Got Nature? Blog

Purdue Landscape Report: Mites are eight-legged arthropods who pierce plant cells to feed on them.  Plants that are attacked by mites lose their green color and appear somewhat bronzed. Spider mites will make webs to help them forage on leaves unencumbered by irregular leaf surfaces. The accumulation of webs, and old skins of mites can give heavily infested plants a dusty appearance. This can make plants unsightly and affect their health.

Lack of rain this summer and fall has spared spider mites from drowning and being washed off leaves during heavy rains.   Warm weather in late August and September allowed warm season mites, like two spotted spider mite, European red mite on flowering fruit trees, honeylocust, maple and oak spider mites to flourish. With the daily highs consistently below 85 F, cool season mites like spruce spider mite, boxwood spider mite and southern read mite have been increasing in number.

Now would be a good time to take stock of which plants have spider mites to help you plan your control strategy.

Cool season mites, including southern red mite, boxwood spider mite and spruce spider mite may require treatment this fall to keep their populations from building. This could be accomplished with a garden hose and a strong stream of water or a 2% solution of horticultural oil or insecticidal soap.

At this point in the season, there is usually no need to spray trees for warm season spider mites.  Because most spider mites will winter on trees and shrubs, these mite infested trees can be targeted for a spray of oil during the dormant season.  It is important to note that plants with two spotted spider mites will not benefit from an oil spray because they winter in the ground cover. Also, be sure not to spray oil on shrubs with waxy blue leaves. This wax often protects plant leaves from strong winds and sun in the winter.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Managing Spider Mite Mayhem with the Purdue Plant Doctor, Purdue Extension Entomology YouTube Channel
Purdue Plant Doctor Website
Spider Mites On Ornamentals, Purdue Extension Entomology Bulletin
Tree Defect Identification, The Education Store
Tree wounds and healing, Got Nature? Blog
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
Why Is My Tree Dying? – Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
The Woody Plant Seed Manual, U.S. Forest Service
Native Trees of the Midwest, The Education Store
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
Find an Arborist, International Society of Arboriculture
Subscribe Purdue Extension-Forestry and Natural Resources YouTube Channel

Cliff Sadof, Professor and Extension Fellow
Purdue Entomology

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Purdue Landscape Report: Dead man’s fingers is an apt moniker for a gruesome-looking fungus (Xylaria polymorpha and related species) that produces club-shaped fungal fruiting bodies that appear as fingers growing around the base of dying or dead woody plants and even wooden objects in soil (Fig. 1).  With more than 25 species of Xylaria, generalizations are difficult to make (Fig. 2), but we will persevere anyways, recognizing that some Xylaria species are limited to a saprophytic existence decomposing wood (like X. polymorpha) while others, like X. mali, cause an opportunistic black root rot on apple and crabapple (Rogers, 1984; Rogers and Callen, 1986) or nothing at all (Fig. 2). Other Xylaria species infect Norway maple, honey-locust, elm and pears (flowering and edible).  Perhaps the scariest thing about dead man’s fingers is its taxonomy: X. polymorpha is an extremely variable and complicated species showing “multiple interfaces and intergradations with numerous other taxa” making speciation a challenge (Lee et al, 2000), which may explain why a crabapple with a bad graft union covered in dead man’s fingers looks otherwise healthy!

Symptoms and Signs

Symptoms of infection by Xylaria may appear as stress and decline, including slowed growth, dieback, premature autumn coloration and leaf drop, and even crown or structural root cankers. Apple, crabapple or pear trees infected may produce an unusually large crop of undersized fruit.

Signs of Xylaria are more readily identified—namely, the dead man’s fingers (Fig. 4)! The club shaped, fingerlike fruiting bodies appear singularly or as clustered “fingers” about  1- 4 inches high, often at the base of infected or dying trees, or nearby large structural roots (Fig 4).  In the spring, ascospores are produced by the “fingers”, creating a bluish bloom on the tips of the fingers. Cutting into a finger reveals a white interior with black bubbles that produce the sexual spores (ascospores).  The “fingers” can release these spores for several months or years.  In the spring, Xylaria can produce asexual spores (called conidia) anywhere on its surface, while also producing threadlike structures (called hyphae) that grow through dead or dying wood.  Xylaria can survive as hyphae in roots for up to 10 years and can spread from plant to plant via hyphae when plant roots contact each other.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Tree Defect Identification, The Education Store
Tree wounds and healing, Got Nature? Blog
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
Why Is My Tree Dying? – Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
The Woody Plant Seed Manual, U.S. Forest Service
Native Trees of the Midwest, The Education Store
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
Find an Arborist, International Society of Arboriculture
Subscribe Purdue Extension-Forestry and Natural Resources YouTube Channel

