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Thursday
Nov212013

Emerald ash borer: a voracious pest nears Maine

By Joe Rankin

Forests for Maine's Future writer 

When the emerald ash borer arrives in Maine everyone will lose, but the state’s native American tribes have more to lose than most.

The ash is a valuable hardwood: straight, tall, with a beautiful open grain; producer of prime firewood. The three ash species that grow in Maine are key components of their ecosystems. But for the Penobscot, Maliseet, Micmac, and Passamaquoddy, the black ash, also known as the brown ash, is not just a tree -- it’s part of who they are as a people.

Adult emerald ash borer (Photo: USFS)In one creation legend, they exist because of the ash. It is said that Glooskap, the culture hero of the Wabanaki, took his bow and fired arrows into the “basket trees” -- black ashes -- and the people emerged from the bark into the world.

From time immemorial, since long before white settlers drifted over the eastern horizon like gulls on the wind, the tribes used the wood of the black ash to make elegant and useful baskets. It was an art form, continually renewed, passed down the generations. In the latter decades of the twentieth century, it was in danger of dying out. Those with the skills were growing old, and young people were not taking up the art.

In 1993 the Maine Indian Basketmakers Alliance was formed to reverse that trend, and has nurtured young basketmakers, like Jeremy Frey of Princeton, a Passamaquoddy basketmaker who has won top honors at national shows, including the Santa Fe Indian Market, for his breathtakingly beautiful, intricate split ash baskets that sell for hundreds and thousands of dollars.

Now, a tiny beetle from Asia threatens to undo that entire effort. Indeed, it threatens the very existence of the continent’s ash trees. Not just one species -- every species of Fraxinus, the genus of ash.

“We’re alarmed,” said Theresa Secord, a Penobscot, a basketmaker and the executive director of the MIBA. “The sacred ash is woven into our identity as a tribal people in Maine, as well as our baskets. After 20 years of work to save ash basketry by increasing basket prices, teaching an entire new generation of weavers and intensive marketing efforts, the EAB will be the one thing we can't do anything about.”

The emerald ash borer, Agrilus planipennis, is about half an inch long and a sixteenth of an inch wide. It is a sporty, iridescent metallic green, a color that would look good on a Maserati. It has black eyes. In its native habitat -- northeastern Russia, China, Korea -- the beetle is considered only an incidental pest.

Point basket by Ganessa Bryant (Photo: MIBA)Sometime in the early 1990s, it found its way to North America, probably in wood packing material. In Asia, it had virtually escaped notice and alarmed no one. Transplanted half a world away, with a smorgasbord of four ash species and eight billion stems spread before it, and no natural predators, the beetle went into a feeding frenzy.

It was initially found near Detroit, Mich. in 2002. 

By this year the borer had spread to some two dozen states and provinces from Colorado to Quebec to Georgia. Its spread was enabled by people transporting infested firewood or logs and interstate sales of nursery stock, as well as its own ability to fly. State governments imposed quarantines on wood movement in a well-intentioned, but largely futile, effort to slow its spread. Hundreds of millions of trees across the entire spectrum of North American ash -- white, green, black and blue -- have been killed. The rest are at risk. The borer has been compared, without hyperbole, to the blight that wiped out the American chestnut in the early years of the twentieth century and the fungus that did in the grand old American elm a few decades later.

It’s in the larval stage that the beetle does its fatal damage. 

The adult female lays eggs on the bark. The cream-colored, inch-long larvae that hatch out bore into the tree and tunnel through the inner bark, creating S-shaped galleries. The galleries effectively girdle the tree, depriving it of nutrients and starving it to death. The larvae pupate beneath the bark and the adult chews its Passamaquoddy Tribe basketmakers Jeremy Frey (kneeling) and Matt Dana looking at EAB damage in Michigan during a 2010 fact-finding trip. (Photo: MIBA)way out, exiting through a distinctive D-shaped hole. The beetle’s life cycle takes a year, two years sometimes in colder climates. The adults emerge in the warmer months, June is high emergence season, and are capable of immediate flight. Now with only a few weeks to live, they feast on ash leaves in preparation for mating. The female lays up to 100 rust-colored eggs.

