past 30 years. But the warming hasn't occurred evenly.

"The warming is a lot greater in the winter," some 4 degrees F., says Scott Ollinger, a professor of natural resources at the University of New Hampshire in Durham. And for the adelgid, cold snaps are the limiting factor. "It would be hard to imagine that some of the northern movement wouldn't be attributed to the warming," he says.

Scientists call hemlock a "keystone" species, meaning that it has an outsized role in defining ecosystems where it's found. Many worry that its disappearance could alter forests in unforeseen – and unpleasant – ways.

Fighting back with soap, oil

Seeking to avoid unwelcome changes to Eastern forest ecosystems, a phalanx of scientists has been working on ways to control the infestation. Pesticides, soaps, and oils work wonders on individual trees, but they're difficult and expensive to apply to entire forests. This has scientists seeking a "biocontrol" – a predator or disease that, once released, will continuously restrict the adelgid population.

In the meantime, working with partners, the US Forest Service is establishing hemlock nurseries in South America and Arkansas's adelgid-free Ozark Mountains to ensure that if and when a solution is found, restoration is possible.

In the Eastern US, hemlocks come in two varieties, the Eastern hemlock in the north and the Carolina hemlock in the south. In southern Appalachia, where hemlocks tend to cluster around water, their shade helps keep streams cool.

"We're at the tipping point for where temperatures can support trout populations," says ecologist James Vose, project leader at the Coweeta Hydrologic Laboratory in Otto, N.C. "Hemlock is really important for providing the shade. It keeps the environment cool enough for trout to survive."

During the summer, air temperatures beneath hemlock trees are 5 degrees C. lower than in the open air, the equivalent of being 300 miles to the north, says Julian Hadley, a plant eco-physiologist at Harvard Forest in Petersham, Mass. "It has a strong effect on the microclimate," he says.

In the Northeast, where the hemlock grows more evenly throughout the forest, they provide an important overwintering site for deer. They also slow the spring runoff by shielding snow from the sun. In both North and South, fallen hemlock needles create a mat of organic matter on the forest floor. Slow to decompose because of high tannin content, the mat provides habitat and nutrients for many other species.

But maybe the greatest worry is the hardest to quantify. During the first half of the 20th century, a blight eliminated the American chestnut from Eastern forests, another keystone species. How much more can a forest ecosystem take before it collapses and shifts radically?

"As ecologists, we worry about 'What is the tipping point?' " says Dr. Vose. "It seems that when you lose these keystone species, you have the possibility of reaching that tipping point sooner."

In Tennessee's Great Smoky Mountains National Park hemlocks tower 150 feet and can reach 500 years old. There, scientists are protecting hemlock stands with insecticidal soap or horticultural oil sprayed from trucks. (The Arnold Arboretum also sprays trees near roads with the oil, which suffocates the bugs.) Where the hemlock grows near campsites and spraying is impossible, scientists directly apply imidacloprid, a pesticide, by injection or by soaking the soil around the tree's base.

But none of these treatments can be applied on a large scale. This fact has scientists looking for the perfect natural predator, one that can breed in its new environment and survive the Northeastern winters, but not become a pest in its own right. After testing many beetles with mixed results, scientists think they have a good candidate. Laricobius nigrinus, a beetle native to the Pacific Northwest, can survive New England's cold snaps, and can only complete its life cycle on the hemlock woolly adelgid.

"I'm quite hopeful that this enemy and over­winter mortality could actually save the hemlocks in Massachusetts," says Joe Elkinton, a professor of entomology at the University of Massachusetts, Amherst, who has wrapped trees, adelgid, and beetle together in netting with promising results. "I'm confident we can stem the tide."

Scientists also are studying an even better candidate: a Japanese relative of the laricobius. "We're pretty happy about it because this is an insect that's adapted to [the eastern US] strain of hemlock woolly adelgid," says Scott Salom, a professor of forest entomology at Virginia Tech in Blacksburg, Va.

Approaching the problem with fungus

For years, Scott Costa, a research assistant professor at the University of Vermont in Burlington, and his graduate student, Stacie Grassano, have been developing a slightly different approach. He aims to jump-start a disease that would kill the adelgid. He mixes a naturally occurring fungus with sweet whey, a protein- and sugar-rich byproduct from cheesemaking, and sprays it onto infested trees. Prompted by the food source, the fungus emits hundreds of spores, eventually killing the bugs.

