Ailanthus Wilt Research Study Video Podcast Transcript

CHANCEY: Hi, I’m Gary Chancey, public affairs officer for the Wayne National Forest.

Today’s show is focusing on ailanthus, a non-native invasive tree that is a serious threat to plant community health and diversity in Southeast Ohio, including the Wayne National Forest and adjacent landowners.  On the Athens Ranger District’s Marietta Unit, they have thousands of female ailanthus trees spread out over thousands of acres.  To help us understand what ailanthus is and to share news about an upcoming research project, we have with us today Wayne National Forest botanist Sierra Patterson, and Joanne Rebbeck, who is a researcher with the USDA Forest Service’s Northern Research Station located in Delaware, Ohio.

Joanne, first many of listeners are probably wondering, what is ailanthus?

REBBECK:  Ailanthus is a non-native tree.  It’s native to China, brought here back in the late 1700s.  It is a fast-growing tree.  It can grow up to maybe three or four feet in a year.  Its growth rate is much quicker than our native trees.  It produces large leaves that can shade out other trees, but almost looks like a walnut tree is probably the closest thing that it looks like.

CHANCEY: So when you take a look at the bark, what does that look like? People out in the woods are looking at trees, what would you compare it to?

REBBECK:  I often tell people it’s pretty non-descript. Depending on what age it is, when it’s really large, it’s kind of this smooth, grayish color bark.  I wouldn’t quite say elephant skin, but it could be confused, maybe, with a beech bark.  When it’s younger, it almost has like a diamond-shaped pattern on it, and I tell people it kind of reminds me of alligator skin.

CHANCEY: But how did it make its way to the United States, and better yet, here in Ohio?

REBBECK:  It went from China to Europe, and then a Philadelphia gardener found it, brought it, and planted it in his garden in the 1780s. People got excited about it. It’s common name is tree-of-heaven.  Tree-of-heaven is because it’s growing up in the skies to the heavens.

CHANCEY: Why is it such a bad tree?  How is it impacting our forest today.

REBBECK:  Well, the problem is because it is not native, it escapes all the predators, the pathogens, all the insects, diseases that attack our native trees.  So it’s almost like a super-healthy, fast-growing organism that doesn’t have any checks and balances, like our native trees.  So it will grow and overshadow all the native trees who have to deal with insects or deer browsing on them, those kinds of things. Chemicals go and can leach out into the soil and inhibit other native plants from growing – anything from small herbs, plants like that, to young tree seedlings.

CHANCEY:  Is it true that ailanthus has the potential to replace oak and other native tree species?

REBBECK:  Yes.  In my observations and my research over the years studying ailanthus, that’s actually how I first started working on it because I saw that after a disturbance, say, in an oak forest, whether it be by either a harvesting, or ice damage, or a wind event, or the native trees died from a disease, insect defoliation, it the soil’s disturbed, the ailanthus comes in and because it grows so quickly and because it produces lots and lots of seeds, it can take over an area and outgrow all the native vegetation.

CHANCEY: So here on the Wayne, it’s probably got, what, a 60 year head start on us, pretty much – 60 to 80 years?

REBBECK:  Yes, that is correct.  What we’re seeing is, although I haven’t tested this yet, a lot of our public lands, whether it be on the Wayne, adjoining property, had been utilized for agriculture, for extraction of coal, of gas and oil, timber harvesting, they were there and present in these landscapes.  And as the lands reverted back to forest, they were able to persist, and now, as we have continued or different disturbances, they’re there and kind of poised and ready to take advantage of any new open spaces.

CHANCEY:  Thanks, Joanne.  Sierra, as the Wayne National Forest botanist, tell us how ailanthus is actually impacting the Wayne National Forest.

PATTERSON:  It can grow and replace native species. Our priorities are to manage our native ecosystems, which are our oak, hickory forests, and we’re also managing our wildlife species that we have in Southeast Ohio.  So if ailanthus comes and replaces these native tree species, we’re replacing a food source for our native wildlife, we’re replacing our native tree species.

CHANCEY: Yes, I understand you’ve been doing a lot of mapping since about, what, 2011 over the forest to actually find out exactly how much ailanthus we have on the landscape.

PATTERSON:  So this is in collaboration with the Ohio Department of Natural Resources, the Division of Forestry. And the protocol is to, in the wintertime, map ailanthus.  Female ailanthus trees are visible from a helicopter – the seeds persist on the trees. So across the Wayne National Forest and the Marietta Unit, we have surveyed 120,000 acres, and on these acres, 3,000 female trees have been mapped. So this is only half, roughly, the amount of trees that potentially could be found because there’s also male ailanthus trees.  On private lands we estimate there’s about, in the Marietta Unit, 1200 female trees – ailanthus trees – across about 80,000 acres of private land.

CHANCEY: Joanne, in talking more about the ailanthus tree, how does it spread?

REBBECK:  It has two ways that it can spread.  The first is it produces lots of root sprouts. They can travel several hundreds of feet away from the original tree and sprout up, and they form almost like a dense mat or thicket of pure ailanthus, so that excludes other species from taking hold. And then the second is by its production of seeds.  It produces huge, huge numbers of seeds. There are male and female ailanthus trees.  The females produce 300,000 seeds per tree – just clumps and clumps on the trees, and you’ll often see those along the Ohio River, major highways and things. So then you have these wind events and there’s no other leaves out on the other trees, which doesn’t restrict its movement, so they can get blown by the wind, they can hit the ground and blow on the soil, they can move down hills, they can move in water, even in streams and creeks.

CHANCEY:  In the springtime, they’re like normally one of the last ones to bud out, too, right?

REBBECK:  Yeah, and that’s another easy way to identify them.