Janna Beckerman, Professor of Plant Pathology
Purdue Department of Botany

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The Purdue Extension – Forestry & Natural Resources (FNR) team would like to take this time to thank our followers for their requests and comments. We received requests to improve our Purdue Extension – FNR’s Got Nature? Blog social media buttons and we would like to announce they are ready for you to share our articles. You can easily share the blog articles to X-Twitter, Facebook, LinkedIn, and Pinterest, along with an Email option.

The Got Nature? Blog was started 11 years ago to allow the FNR Extension team to share aquatic, forestry, natural resources, wildlife, urban forestry and wood products hot topics along with answering any questions regarding these areas. The blog producer Diana Evans, Web and Extension Specialist, has been with the blog from the start. The Got Nature? blog has had over 166,000 web visits in the past three years.

If you have a natural resource topic you would like to hear from our experts about, fill out our quick and easy Contact Us form.

Subscribe to our Got Nature? e-newsletter and receive our resources and updates. All email addresses are secure and only used for the Purdue Extension – Forestry and Natural Resources’ Got Nature? newsletter mailing.

What is Purdue Extension-Forestry and Natural Resources (FNR)?
Purdue Extension – FNR is a part of a larger group, the Cooperative Extension Service (CES), one of the nation’s largest and best-researched providers of science-based information and education. Purdue Extension delivers practical, research-based information and provides high-impact educational programs that enhance lives and livelihoods.

Resources:
Subscribe to Purdue Extension-FNR YouTube Channel
ID That Tree, Purdue Extension-Forestry & Natural Resources (FNR) YouTube playlist
Woodland Management Moment, Purdue Extension-FNR YouTube playlist
Ask An Expert Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Wildlife Habitat Hint Playlist, Purdue Extension – FNR YouTube Channel
Subscribe to the Purdue Extension – Forestry and Natural Resources YouTube Channel

Diana Evans, Extension & Web Communications Specialist
Purdue University Department of Forestry and Natural Resources

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This one-day workshop will focus on aquaponics in the classroom. Topics that will be covered include fish culture basics, plant culture, water quality, systems, and more. 

Workshop Participants will:

• Participate in hands-on activities.
• Learn about IISG’s NEW aquaponics curriculum.
• Tour the High School for Ag Sciences aquaponics space.
• Become eligible for a new IISG loan program.
• Hear about IISG programs.
• Be inspired to incorporate aquaponics in the classroom.

Date: Saturday, November 4, 2023
Time: 9 AM – 5 PM Central (CST)
Location: Chicago High School for Agricultural Sciences, 3857 West 111th Street, Chicago, IL, 60655

Program partners include Illinois-Indiana Sea Grant, the Center for Great Lakes Literacy, the Indiana Aquaculture Association, University of Illinois Extension, and Purdue University’s Department of Forestry and Natural Resources.

To learn more about this event and how to register please visit Purdue Extension – Forestry & Natural Resources (FNR) Events.

What is Aquaponics: Fish and Plants Grow Sustainably Through Aquaponics, IISG Newsroom

About IISG: These are trying times for the environment. Climate change and other concerns such as population growth, aquatic invasive species, contaminated waters, and loss of natural habitat, the southern Lake Michigan region faces many challenges. Illinois-Indiana Sea Grant (IISG), with its unique mandate to bring the latest science to those who can best use the information, serves a critical role in empowering people to solve problems in sustainable ways. The program is funded through National Oceanic and Atmospheric Administration (NOAA), the University of Illinois and Purdue University, but IISG also works in partnerships with key organizations, institutions, and agencies in the region to reach more audiences and multiply opportunities for success. IISG brings together scientists, educators, policy makers, community decision makers, outreach specialists, business leaders, and the general public to work towards a healthy environment and economy.