"You want to get enough spores out there so that a disease outbreak does occur," he says.

If effective, this approach has the advantage of not introducing potential pests into the equation, and of being considerably cheaper compared with other methods.

"If we get nature to work for us, there's a potential for economic windfall," he says.

The adelgid's historic trail

The saga of the hemlock woolly adelgid begins in Eastern North America almost 90 years ago. Scientists think that, perhaps as early as the 1920s, an ornamental tree infested with the bug arrived at a private plant collection in Richmond, Va. That plant enthusiast's estate, which still housed the tree, eventually became Maymont Park, where scientists first detected the adelgid in the early 1950s.

From there, maybe by hitching a ride on migratory birds or through inadvertent human transport, the adelgid jumped to wild hemlocks.

By the late 1960s, it was established in Pennsylvania. After Hurricane Gloria in 1985, it appeared in Connecticut, causing many to suspect that winds play a role in its dispersal. In 1991, it showed up in Springfield, Mass. (It only arrived in parts of Southern Appalachia in the early 2000s.) Earlier this year, the adelgid was found in Vermont.

"At my house, I always thought I was safe; I live in northern Vermont," says Scott Costa, a research assistant professor at the University of Vermont in Burlington. "I don't feel particularly safe anymore." (Nov. 2006)

– Moises Velasquez-Manoff

Vermont Quarterly

The UVM Connection, Vermont Quarterly, Spring 2007 Alumni Publication 

this article mentions the developers who isolated the fungi for use

Fungal fighter

The eastern hemlock is in trouble. From Georgia to Maine, this once-mighty conifer is now succumbing to an exotic pest, hemlock woolly adelgid. First detected in the western United States in 1924, the adelgid caused little damage. But when it was carried east and reached Virginia in the 1950s it began its destructive spread. An aphid-like insect, the adelgid kills eastern hemlocks within a few years after infestation, feeding on the sap at the base of their needles and cutting off their nutrients.

It’s a pressing problem: In Shenandoah National Park most of the famous towering hemlocks are now dead. The adelgid has ravaged parts of Kentucky, North Carolina, and the Smoky Mountains. Expanding northward, it has moved through Massachusetts into southern Maine and New Hampshire.

The only natural deterrent to the adelgid seems to be a very cold winter. With global warming, their northward spread seems inevitable. Though not officially recorded yet, “it’s probably in southern Vermont now at population levels too low to easily detect,” says Scott Costa, research assistant professor of plant and soil science, who anticipates that the adelgid will be into the Champlain Valley in not too many years.

New research in UVM’s department of plant and soil science, though, could aid the hemlock’s survival. Last December, Costa, graduate student Stacie Grassano, and two other researchers, Vladimir Gouli and Jiancai Li, submitted a provisional patent for a new method of cheaply and effectively spreading a strain of  fungus called Lecanicillium muscarium, and other similar biological controls, that might beat back the adelgid without having to use expensive, toxic pesticides. They call their approach a “whey-based fungal micro-factory.”

Instead of growing fungi in a conventional factory and then transporting it out to a forest—a costly proposition—their factory will be the forest. Or, more accurately, tiny droplets of sweet whey—a cheap waste product of cheese production, inoculated with the right concentrations of the target fungus—will be their factory. By spraying the whey solution into an infected forest, they believe they can get the adelgid-killing fungi to reproduce in large numbers on its own.

Costa and Grassano’s experiments on branches taken from adelgid-infected forests in Massachusetts are proving highly successful, with rapid growth of the target fungi out-competing other fungi that live on hemlocks. If their laboratory tests continue to go well, the researchers anticipate starting field trials in 2008. 

The economy and ease of the UVM team’s whey micro-factory technology might prove a critical consideration for land managers—especially in large areas with low economic value, like wild hemlock forests.

“We’re not going to eradicate the adelgid,” Costa says. “The best-case scenario for insect-killing fungi is you inoculate the environment and get disease outbreaks to start cycling. The idea is to reduce the pest population to a level that is manageable, allowing some of the trees to make seeds, grow, and survive.”