CHANCEY: Thank you sharing a little bit about ailanthus, both of you, and the impact it’s making on Wayne National Forest and other private landowners around the area.  This year you are collaborating with us to begin a field trial of a native fungus as a means of killing ailanthus trees, and it’s cost effective and does not use chemicals.  How confident are you that the native fungus will kill ailanthus trees here on the Wayne National Forest?

REBBECK:  Based on research that I’ve done previously, both in the lab in the greenhouse under controlled conditions, I’ve done some preliminary trial treatments.  In other parts of Ohio, I have actually seen how this is very effective at killing both very small ailanthus and large, adult trees.  The bulk of this demonstrating that it is effective against ailanthus was done in Pennsylvania, where the fungus, this native, was first detected in Pennsylvania, killing large areas of ailanthus, and exclusively ailanthus.  It’s very selective to kill ailanthus.

CHANCEY:  And starting in June you’ll actually start to introduce the native fungus. REBBECK:  Yes.  The idea is this is one of a number of study areas within Southeastern

Ohio where we’re going to inoculate.  Instead of using an herbicide treatment where you’re making a cut in the base of the ailanthus tree, and instead of squirting an herbicide, we culture the fungus in the lab, and then we take those spores and put them in a water solution, and basically make a cut and then squirt – we just use a spray bottle and squirt the spores into that injection. And it goes and moves through the water system, through the xylem tissue of the tree and basically clogs up the plumbing of the tree.  Over the course of a growing season, typically, the tree will die.

CHANCEY: And you may seem some wilt within two weeks after – the tree?

REBBECK:  Yes, so think about this fast growing tree plugging away, growing very rapidly, and its pipes are clogged so that initial response with early as two weeks, it starts to wilt.

CHANCEY:  Now the areas, the actual plots that we’re talking about are in Washington County, treatments will begin in Grandview, Independence, and Newport townships. Joanne, you said earlier that the fungus is native to Ohio. Could you expand that for us?

REBBECK:  We found the fungus in June of 2012 in Pike County in a forested area, with the help of some foresters that were out in the field and saw the symptoms of the wilting leaves.  And most recently, in 2014, we found it again about five miles away from that first infestation.  And then in September of 2014, we found it just a county north of the Marietta District in Monroe County. So it’s out in the environment already.

CHANCEY:  Now, Washington county, that’s your primary area there, could you expand a little bit about the research plot areas?

REBBECK: The plots – we actually selected those last summer. They are about 66 feet wide and 164 feet long. So those are within some, I would say, more remote areas of the forest.

CHANCEY:  More than 71 species, I understand, of native Ohio trees have been tested for sensitivity to the fungus. Could you tell us what species have shown some sensitivity to it?

REBBECK:  The work actually – this work began over in Pennsylvania with Penn State scientists.  I have expanded on that list, looking at native seed sources of our oak species, hickory species.  But those that are sensitive, show some sensitivity, included striped maple, which actually is not found in Southeastern Ohio.  Sumac, and devil’s walking stick also showed some limited sensitivity.

CHANCEY: Now, once you have released the native fungus into the trees, what is the next step for the study?

REBBECK:  Part of the research is to be monitoring how fast it spreads, as well as confirming that no additional species are impacted by the fungus.  We’ve been monitoring that at the other sites where it was naturally found in Pike County, and are going to begin to look in Monroe County as well.

CHANCEY: While this a small-scale research project, what is the rate of spread?

REBBECK: We have seen, both here in Ohio and in Pennsylvania, the rate of spread could be from 200 to 400 feet a year, but so much of that depends on how much ailanthus is currently at the site. So if there’s scattered trees, since it moves from root to root, the intermingling of the healthy trees with the infected trees, the fungus can be transferred to healthy trees that way, where it also lives in the soil. So depending on how many ailanthus trees, it could move faster.  But it’s all based on these natural infections.

CHANCEY: Sierra, what has the Wayne National Forest done to kill the ailanthus tree?

PATTERSON:  Well, we’ve had a pretty aggressive herbicide program to treat these ailanthus trees on Wayne National Forest, so we’ve used this hack and squirt method which is basically cutting the bole of the tree with a machete or a hatchet and then spraying some highly concentrated herbicide into the boles of the trees. And we’ve accomplished quite a few thousand acres on the Wayne National Forest in the past five years.

CHANCEY: So it’s very effective, I understand.  I saw some of that last fall.  It’s very costly.

PATTERSON:  Yeah, I think we treated about 1,600 acres of ailanthus over in the Marietta Unit with the partnership and with the National Wild Turkey Federation, and that roughly was about $100,000 to do 1,600 acres, so it is quite costly to use herbicide.

CHANCEY:  In addition to the research project that Joanne’s heading up, what is our treatment plans for 2015?

PATTERSON:  We’re going to be treating on the Wayne 1,500 acres, at least, of ailanthus, which costs – it equates to about $150,000. Beyond that we have technicians that will be on the ground treating, retreating areas and surveying areas that have been treated of ailanthus.  In terms of acreage there, we’ll probably get a few hundred acres of ailanthus on the Wayne with our crew that we have for this summer.

CHANCEY: The aerial flights will continue this fall. PATTERSON:  They will be continuing this fall and winter.CHANCEY: Right. And that will be our last question for today’s show.  Today we have been focusing on ailanthus, a non-native invasive tree that is a serious threat to plant community health and diversity in Southeast Ohio, including the Wayne National Forest and adjacent landowners.

Our guest has been Wayne National Forest botanist Sierra Patterson, and Joanne Rebbeck, who is a researcher with the USDA Forest Service’s Northern Research Station located in Delaware, Ohio.  We’ll look forward to hearing about the progress of the research project in the near future.


Until next time, I’m Gary Chancey.