Got Nature? Blog

Tree of Heaven Seedling

Tree-of-heaven seedling

​Invasive plant species threaten many habitats including forests across Indiana. The introduced Asian tree-of-heaven (Ailanthus altissima) is one of these aggressive and troublesome invaders. Tree-of-heaven grows very quickly on a wide variety of sites from seed and sprouts and can rapidly out-compete native trees and shrubs. There are areas in Indiana forests already dominated by this unwelcome invader. Controlling large infestations of this tree can be very expensive and even dangerous. The sap and wet sawdust of this tree can trigger an allergic reaction in some people.

There is some hope on the horizon. Research work done by the U.S. Forest Service and universities in Pennsylvania and Ohio has identified a fungus that can kill tree-of-heaven and has minimal or no impact on surrounding plants. Verticillium nonalfalfae or Ailanthus verticillium wilt is a soil fungus that has been identified so far in Pennsylvania and Ohio that can rapidly kill large patches of tree-of-heaven. Tests with this naturally occurring soil fungus have shown it to be very effective at killing tree-of-heaven without having significant impacts on surrounding native plants.

This naturally-occurring killer of tree-of-heaven could be an important tool in managing this invasive problem in Indiana. The quickest way to get started with natural bio-control of tree-of-heaven is to locate the fungus here in Indiana. Citizens and resource professionals can help us locate ailanthus verticillium wilt by identifying patches of tree-of-heaven that are being impacted by the fungus. This requires familiarity with the identification of both tree-of-heaven and the symptoms of the wilt disease on the tree.

Tree of Heaven Closeup

Close-up of the “teeth” on the leaves of tree-of-heaven

Tree of Heaven has long, compound leaves resembling sumac or black walnut but possessing small notches or teeth at the base of the leaflets. The plant parts have a very unpleasant burnt nut odor when crushed or bruised. The bark is smooth and grey with light grey or white fissures running vertically in the bark. Twigs are very stout with a light tan spongy pith in the center.

Ailanthus wilt causes rapid death of the tree, often within one season, so look for patches of tree-of-heaven where most trees are showing wilting foliage or are already dead. The mortality will often be radiating out from a central group of dead or dying trees. Trees with wilt will have a yellow to yellow-brown discoloration of the wood directly beneath the bark. Healthy tree-of-heaven will have nearly white wood under the bark. The mortality will almost always be groups of trees, not scattered individuals. Several resources are included below to help you identify tree-of-heaven and ailanthus wilt.

If you encounter what you think is ailanthus wilt in Indiana, please contact:
Lenny Farlee, Hardwood Ecosystem Extension Specialist
Purdue Forestry and Natural Resources
Email: lfarlee@purdue.edu
Phone: 765-494-2153

Joanne Rebbeck, Plant Physiologist
USFS, Northern Research Station
Email: jrebbeck@fs.fed.us
Phone: 740-368-0054

Resources
Tree-of-heaven Images, Center for Invasive Species and Ecosystem Health
Scientists Using Fungi to Stop an Invader​, The Columbus Dispatch
Verticillium nonalfalfae, USDA Forest Service
Invasive Species, Purdue Extension​
The Education Store, Purdue Extension Resource Center (search “invasive”)

Lenny Farlee, Hardwood Ecosystem Extension Specialist
Department of Forestry and Natural Resources, Purdue University

Poison Hemlock

Photo credit: Pedro Tenorio-Lezama, Bugwood.org

Made infamous through the trial of Socrates, Shakespeare’s Hamlet and Macbeth, and several other works of classic literature, poison hemlock is an extremely toxic plant that will pose a risk this summer and should be handled with caution.

Poison hemlock is a biennial plant, meaning that it has a two year lifespan. Last summer, it went through vegetative growth and largely stayed out of sight. This summer, it will produce small white clusters of flowers and will be more likely to catch the attention of animals and people. Poison hemlock is a member of the parsley family and can sometimes be confused with wild carrot. However, its distinguishing feature is its hairless hollow stalks with purple blotches. If you see these, be careful!

The biggest risk with poison hemlock is ingestion. Lethal doses are fairly small, so it is important for animal owners or parents of young children to identify it in their area and remove it if possible. The toxins can also be absorbed through the skin and lungs, so be sure to wear gloves and a mask when handling these plants.

