Purdue University - Extension - Forestry and Natural Resources
Got Nature? Blog
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.
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
We all know that trees help to improve our air quality. Absorbing toxins, reducing CO2 levels and providing shade are well-known benefits of trees, and many initiatives are in place to increase urban forested areas. However, there is an interesting fact to consider. According to the U.S. EPA, the average American spends 90% of their time indoors, where those benefits of outdoor trees aren’t nearly as impacting. In fact, pollutants are estimated to be two to five times higher indoors than outdoors and account for several billion dollars of health costs nationally. Indoor air needs to be cleaned too. This is the problem that Purdue’s BioWall team hopes to solve.
The project began in 2009 as part of a fully self-sustainable house called the INhome. In 2011, INhome competed against 20 other teams in the United States Department of Energy’s Solar Decathlon and scored second place, largely due to its most distinguishable feature, the BioWall. The BioWall was integrated into the return duct of INhome’s air conditioning system, filtering the air inside the home through the roots of golden pothos and other species of ivy that are known to have a strong effect on air quality.
Today, the BioWall team is in the process of testing out an updated version of the BioWall. Prototype designs are being tested to improve the air cleaning qualities as well as the lifespan of the plants. Bypass tubes are being implemented to lessen the amount of air passing over the plants’ roots, allowing them to dry out slower and live longer. Eventually, the team would like to put out a consumer version in the next few years for about $2,000. It’s a lofty goal, but the team believes they can succeed and bring affordable and self-sustaining indoor air cleanliness to homes around the world.
For more information, check out the BioWall team’s website.
Resources
BioWall, Purdue University
Office of University Sustainability, Purdue University
Questions About Your Community: Indoor Air, United States Environmental Protection Agency
William Hutzel, Professor of Mechanical Engineering Technology
Purdue University
Photo credit: Colin Hutton
An often overlooked part of the ecosystem responsible for our food and environmental health are the pollinators. This group of animals move pollen from flower to flower, fertilizing seeds, fruits and vegetables. Pollinators include honey bees, native bees, moths, beetles, birds and bats, and they are struggling. 40% of honey bee colonies have been lost in the last year, and in the past two decades, over 90% of Monarch butterflies have disappeared.
After noticing this sharp decline, large efforts are starting to take place to restore the pollinator population. The Pollinator Partnership has created a Pollinator Week every year from June 15-21 where the pollinator’s importance is highlighted through local events. The White House has announced a National Strategy to Promote Pollinator Health in hopes to return the pollinator population to a sustainable level. In Norway, a connected network of honeybee habitats dubbed the Bee Highway was created. At the large scale, many initiatives are starting to form, but it is important to know that we can also be helpful on an individual level.
Our gardens and landscapes are the homes of many pollinators, providing the food, water and shelter that they need. When planting a garden or landscape, it is important to take this into consideration and follow a few simple guidelines. For an adequate food supply, aim for at least three flower species in bloom at a time. For shelter, pollinators can benefit from a break from the wind and sun provided by plants, fences and other structures. Finally, pesticides should be limited and used in a controlled way. Pick spray instead of dust-based pesticide. Try to use it only when necessary, follow all label directions and spray only in the early morning or at dusk when pollinators are less active. Keep these guidelines in mind, and your garden or landscape will be an attractive home for pollinators!
For more information, please check out the June column of Purdue Yard & Garden News.
Resources
Gardening for Pollinators, Purdue Yard & Garden News
News Columns & Podcasts, Purdue Agriculture
How to Minimize Pesticide Damage of Honey Bees, The Education Store
Honey Bees, Indiana Department of Natural Resources
Pollinator Partnership
B. Rosie Lerner
Extension Consumer Horticulturist, Purdue Extension
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)
Photo: Tom Campbell
Mushrooms are strange forms of life. Some can kill you within hours, some are psychedelic hallucinogens and others are just good on a pizza. There are estimated to be six to 20 times more species of fungi than plants, and a lot of them are still shrouded in mystery. Since the time of Carl Linnaeus in the 1700s, we have been searching for answers in the fungi kingdom, and recently, we just found a big one in the shape of an evolutionary mapping dubbed the “tree of life.”
Using collections of preserved fungal specimens called fungaria from Purdue’s Arthur Fungarium and Kew’s Fungarium in the Royal Botanic Gardens, two of the biggest and most important fungi collections in the world, mycologists like Catherine Aime were able to study well over 100 years’ worth of preserved specimens and apply modern DNA technology to piece together genomes and discover new connections linking mushroom species. This “tree of life” is the clearest and most comprehensive mapping to date of the evolutionary history of fungi.
Aime says that this study reinforces the importance of fungaria as we advance in the genomic age. These extensive collections are priceless, containing specimens as far back as some from Darwin himself, and documenting hundreds of thousands of species throughout the years. Some of these species might not exist in the future, and it is essential that we document and preserve them as we learn new ways to use them in the future.
The research paper documenting this ‘tree of life’ was published in the Biological Journal of the Linnean Society and is available for journal subscribers and readers at Purdue.