The Boston Globe/The Washington Post

The Boston Globe and The Washington Post publishing the Associated Press release, February 2, 2007


UVM researcher targets hemlock pest with whey and fungus

By Lisa Rathke, Associated Press Writer  |  February 2, 2007

MONTPELIER, Vt. --A University of Vermont researcher is using the dairy product whey and a fungus to take aim at a pest that has ravaged East Coast hemlocks.

Scott Costa said the method will allow an insect-killing fungus to grow in the field rather than in a laboratory, cutting down on the prohibitive costs.

"The technology gets over some of the financial and physical restraints," said Costa, assistant professor in UVM's plant and soil science department.

The fungus and sweet whey, a cheese-making byproduct, is sprayed on trees to kill the hemlock woolly adelgid, an exotic pest that is wiping out native trees from Tennessee to Massachusetts. As the fungus reproduces in the whey, Costa and his graduate students have evidence that the spores will spread throughout the trees, piercing the skin of the insects.

The technology has worked in the lab and on trees in Massachusetts.

"Now we have work to transfer it out into natural settings," said Costa, who is seeking funding for small-scale spraying by helicopter.

Costa, who has received a provisional patent, hopes to have the technology operating in two years.

"We're not going to get rid of the hemlock woolly adelgid, we're going to manage it," he said.

Still that's good news.

"HWA is a pretty noxious insect. Certainly, any kind of controls that we can come up with that are ecologically safe and effective is well worth it," said Talbot Trotter, a research ecologist with U.S. Department of Agriculture Forest Service in Hamden, Conn.

Infested trees have been found in New Hampshire, Maine and Massachusetts, not far from Vermont. 

Although no adelgids have been found on native trees in Vermont, Costa thinks the insect has crossed the state line.

The state has banned the importation of hemlocks -- nursery stock, boughs, hemlock bark mulch -- from infested areas of the U.S. and Canada. Shipments of hemlock must be inspected for pests, before and after shipping.

One advantage the state has is that cold winters kill the adelgid, which take about five years to kill trees in the north and two to three years in the south, Costa said.

To fight the bug, beetles have been released, and trees sprayed with oils and injected with chemical pesticides.

Costa thinks his "whey-based fungal micro-factory" technology has broader applications than adelgid control.
 
If it can down reduce the use of chemical pesticides - "even by a small amount it would be amazing," he said.

----------
On the Net:
Hemlock Woolly Adelgid: http://www.na.fs.fed.us/fhp/hwa/

Science Daily

When Science Daily published its press release from UVM, the HWA/MycoMax story quickly went to major science sites in just about every major country. (The Science Daily is actually published before the UVM story, even though UVM released it.)

Holding an eastern hemlock branch, University of Vermont researcher Scott Costa points out the the white growth of hemlock woolly adelgid. Costa's new "whey-based fungal micro-factory" technology promises to control this exotic pest. (Image courtesy of University of Vermont)

It Starts Here: UVM's "The View"

Joshua Brown's article in University of Vermont's web news source, The View:

Fungal Fighter

By Joshua Brown   Article published January 30, 2007

Researcher Scott Costa has invented a "whey-based fungal micro-factory" technology that may save the eastern hemlock tree species from an exotic pest. 

Reaching into a box glowing with fluorescent light, Stacie Grassano pulls out a tube. “This is a great one,” she says, holding the clear plastic up to her face. Inside, a tree branch is speckled with white fluff. “It’s growing really well,” she says, handing it to Scott Costa.

Costa brings the branch close to his eye. “Yes,” he says, with a boyish grin, “this is a fungus success story.”

For some, a fungus success story means nothing is growing at the back of their refrigerator. But for Costa, research assistant professor of plant and soil science, and Grassano, his graduate student, the vigorous growth in their laboratory of this fungus, a strain called Lecanicillium muscarium, means a hopeful new chapter in the otherwise bleak tale of the eastern hemlock tree.

Battling an exotic pest
From Georgia to Maine, this once-mighty conifer is now succumbing to an exotic pest, hemlock woolly adelgid. First detected in the western United States in 1924, the adelgid caused little damage. But when it was carried east and reached Virginia in the 1950s it began its destructive spread. An aphid-like insect, the adelgid kills eastern hemlocks within a few years after infestation, feeding on the sap at the base of their needles and cutting off their nutrients.