Symptoms of hemlock poisoning include dilation of the pupils, weakening or slowing pulse, blue coloration around the mouth and eventually paralysis of the central nervous system and muscles leading to death. Quick treatment can reverse the effects, so act quickly.

Resources
Invasive Plant Species Fact Sheets: Poison Hemlock, The Education Store, Purdue Extension Resource Center
Recognizing and Managing Poison Hemlock, Purdue Landscape Report
Poison Hemlock, Pest & Crop Newsletter, Purdue Extension – Entomology
Hemlock Woolly Adelgid: Distribution Update, Purdue Landscape Report
What are Invasive Species and Why Should I Care?, Purdue Extension – Forestry and Natural Resources (FNR)
Indiana Invasive Species Council
Report INvasive, Purdue Extension & Indiana Invasive Species Council
Poison Hemlock (Conium maculatum), United States Department of Agriculture (USDA)

Purdue Extension

Commercial Greenhouse and Nursery Production: Alternative Options for Invasive Landscape Plants​Ornamental plants provide many environmental and ecological benefits to landscapes and urban areas. They can be aesthetically pleasing, reduce stormwater runoff, lower carbon dioxide and pollutants, alleviate the urban “heat island” effect and provide habitats to pollinators, birds and mammals. And in the last 20 years, consumers and the general public have become much more aware of these benefits. The urban environment is different than most locations in a plant’s native range. It is an ecosystem unlike any other due to extreme environmental pressures, so landscapers and homeowners must use a wide range of plant material that will survive in these unique and often harsh environments. Horticulturalists have continued to discover and introduce plants to broaden the plant palette. Unfortunately, a few of these landscape species can escape into wild areas and create ecological problems in unintended areas such as forests and woodlands. In Indiana, a few frequently used landscape plant species have invaded these natural areas and are displacing native species.

For these reasons, the green industry must begin to produce and use different landscape plants that can replace the invasive species. This publication lists potential alternatives to some of the most notorious and damaging invasive plants in Indiana.

For a free download of the full publication, visit Commercial Greenhouse and Nursery Production: Alternative Options for Invasive Landscape Plants.

Resources
Native Trees of the Midwest, The Education Store
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
FNR/Purdue Extension YouTube Video Playlist, Asian Bush Honeysuckle, Burning Bush and Multiflora Rose
Purdue Plant & Pest Diagnostic Laboratory (PPDL) (Send in samples or photos)

Lindsey Purcell​, Chapter Executive Director/Certificate Liaison
Indiana Arborist Association

Rosie Lerner, Horticulturist
Retired

Posted on March 17th, 2015 in Invasive Plant Species | No Comments »

​Garlic Mustard PlantSustainable Forests Roundtable will be hosting a Invasive Plant Best Management Practices webinar. Best Management Practices (BMP) help you identify effective and realistic practices that can be integrated into any behavior. Whether you’re a gardener, a landowner, a forester or a logger, the movement of invasive species is always a concern. A BMP can be as simple as cleaning your shoes or as complex as pressure washing your bulldozer. Regardless of your practice, the goal is always to minimize the spread of invasive species.

Learn how to create best management practices that help identify and minimize the spread of invasive species. The presenters for the webinar are Bernie Williams, Invasive Plants and Earthworms Outreach Specialist, Wisconsin Department of Natural Resources; Brad Herrick, Ecologist and Research Manager, University of Wisconsin Arboretum; and Judy Kingsbury, Volunteer Coordinator, University of Wisconsin Arboretum.

Who: Sustainable Forests Roundtable
What: Invasive Plant Best Management Practices webinar
Where: On the Sustainable Forests Roundtable website
When: March 24, 2015, 1 pm US/Eastern
Details: No registration is required. View the Sustainable Forests Roundtable website to see how to join the webinar.

Resources
​Got Nature? Blog (Click on “Invasive Plant Species”), Department of Forestry and Natural Resources (FNR)
Invasive Plants, Purdue Agriculture Weed Science
Invasive Plant Species, Indiana Department of Natural Resources

Sustainable Forests Roundtable
Partners include: North Carolina State University’s Extension Forest Resources, Texas AgriLife Extension Service and the USDA Natural Resources Conservation Service.