Last March, samples taken from an ash tree in Concord, N.H. were confirmed to be emerald ash borer. The bug has since been found in trees up and down the Merrimack River Valley. The insect had already been found in New York and western Massachusetts. But with the Concord discovery the front lines leapfrogged a lot of real estate. Maine scientists say it is inevitable that the emerald ash borer will find its way to Maine’s forests, where ashes make up some 7 percent of the trees. 

When, exactly? Well, sooner rather than later. 

Dave Struble, the Maine state entomologist, puts it at five years. Max. 

“I’m very concerned. People should be concerned,” Struble said. “You don’t have to go into a blind spiral panic. But this beetle has been spreading. It’s in Quebec so it’s not far away from us to the north. The fact that we have an infestation 35 miles from Maine’s border points to the inevitability of it getting here through natural spread. And it remains a possibility that we have an infestation in Maine already that is so low level it hasn’t come to anybody’s attention.”

Maine researchers have been monitoring for the borer for the past few years. In 2013 a coalition of four agencies -- the Maine Forest Service, the Maine Department of Agriculture Conservation and Forestry's Division of Animal and Plant Health, the federal Animal and Plant Health Inspection Service, and the Penobscot Nation -- deployed 853 purple box traps -- the beetle seems attracted to purple -- around the state, part of a national monitoring effort. All turned up empty. That’s good news. Sort of. Struble said the traps aren’t very effective. There’s no good pheromone attractant for the borer, he said. “I don’t know that we will ever have a pheromone that is wildly attractive. The beetle doesn’t have a highly evolved olfactory sense. If you look at it you see it has big eyes. An awful lot of its effort at finding food may be done with eyes,” he said.

Ash leaves. (Photo: MIBA)For the past two years the MFS has also created “trap trees” by girdling them. The borer seems attracted to trees under stress, perhaps sensing they are more vulnerable. And girdling certainly does that. Trees girdled in 2012 were cut and the bark peeled this past spring, but no borers were found. Struble said the trap tree program was expanded in 2013 to include trees in private, public and state-owned campgrounds as well as a street tree in South Portland and an ash on private land where symptoms of EAB had been seen. Those trees won’t be felled and examined until next year.

In addition, MFS researchers have a biosurveillance program ongoing. They are monitoring colonies of a ground-nesting wasp -- Cerceris fumipennis -- that is known to hunt buprestid beetles -- the globe-encircling family of iridescent wood-boring beetles of which emerald ash borer is one. “It’s kind of like hunting rabbits in thick brush. You can’t see the rabbit, so you watch the dog,” said Struble. “In this case we’re watching the wasps to find the beetle.” But so far, no EAB.

The MFS has also worked to educate the public about EAB. And it could be that the first beetles in Maine get spotted by an alert citizen who has read a flyer, surfed the MFS's website, or glanced at a bookmark and reports the sighting using a cell phone, emailing a photo at the same time.

“It’s a lot like cancer. You don’t want it. But if you do have it you want to find it early,” said Struble. Because then you have a chance to curb its spread.

Maine has had a firewood quarantine in place for a couple of years, with the Maine Forest Service even offering firewood exchanges to tourists at interstate rest areas. Of course, it only takes one armload of infested wood to negate the whole effort.

With the arrival of EAB imminent, Struble is constantly asked by landowners what they should do about the stands of ash on their property. “I tell people, if you’re planning a harvest right now and you have any ash of This older ash's heavily fissured bark would be preferred for egg-laying by EAB females. (Photo: The Rankin File)value you ought to take it now. Because you’re not going to be back in that area again in 15 years. Put off harvesting the maple or birch and take the ash.”

From the emerald ash borer’s perspective, all true ash species are food. But, like everything, it has preferences. Green and black ash are on the top of its fine foods list, with white ash following. Blue ash, which grows in the midwestern U.S. and parts of western Tennessee and Alabama, seems to show some resistance to the borer, though it usually succumbs as well.

Ash has long been a valued hardwood, used for everything from furniture to tool handles to snowshoes to moldings. Black ash, AKA brown ash, the “basket tree” of the Maine tribes, is not common in the state, growing in scattered sites, often in wet places, where it mingles with its fellow traveller, red maple. Indian basketmakers tend to closely guard the location of prime black ash harvesting sites, simply because of their rarity. Not every black ash is a potential basket tree. Basketmakers want straight trees with open growth rings. The trees are felled, then beaten to tease the growth rings apart. Perhaps one in a hundred trees is deemed suitable for basket material.