Read the full article.
Resources
DNA Samples From Purdue, Kew Fungi Collections Provide Key to Mushroom ‘Tree of Life’, Purdue Extension
Arthur Fungarium, Purdue Herbaria
Kew’s Fungarium, Kew Royal Botanic Gardens
Aime Lab, Purdue University Department of Botany and Plant Pathology
Fungi – In a Kingdom All By Themselves, Indiana Department of Natural Resources
Natalie van Hoose, Research News Writer
Purdue Extension
Historically, forests dominated the land of Indiana, covering about 85% of Indiana prior to European contact and settlement. However, now less than 25% of our forested areas remain—and more than 85% of those areas are privately owned.
Urban woodlots are steadily in decline, both in number and size. The development of businesses and residential areas, highway construction and expansion and increases in cropland are all causes of destruction and reduction of these woodlots. When privately owned woodlots drop below 10 acres in size, they receive much less support and can’t qualify for the Classified Forest and Wildlands program through the Indiana Department of Natural Resources, forcing their owners to manage them on their own.
Owners of woodlots of all sizes can help protect and improve them with good management and stewardship practices. Adding trees and other plant life, taking care of diseases and other pests and harvesting products when needed are all great steps towards urban woodlot preservation.
The benefits of urban woodlots don’t just help their owners but the entire community around them. Forested areas reduce the impact of rainfall on land, decreasing flooding, erosion and the removal of topsoil. The quality of water is improved as sediment and pollutants are filtered out. Soil is added as plants decay. Air is improved as plants soak in carbon dioxide and other unwanted chemicals. Trees provide shade and reduce wind speed, reducing the need for burning fuel. And of course, woodlots provide habitats that many animals depend on.
Urban woodlots really are crucial for our environment. As it decreases around us, it is important that we know what we can do to protect and improve what we have left. Owners of private urban woodlots must stay informed to keep their property not only beneficial to them economically, but beneficial to our society as a whole.
For more information, view the free publication download titled Indiana’s Urban Woodlots.
Resources
Indiana’s Urban Woodlots, The Education Store, Purdue Extension Resource Center
Urban Forestry – Got Nature?, Department of Forestry and Natural Resources, Purdue University
The Indiana Woodlot Owner Series, Indiana Department of Natural Resources (IDNR)
Indiana Arborist Association (IAA)
Lindsey Purcell, Chapter Executive Director
Indiana Arborist Association
The focus of forest science is increasingly shifting to the management of forests as complex systems rather than as simple agricultural landscapes—with a much greater appreciation for the interactive ecosystem processes. In addition, now for many forest landowners, the ecological value of their land is at least as important as the economic return. It is, therefore, vital to understand how forest management affects not only timber production, but also the overall function of forested ecosystems.
This new publication, Breeding Birds and Forest Management: the Hardwood Ecosystem Experiment and the Central Hardwoods Region, summarizes the effects of forest management on bird species in the Midwest based on data collected as part of the Hardwood Ecosystem Experiment (HEE) in southern Indiana and other studies. We hope this summary provides a basis for understanding interactions between forest management and forest birds as well as guidelines for bird-friendly forest management in Indiana.
Resources
Hardwood Ecosystem Experiment
Hardwood Tree Improvement and Regeneration Center (HTIRC)
The Education Store, Purdue Extension Resource Center
Article shared in NASF May 15, 2015, E-Newsletter
Lloyd Alter, Managing Editor
TreeHugger.com
As we continue to burn through our nonrenewable resources at an alarming rate, it is important that we never underestimate what we can do with our resources that can be replenished. One of these, wood, is an extremely valuable material but has been underutilized in construction for one big reason: fires. Every so often, a wood structure like the 188-unit apartment complex in Richmond, BC, burned down in 2010 goes up in a blaze and hinders the support of timber construction in a big way. While this is a valid concern, there are several things to consider before abandoning hope. Most of the big building fires covered by the news have been on uncompleted buildings still under construction. This means that fire suppression systems haven’t been installed yet, and oftentimes incomplete floors lacking fire-retardant drywall, or walls of any kind, give the fire huge ventilated areas to spread. This is hardly fair to mark these fires as a failure of wooden construction. In completed buildings, close to 80 percent of fires are contained to the rooms they are started in.
Furthermore, fire damage isn’t limited to wooden buildings. Structures made of concrete, steel or other construction materials can still weaken and collapse under the heat of a fire. In fact, heavy timber resists fire very well, burning slowly and creating a layer of char that helps to preserve the structural integrity of the inside wood.A recent advancement in timber technology to note is Cross-Laminate Timber, or CLT. CLT is made from stacks of industrially dried and fully glue-coated lumber. It is exceptionally strong, multi-purpose and lightweight. Construction using CLT is quick because it is easy to prefabricate and transport. Like heavy timber, CLT produces a layer of char when burned, and when used in construction, engineers factor in this layer and use enough wood to allow charring to form while still maintaining enough internal wood to be structurally sound. Also cosmetically, CLT looks pleasing and can be left exposed, reducing building cost. CLT has been considered the future of wood-based construction and for good reason.