Resources:
Walleye Farmed Fish Fact Sheet, The Education Store, Purdue Extension’s resource center
Freshwater Prawn Farmed Fish Fact Sheet, The Education Store
Adaptations for Aquatic Amphibians, The Nature of Teaching, Purdue Extension – Forestry and Natural Resources (FNR)
Purdue Extension
Sustainable Aquaculture: What does it mean to you?, The Education Store
A Guide to Small-Scale Fish Processing Using Local Kitchen Facilities, The Education Store
Aquaculture Industry in Indiana Growing, Purdue Today
Purdue Aquaponics: Cut Water Usage, Purdue University YouTube Channel
Largemouth Bass Market Trends, Purdue Extension – FNR YouTube Channel

Amy Shambach, Aquaculture Marketing Outreach Associate
Purdue Department of Forestry and Natural Resources/Illinois-Indiana Sea Grant Program

Andrew Coursey, Aquaculture Specialist
Illinois-Indiana Sea Grant Program

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Purdue Landscape Report: Many areas around the Midwest continue to creep towards an increasing drought situation.  Currently almost 80% of the Midwest is listed as being abnormally dry to exceptional drought.  Current soil moisture data indicates that most of the Midwest is very dry.  Going into the fall it’s very important to supply enough supplemental water (irrigation) to make up for the deficit prior to the landscape plants going dormant over the next six to eight weeks.

The fall is a very important time to limit stressors on landscape plants.  A stressed plant doesn’t produce as many secondary metabolites which aide in increased cold hardiness; so keeping your landscape plants irrigated during dry periods in late summer into fall is an important component of preparing plants for winter.

Remember some key steps concerning your landscape during extreme dry periods:

• Don’t wait until leaves begin dropping to start watering.
• Trees should receive the 5+5 rule.
  • 5 gallons, plus 5 gallons per caliper inch.

• Ideally watering should occur in the early morning to prevent foliar diseases.
• Mulching to 3” can conserve moisture and reduce temperature in the upper root zone.
• Watering during dry conditions will help prevent future insect, disease, and other stress issues going into the fall and the following year. In fact, plants going into the winter that are stressed due to water deficiency will reduce the cold hardiness and therefore will be more likely to suffer cold injury and/or death.
• If a plant isn’t receiving enough water, the amount of nutrient uptake will not be sufficient and will experience deficiency from nutrients the following year.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Trees in Times of Drought​, Video, Purdue Agriculture
Drought Information​, Indiana Department of Natural Resources
Drought? Don’t forget the trees!, The Education Store
Safety Harvesting Quality Forage in a Drought, The Education Store
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Tree Defect Identification, The Education Store
Tree Wound and Healing, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Surface Root Syndrome, The Education Store
Planning the Tree Planting Operation, The Education Store
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
ID That Tree, Purdue Extension-FNR YouTube playlist
Subscribe – Purdue Extension-FNR YouTube Channel

Kyle Daniel, Commercial Landscape and Nursery Crops Extension Specialist
Purdue Horticulture & Landscape Architecture

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Purdue Landscape Report: Many trees are planted for their beautiful fall color, especially in locations where the climate provides reliable autumn weather. I have said this multiple times during extension talks and conversations with submitters to the Purdue Pest & Plant Diagnostic Lab (PPDL), but I seem to have not experienced a ‘normal’ fall since moving to Indiana with how erratic the weather has been from year to year. Depending on weather conditions, such as high heat and drought, colors may develop early or may be duller for specific varieties than expected.

However, individual trees that begin to show fall colors earlier than expected (August, September, even early October) may be shouting out a proverbial cry for help. Plants will often show yellow or red foliage coloration during periods of stress, so this may occur at any point during spring, summer, or fall. Individual trees may also show fall coloration earlier than others of their species in the same area.  Now is the time to keep an eye out for this kind of early fall color as it can give you a heads-up on issues you can expect next year.