Posted on August 14th, 2014 in Forestry, How To, Invasive Plant Species, Podcasts | No Comments »
Lenny Farlee

Lenny Farlee pointing out invasive Jet Bead at a Purdue Extension invasive plant training program.

If you have ever taken a walk through a forest, a woodland or a park, then you have likely encountered exotics plants. What may be difficult to distinguish, however, is whether or not those exotic plants are invasive. Unfortunately, most of us think that if it’s green, it’s good, but being green could be misleading. Invasive exotic plants are consuming growing space at an alarming rate and replacing our native species. These changes in plant species can have dramatic impacts, both economically and ecologically, to landowners and the ecosystem. Invasive species are such a problem that we are devoting an entire Podcast series to this topic.

In Part I of the Got Nature? Podcast mini-series on Invasive species, our host, Rod Williams, will be interviewing Lenny Farlee, an extension forester with the Hardwood Tree Improvement and Regeneration Center at Purdue University. Lenny will be the first expert in a series of podcasts devoted to the topic of invasive species, both terrestrial and aquatic. Lenny will be introducing our listeners to the topic of invasive species, identifying which species pose the greatest threats to the woodlands within Indiana and discussing the ecological and economic impacts that invasive plants pose to landowners. This podcast will also highlight methods that can be used to manage woodlands infested with invasive plants.

Resources
Midwest Invasive Plant Network
Indiana “Most Unwanted” Invasive Plant Pests
Purdue Extension Agriculture & Natural Resources
iTunes-Got Nature?
Got Nature? Podcasts

Lenny Farlee, Sustaining Hardwood Extension Specialist
Department of Forestry and Natural Resources, Purdue University

Rod Williams, Associate Professor of Wildlife Science
Department of Forestry and Natural Resources, Purdue University

Posted on June 17th, 2014 in Invasive Plant Species, Plants | No Comments »

According to the USDA Forest Service, an invasive species is defined as “a species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.” Invasive species, along with habitat loss and pollution, are the most severe threats to biodiversity and ecosystem function. Why are they such a problem? One factor that my colleague, Lenny Farlee, points to is that people don’t know they have a problem. That is, they are all around us, and most folks don’t even know it. People must first be able to recognize invasive species from non-invasive species. One of the more recent invaders is tree-of-heaven (Ailanthus altissima).

Tree-of-heaven leaflet

Figure 1. Tree-of-heaven have pinnately compound leaves with 11 to 27 leaflets. Each leaflet has one to several glandular teeth near the base. These are lacking on other trees and shrubs.

Don’t be fooled by the name. They are far from heaven for us. It’s actually been around for a couple hundred years. However, only over the past 10-20 years ​has it really begun to expand its range. This pattern is very typical of invasive species invasion. Mid-summer is one of the best times to identify and control this tree. Ohio State produced a publication on control methods, and this is linked at the end of this article. I want to focus on identification here.

Tree-of-heaven

Figure 2. The fruit of tree-of-heaven are winged samaras. They can be green, red or brown in color. Numerous clusters of fruit are easily observed on tree-of-heaven during the summer.

Tree-of-heaven may be confused with similar-sized sumacs or even black walnut to the untrained eye. Because tree-of-heaven can grow very rapidly, they will often have several feet between branching along the main trunk. Some have also described the strong odor from tree-of-heaven similar to rotting peanuts. For most folks, the leaflets and fruit are the easiest features to go by. Each leaflet has one or more glandular lobes or teeth near the base. This is the best feature to differentiate it from similar species of similar size. On older trees, numerous fruit clusters will begin to form towards the end of June and will be present throughout most of July or longer. Black walnuts and other native trees with compound leaves lack these seed clusters.