William Livingston, a professor of forestry at the University of Maine, said the better basket trees tend not to grow in swampy areas, but on richer ground. It’s always been a relatively uncommon tree, he said.

For the past two years, Livingston has been heading a project to find more stands of black ash, to serve as sort of a backup in case known stands are killed by the emerald ash borer. So far he and his students, using aerial photographs and boots on the ground, have found about 30 new sites.

Livingston doesn’t think that the borer will wipe ash species from the face of the earth. “It’s probably going to be very similar to Dutch elm disease. The urban ash are going to be wiped out, but the ash in natural forests, we’re still going to have populations there like we still have elm populations. Some black ash will escape,” he said.

One question is, how many. Another one is . . . can anything halt the beetle’s voracious march across North America.

Insecticides can keep individual trees alive, but are impractical to apply in forests. Biocontrols seem to be the only possible long-term solution. Research has focused on a handful of native and non-native non-stinging Emerald ash borer larva (Photo: S. Ellis, APHIS)wasp species that prey on the beetle, and on a fungal pathogen that appears to affect it. So far there appears to be no magic bullet.

“It’s my understanding that they’ve got a couple that look very promising,” said Struble. “I’ve gotten some anecdotal stuff that they’ve gotten 60 percent parasitism. That’s huge. We don’t need 100 percent  and I can’t say in good faith that there’s a high probability of that in the near future. But if we get some control that is good.”

Livingston agrees that, if there is to be a reprieve, it will come because of biocontrols. But even if an effective predator or parasite or infectious agent that attacks the borer isn’t found right away, there’s still some time, he said. While Livingston too is of the opinion that emerald ash borer will find its way to Maine, he said it will take time for the infestation to develop. It won’t be total devastation overnight.

“It’s not going to be killing all the ash tomorrow,” he said. “People don’t need to panic and cut their ash, we’re going to have time to deal with this in a reasonable manner.”

Research has shown that an ash borer infestation unfolds over many years. In the first couple of years infected trees show little sign of damage -- hence Dave Struble’s worry that Maine could already have an infestation but not know it. In the third year dieback starts. By the fourth, the tree is usually dead. In a given region many of Threatened? An emerging basketmaker at an MIBA workshop. (Photo: MIBA)the trees die at the same time. This poses a particular headache for cities, where municipal budgets are often strained because of the need to remove many dead trees at once. Because of the borer’s egg-laying capacity, population growth can be exponential, with the population building to huge proportions and newly emerged beetles flying out to infect nearby stands. Gradually all those infested areas merge into one and all the ash are dead.

Indian basketmakers are already helping Livingston in his search for new stands of black ash.

Secord said tribal basketmakers are also looking at other options:  using other natural materials for their craft, such as basswood, also a traditional Wabanaki basket material, and sweetgrass, another traditional material. And even using oak, a common basket material, just not a traditional one in Maine.

She said there’s also been talk about saving genetic material, starting a seed bank, for instance. The borer, unfortunately, tends to kill young ashes before they can set seed. And, perhaps, stockpiling cut basket trees is a possibility, she said. The old basketmakers often did this, Secord said, sinking cut ash bolts in ponds for a year or two before splitting it. Ash that has dried can’t be used for basketry, but ash that’s kept wet can be.

“It’s great to have multiple options,” said Livingston. The question is: are there people to do the work and money to pay for it.

Struble said he’s hoping that, when the beetle does show up in Maine, it’s in only one area, perhaps a single county that can be easily quarantined without landowners in surrounding counties having their ability to market ash restricted.

“Right now we’re buying time” with quarantines, said Struble. Eradication of the beetle, like most imported invasive species, isn’t in the cards. 

“There are pests where eradication has shown some kind of success -- Asian long-horned beetle, for instance. It’s not working with emerald ash borer. We have too big an infestation now to eradicate unless you had some wildly successful biocontrol that hunted the beetle anywhere it was on the landscape. What we are doing is buying time,” Struble said. 

“The question is, are we using the time that we’ve bought well? If researchers are coming up with biocontrols; if they’re breeding a resistant ash; if you’re allowing people to salvage a very valuable resource before it’s degraded; if you’re saving the genome before it’s wiped out. Those are legitimate reasons to buy time. If you’re not going to do that, it’s a waste of effort. We have to use the time we’re buying well.”

Joe Rankin is a forestry writer and beekeeper. He has covered Maine’s forest products industry for more than 30 years.