When examining a tree with early fall color, I would recommend checking the following:

• Is there a root flare?
  Purdue Landscape Report: Deep Planting article
  • If not – tree could be planted too deep or the soil grade may have been changed
• Is there any obvious damage to the trunk, root flare, or surface roots?
  • If so, there could internal decay that is not obvious and could be contributing to stress
• Are there any girdling roots?
  Purdue Landscape Report: Stem Girdling Roots article
  • If present, they could be affecting the vascular system and strangling the tree
• Is the rootzone mulched?
  • If not, the tree could be under stress from earlier drought, or weed and grass competition.
  • If so, make sure it is not mounded against the trunk of the tree
• Does the soil appear compacted? Was there construction near the tree within the last 5 years?
  • Compaction leads to issues with water, nutrient, and even oxygen availability to the roots and could lead to general decline

It is important to know the host species, but with the sheer volume of plant material available for sale in the nursery trade, it is even more important to know the cultivar that you are planting so you know what you might expect coming into the fall.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Why Fall Color is Sometimes a Dud, Purdue Landscape Report
Forest Migration Plays a Role in Fall Foliage Colors, Purdue College of Agriculture News
U.S. Forest Service Fall Colors, Forest Service, U.S. Department of Agriculture
ID That Tree Fall Color: Sugar Maple, Purdue Extension – Forestry and Natural Resources YouTube Channel, ID That Tree Playlist
ID That Tree Fall Color Edition: Black Gum, Purdue Extension – FNR YouTube Channel, ID That Tree Playlist
Autumn Highlights Tour – South Campus, Purdue Arboretum Explorer
Why Leaves Change Color – the Physiological Basis, The Education Store, Purdue Extension resource center
Subscribe, Purdue Extension-Forestry and Natural Resources YouTube Channel
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Summer Tree Care, Purdue Landscape Report
Tree Defect Identification, The Education Store
Tree Wound and Healing, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Surface Root Syndrome, The Education Store
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Ask an Expert: Tree Selection and Planting, Purdue Extension-Forestry & Natural Resources (FNR) YouTube playlist
ID That Tree, Purdue Extension-FNR YouTube playlist

John Bonkowski, Plant Disease Diagnostician
Departments of Botany & Plant Pathology

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Tree-of-heaven (ToH), also known as Chinese sumac, varnish tree, or stink tree, is a large, rapidly growing deciduous tree native to parts of China. Tree-of-heaven was introduced to North America as early as the late 1700s and has since become invasive in most areas of the United States. Tree-of-heaven can be found, sometimes in abundance, in both urban and rural environments. The tree spreads through abundantly produced wind-scattered seeds from female trees, and sprout colonies arising from established trees, in some cases producing monoculture stands of the species. ToH has also been shown to produce allelopathic chemicals that can inhibit the growth of neighboring plants, providing an additional competitive advantage.

Tree-of-heaven is a serious threat as an invasive species in many habitats or untended areas. It can reach 80 feet or more, its growth rate outpaces most native tree species, and wind scatters seeds that female trees produce in abundance. Controlling ToH is a challenge. In this publication, Purdue University extension specialists and property managers explain herbicide options, application techniques and strategies to control and manage ToH.

To receive the free download visit the Purdue Extension’s resource center: The Education Store – Invasive Plant Series – Tree of Heaven, Ailanthus altissima.

View Forestry and Natural Resources (FNR) YouTube Video: ID That Tree: Invasive Tree of Heaven.

Resources:
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Invasive plants: Impact on Environment and People, The Education Store, Purdue Extension’s resource center
A Woodland Management Moment, Playlist, Purdue Extension – Forestry and Natural Resources (FNR) Youtube Channel
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR Youtube Channel
Forest Improvement Handbook, The Education Store
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
Investing in Indiana Woodlands, The Education Store
Woodland Invaders, Got Nature? Blog, Purdue Extension – FNR
Indiana Department of Natural Resources: Invasive Species
Invasive Plant Species Identification, Video, Purdue Extension – FNR Youtube Channel
Mile-a-minute Vine, The Education Store

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

Ron Rathfon, Regional Extension Forester, Southern Indiana Purdue Agriculture Center (SIPAC)
Purdue Forestry and Natural Resources

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Purdue Landscape Report: A new invasive insect of concern has been identified in the state of Georgia. In August of 2023, Georgia’s Department of Agriculture, along with the USDA, confirmed the presence of the yellow-legged hornet, Vespa velutina, outside of the city of Savannah. To date, this is the only confirmed identification of this insect in the United States; it has already established in Europe, the Middle East, and parts of Asia outside of its native range.  V. velutina is a native of the subtropical and tropical regions of southeast Asia, and it is not yet clear how it arrived in North America. Much like the northern giant hornet, previously known as the Asian giant hornet or ‘murder hornet’, this insect will attack honeybee hives in search of food and represents a potential danger to the beekeeping industry.