While the adelgid, originally from Japan and China, appears to have no successful predators in North America, some native fungi — like the one Costa and Grassano have growing on branches in their laboratory — kill the pest.

Last December, Costa, Grassano, and two other researchers, Vladimir Gouli and Jiancai Li, submitted a provisional patent for a new method of cheaply and effectively spreading the fungus, and other similar “biological controls,” that might beat back the adelgid without having to use expensive, toxic pesticides. They call their approach a “whey-based fungal micro-factory.”

Instead of growing fungi in a conventional factory and then transporting it out to a forest — a costly proposition — their factory will be the forest. Or, more accurately, tiny droplets of sweet whey — a cheap waste product of cheese production, inoculated with the right concentrations of the target fungus — will be their factory. By spraying the whey solution into an infected forest, they believe they can get the adelgid-killing fungi to reproduce in large numbers on its own.

“The sweet whey only costs 32 cents a pound,” says Costa, who gets his donated from a New York-based cheese company and receives support for his research from the US Department of Agriculture.

The whey is a far cheaper growing medium than those typically available in labs, and it serves as a nutritional resource, making each droplet a cozy biological factory for a fungal colony, pumping spores out into the forest long after the spraying teams have gone home.

Costa and Grassano’s experiments on branches taken from adelgid-infected forests in Massachusetts are proving highly successful, with rapid growth of the target fungi outcompeting other fungi that live on hemlocks. If their laboratory tests continue to go well, the researchers anticipate starting field trials in 2008. And beyond the adelgid, the researchers anticipate that micro-factories could be used with fungi that attack other insects, weeds and even plant diseases.

The economy and ease of the UVM team’s whey micro-factory technology may prove a critical consideration for land managers — especially in large areas with low economic value, like wild hemlock forests.

“We’re not going to eradicate the adelgid,” Costa says. “The best-case scenario for an insect-killing fungi is you inoculate the environment and get disease outbreaks to start cycling. The idea is to reduce the pest population to a level that is manageable, allowing some of the trees to make seeds, grow and survive.”

Time becoming crucial factor
It’s a pressing problem: In Shenandoah National Park most of the famous towering hemlocks are now dead. The adelgid has ravaged parts of Kentucky, North Carolina and the Smoky Mountains. Expanding northward, it has moved through Massachusetts into southern Maine and New Hampshire.

The only natural deterrent to the adelgid seems to be a very cold winter. With global warming, their northward spread seems inevitable. Though not officially recorded yet, “it’s probably in southern Vermont now at population levels too low to easily detect,” say Costa, who anticipates that the adelgid will be into the Champlain Valley in not too many years, though whether it would soon reach the coldest parts of the Northeast Kingdom seems unlikely. 

While the era of cutting hemlock for the tanning industry is over, there continues to be use of the tree for fiber and construction, and commercial forest owners have something to lose with the demise of the hemlock. But far more important, as the hemlocks expire they take an ecosystem down when they fall. 

In cool hollows and along shady mountain streams the hemlock has grown for millennia where other trees wouldn’t thrive: a quiet giant soaring to over 150 feet. With a range from Alabama along the Appalachians into the Canadian Maritimes, its shaggy crown creates a blueish green haven unmistakable to turkeys and deer (and hunters): a thick understory of duff with a unique plant community, deep with shade that accentuates the black furrows of the hemlock’s tannin-rich bark. 

In winter, chickadees eat the small seed cones of the hemlock and they are only one species of many that depend on the hemlock not just for food but for the architecture of their world. Some warblers only nest in hemlocks and mountain-spawning fish depend on the trees to keep streams cool. 

“See all this white growth?” Costa says in his lab in Hills Building, tracing his finger above the soft flat needles. “That’s mycelium and likely as not there are spores at the end of each of those.” To the untrained eye, the fungus he and Grassano are growing looks much like the pest they hope it will fight. Hiding on the underside of hemlock branches, the pest produces a white woolly tuft that gives it its name. The fungus looks white and woolly too. But the subtle difference may mean life or death for the eastern hemlock.