So with some of the negative stigma of wooden construction debunked and the values of timber buildings explained, this leaves the biggest value of it all to think about: renewability. Timber is the only 100% renewable material for building construction. One billion cubic meters of logs are produced each year in North America and Europe alone, creating 200 million cubic meters of engineered timber and done in a careful way so that forests maintain their size. This is enough material to build 150,000 offices a year. Timber also locks up carbon that was absorbed by the tree during its growth, reducing pollution. As we look to the future, we should look to the trees. It’s time for timber construction.
Resources
NASF May 15, 2015 E-Newsletter, National Association of State Foresters
Making the Case for Wood Construction, Treehugger
Timber Offices: The Time Has Come, ARUP
The Education Store, Purdue Extension Resource Center (search “timber”)
What is Cross Laminated Timber? American Wood Council
2014 Indiana Forest Products Price Report and Trend Analysis, Indiana Department of Natural Resources
National Association of State Foresters
Question: I just finished cutting down the last of my backyard oaks due to oak wilt. I have also lost several redbuds due to verticillium wilt. I would like to replant a tree in the spot where the oaks and redbuds were, but I would like some advice on the most resistant tree I can find. I live in Crown Point, IN, primarily clay, on a slope, with heavy brush on my property lines. I know most people would say NEVER plant again once wilt has been detected, but I thought I might ask before giving up (and moving all my shade plants). Do you have information/research on an appropriate and sturdy replacement shade tree?
Response: In general, replanting of oaks in an old oak wilt disease center does not result in disease occurrence in the replanted trees. Root grafts are not thought to form with the dead, diseased oaks. It does not appear that the fungus is transmitted outside the primary phases of transmission: vector-borne via insects (e.g., Nitidulidae) and xylem-limited disease spread via live root grafts of infected trees (MacDonald et al., 2009). This does not mean, of course, that the young oak trees as they grow and age over time are immune to oak wilt; rather, it simply means that oak wilt is not sitting dormant in the soil waiting to attack newly planted or germinated oak seedlings.
Thus, it is only through insect spread from active oak wilt centers in the vicinity that disease would occur in replanted oaks. Healthy oak trees are not susceptible to oak wilt in an infected area. Bur oak, white oak and other members of the white oak family are resistant to the fungus and can be planted in oak wilt centers. For additional prevention measures, plant tree species other than Oaks to guarantee no infection from the disease.
Resources
Diseases in Hardwood Tree Plantings, The Education Store
Tree Installation: Process and Practices, The Education Store
Forest Health Problems Impacting Indiana Forest Resources, Indiana Department of Natural Resources
Lindsey Purcell, Urban Forestry Specialist
Department of Forestry and Natural Resources
Question: Weeping willow, six years old and 9″ diameter. Wet, clay ground and thriving. Suddenly late last summer, I noticed the leaves were dead, and the bark on the trunk was completely loose and falling off. No other trees or shrubs within 50 feet (black walnut, sycamore, maple, rose of sharon) were affected. No obvious sign of insects, boring, trails, worms, etc.
Answer: When a tree starts to lose leaves, especially in the spring when they should be expanding for the new growing season, it can be puzzling. Often, this is a sign of troubles which can be caused by biotic or abiotic issues but not always a major cause for alarm. The dropping leaves can be a symptom of foliar diseases which weakens the tree, or it could be the result of an insect pest feeding on the petioles of the leaves. There are many pests which can cause leaf drop.
Another possible cause is the response to abiotic disorders which is typically a complex of issues. Leaf drop can occur on trees that have been exposed to prolonged wetness in heavy, clay soils. Some tree species like wet soils but not prolonged wetness without drainage. If trees are exposed to continual wetness, their roots can become diseased and cause the leaf drop. Additionally, it has been noted that trees which were planted improperly, especially if planted too deep, can result in several physiological issues such as decline and dieback.
If trees reveal symptoms of premature fall color, yellowing of leaves or unusual leaf drop, it may be necessary to send in a sample for diagnosis. The Purdue Plant and Pest Diagnostic Laboratory (PPDL) provides this service by a very capable team of pathologists, entomologists and extension specialists to analyze plant issues in the landscape. This is an inexpensive approach to investigating the issues and leading to the best possible curative measures. Protocol for submitting plant samples can be found on the PPDL website.
Resources
Hardwood Tree Improvement and Regeneration Center, Paula Pijut, Research Plant Physiologist, Purdue University
Relationships Between Advance Oak Regeneration and Biotic and Abiotic Factors, Songlin Fei, Associate Professor of Measurements and Quantitative Analysis, Purdue University
Diseases of Landscape Plants: Leaf Diseases, The Education Store, Purdue Extension Resource Center
Lindsey Purcell, Urban Forestry Specialist
Department of Forestry and Natural Resources, Purdue University
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