Resources
Controlling Non-Native Invasive Plants in Ohio Forests: Ailanthus
Indiana Invasive Species Council

Dr. Brian MacGowan, Extension Wildlife Specialist
Department of Forestry & Natural Resources, Purdue University

Posted on April 23rd, 2014 in Alert, Forestry, Invasive Plant Species | No Comments »

Early spring brings the emergence of new life in the forest. Unfortunately, not all that life actually belongs there. Several invasive plants are encroaching on woodlands and crowding out the desirable native plants we enjoy and wildlife depend upon for food and shelter. One of the characteristics of some invasive plants is early leaf emergence and growth, which allows us to scout for their presence more easily, while native species are still waking up from winter. Two species that start growing very early in the spring are garlic mustard and Asian bush honeysuckles. Both plants are rapidly greening up and growing as I speak. Look for the kidney to heart shaped leaves of garlic mustard on the forest floor. This biennial will soon be sending up flower stalks from the second season plants that will have white four-petaled flowers. The flower stalks can be up to three feet tall or more depending on the health of the plant and the quality of the growing site.

Garlic mustard

Early spring leaves of garlic mustard.

Asian bush honeysuckle is a medium to large bush that also inhabits the forest understory and edge or disturbed areas. Leaves and twigs area arranged opposite each other. If you slice the stems open, they are hollow inside with fuzzy brown or tan lining​. Flowers are yellow, white or even pinkish and tube-shaped. The fine twigs and stems have a light tan or gray-tan color. Leaves are rapidly expanding now, so they will be easily detected until our native plants catch up with leaf cover.

Asian bush honeysuckle

Early growth of Asian bush honeysuckle.

Controlling these plants helps native plants continue to thrive and provide habitat for our wildlife. Garlic mustard can be pulled from moist soil. If seed pods are present, remove the plants from the area and burn or bury them. Foliar herbicides like glyphosate products may be used to spray garlic mustard. If the plants have already set seed pods, the seed may become viable even if the plant has been sprayed, so removal may be the only effective treatment at that time.

Asian bush honeysuckle can be controlled in several ways, depending on the size of the plants. Small plants can be pulled from moist soil. Foliar sprays with herbicides like glyphosate can be effective. Large bushes may be cut and the stumps treated with a brush-killing herbicide. For any herbicide application, read and follow label directions.

Purdue University has invasive species information resources at FNR Extension and Indiana’s ‘Most Unwanted’ Invasive Plant Pests/Indiana Cooperative Agricultural Pest Survey (CAPS) Program.

Lenny Farlee, Sustaining Hardwood Extension Specialist
Hardwood Tree Improvement and Regeneration Center (HTIRC)
Forestry and Natural Resources, Purdue University

The Nature of Teaching website.As teachers prepare their lessons for the fall, The Nature of Teaching is a great website to visit for science-based resources. Teachers can find free lesson plans, printable, posters, a photo library, information on upcoming workshops and more. You will find on the website tabs titled “Formal Curriculum” and “Informal Curriculum.” The Nature of Teaching also offers professional development workshops for teachers focused on science, the environment, and getting students connected with nature.

​These organized lesson plans meet several K-5 Science and Math Academic Standards along with three 9-12 Natural Resource Management Academic Standards.

Wildlife curriculum include:

  • Animal Diversity and Tracking
  • Discovering the Watershed: Effects on Water Quality
  • Common Indiana Mammals: Natural History and Identification
  • Invasive Plants: Impact on Environment and People
  • Hellbenders Rock! Natural History and Conservation of the Eastern Hellbender

Food Waste curriculum include:

  • Food Waste and Natural Resources
  • What a Waste of Food!
  • Food Waste and The Environment
  • Food Waste Solutions
  • Transporting Food Waste

Health & Wellness curriculum include:

  • Unit 1 Benefits of Connecting with Nature
  • Unit 2 Gardening Station
  • Unit 3 Tree Talk Station

Other resources:

Contact The Nature of Teaching team if you have any questions regarding workshops, certifications and curriculum.

The Nature of Teaching​, Purdue Extension

Posted on September 21st, 2012 in Forestry, Invasive Plant Species | No Comments »
blacklocust

Black locust
Credit: Richard Webb, Bugwood.org

I recently received an email from a private landowner:

I had a question for you about Black Locust and the Indiana’s Most Unwanted website. I saw Black Locust is listed on there even though another site says it’s native range includes Indiana. I see invasives.org mentions that it can become invasive in prairie and savanna areas. Can you shed a little light on this? I mean, I see it all over but not to the point of other invasives. Is it invasive in woodlands or just open areas? What is the deal?

Also on the Most Unwanted site, I see a lot of the plants say something like “Note – do not buy, sell or plant Asian bush honeysuckles,” but Black Locust does not. Any idea why? This site doesn’t really give a good feel for their classification as invasive, aggressive, noxious, etc. I didn’t know if there was a better site that could give me an idea for that or not as well.

I guess mainly I’m confused since it’s a native, it wouldn’t seem to me that it should be an invasive.

Thank you for your assistance.

This landowner has some really good questions regarding a tree species that is found across the state of Indiana. Now I have been talking on and off with this landowner about various species over the past year or so as he is fighting the good fight and trying to eliminate invasive and non-native species from his property but is also attempting to re-vegetate with native species. This is not the first time that I have had this discussion, so I thought why not answer his question so that others could also get to the information?

The websites this landowner provided are all great sites with tons of information for a bunch of different species. So inevitably when you get lots of great information about one species, it is easy to skip or unintentionally omit some details for other species. I hope the folks behind sites like these continue to build these great sources of information, update them with current best management practices and add new species as they become problematic.

Now, onto the questions.
Black locust, Robinia pseudoacacia, is native to the state of Indiana (Deam 1940, Flora of Indiana). However, when we talk about species that are native to the state, they may not be native to the whole state. With the settlement of the Midwest, it is thought that European settlers brought black locust with them as they traveled due to its fast growth, wood quality and even perhaps for its nitrogen-fixing capabilities. There are numerous species which may be native to one part of the state but not others. One example of this, bald cypress, Taxodium distichum, is native to southwestern portions of the state where bald cypress swamps can be found, but it wasn’t historically found in the dunes of northwestern Indiana. A map of its native range can be found here.

I commonly have the discussion of the “official definitions” of invasive, non-native, exotic, aggressive, noxious, weed, etc., with folks. These definitions are an area of much debate in scientific literature and among professionals that regularly work to manage these species. It is my belief that “invasive” species can be both exotic (not from the geographical region in question) and native (belonging to the geographical region in question), just like exotic species don’t have to be invasive (grow and spread aggressively). Noxious plants (“any plant, or plant product, that can directly or indirectly injure or cause damage to….”) can fit into each of those descriptions, and then of course, there is the definition of a weed…a plant that grows in an area that we don’t want it to. Everyone has their own opinion though, right?

There are many places to look up species-specific information on a state-to-state as well as a county-to-county level. For example, I like to use two websites: www.bonap.org and plants.usda.gov. Unfortunately, there are so many species and so many records that are needed to update these types of databases that they may not accurately represent what is truly out there. Plus there are the differences between historical records and current records which can bring about another debate.

So to wrap this thing up and provide short answers to Scott’s questions:

Q: Is black locust native to the state?
A: Yes.

Q: Can black locust be invasive in prairie and savanna habitats?
A: Absolutely! It spreads aggressively into these environments, especially in the absence of disturbance (another topic for another posting…).

Q: Is it invasive in woodlands or just open areas or what is the deal?
A: Mostly in open areas. It doesn’t tolerate high shade very well.

Q: Any idea why websites don’t suggest to “buy, sell or plant” even though they list it as an invasive (paraphrased)?
A: No, I don’t. That said, I am not familiar with where to buy seedlings, but then again, I don’t have an interest in planting them!

In closing, would I plant black locust? No, I wouldn’t unless I intended to use the trees as a crop. Black locust makes great firewood and great fence posts, and the flowers taste pretty good in the spring. However, they can grow and spread quite aggressively through root suckers as well as by seed. Commonly the little patch of a few trees turns into acres and acres!

Resources:
ID That Tree – Video Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
ID That Tree of Indiana: Black Locust, Purdue Extension – FNR blog post
Purdue Arboretum Explorer
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Report Invasive, Purdue Extension
101 Trees in Indiana, Amazon
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
An Introduction to Trees of Indiana, The Education Store
Professional Forester, Indiana Forestry Woodland Owners Association
Forest Improvement Handbook, The Education Store
Find an Arborist, International Society of Arboriculture

Lenny Farlee, Extension Forester
Hardwood Tree Improvement and Regeneration Center
Purdue Department of Forestry & Natural Resources

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