Yellow-legged hornets are predators and will regularly attack honeybees to provide food for their young, though it is possible they could attack other, similar species.  Since honeybees concentrate their numbers in hives with a lot of in-and-out traffic, they provide an excellent opportunity for the hornets to hunt and provide food for their young.  The hornets are effectively ambush predators, waiting in front of hive entrances and capturing workers with their legs as they leave the hive. The hornets then dismember the bees, returning to their young with only the thorax, which contains the largest amount of protein. However, it is believed that yellow-legged hornets only represent a lethal threat to weaker hives that are already experiencing problems; it is also too early to tell how already-existing honeybee issues, such as mite and disease issues, will interact with the presence of this insect.

The yellow-legged hornet, much like other members of Order Hymenoptera, is a social insect. They create oval or egg-shaped nests in trees that can house as many as 6,000 individuals. Colonies are composed of a foundress and her young, who become the workers within the colony.  Female hornets will overwinter within tree hollows, leaf litter, or other environmentally stable locations, and once spring arrives, they start their own colony and give birth to new workers who care for young and hunt.

As with any new invasive species, it is critical to successful identify it and differentiate it from other species of wasps and hornets that we experience in the Midwest.  At a glance, the yellow-legged hornet is barely discernable from European hornets, yellowjackets, and similar insects; they possess aerodynamic shapes with heavy yellow and black color patterns like many of their cousins. The most easily identified trait is their namesake: the legs of this insect tend to be black closer to the body, with the lower half of the leg bright yellow. The segments of the abdomen follow a similar pattern, with those segments closer to the center of the body being dominated by black, steadily becoming more yellow as you reach the tip of the abdomen. The yellow-legged hornet is also approximately an inch in length, with reproductive individuals sometimes reaching an inch and a half.

While remaining observant will be critical to reporting any invasive species, there are a few things to keep in mind about the yellow-legged hornet. This insect has only been found in one location in Georgia; no other states have any sightings or confirmed reports of this insect. There is also no evidence the insect has established a population in Georgia, there is only one confirmed sighting. The best course of action for now is to be vigilant and report any potential sightings by calling 1-866-NOEXOTIC, or you can contact our local Purdue Extension educator for assistance.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Pest Management, The Education Store
Protecting Pollinators: Why Should We Care About Pollinators?, The Education Store, Purdue Extension resource center
Ask The Expert: What’s Buzzing or Not Buzzing About Pollinators , Purdue Extension – Forestry & Natural Resources (FNR) YouTube Channel
Purdue Pollinator Protection publication series, Purdue Extension Entomology
Subscribe Purdue Extension-Forestry and Natural Resources YouTube Channel

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

Tom Creswell, Plant & Pest Diagnostic Laboratory Director
Purdue Botany and Plant Pathology

Cliff Sadof, Professor, Ornamental, Pest Management
Purdue Entomology Extension Coordinator

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Purdue Landscape Report: Trees stressed by prolonged drought are more subject to attack by boring insects. This article provides tips and a video link on how to manage pines for borers.

Record breaking heat and sporadic rainfall during July of 2023 took their toll on landscape trees.  Cone bearing evergreens, like white pines, are especially susceptible to drought and flooding. These environmental stresses reduce the ability of trees to defend themselves against boring insects. To make matters even worse, insect borers use their keen sense of smell to guide them to these stressed trees. Trees often take several years to recover from drought. Monitoring trees for early signs of decline is critical to a successful management program.

Early intervention can help you keep infested trees from becoming a breeding ground for borers that can destroy an entire planting.  Trees that are more than half dead, or those whose needles are mostly yellow are usually too damaged to save. Removing these trees in late fall and winter removes the reproducing borers from the landscape before borers they can emerge to attack healthy trees.  As an extra protective measure, insecticides can be applied on to the trunk to kill boring insects chewing into or out of the trees.  Apparently healthy trees located near borer-infested trees can also benefit from a soil applied insecticides, like imidacloprid or dinotefuran applied in fall and early spring.

Zimmerman pine moth (ZPM)commonly attacks pine trees in late July. Adult female moths lay eggs at the junction of tree branches and the trunk and winters in cracks and crevices. In early spring, when forsythia bloom, larvae bore inside the trunk and can girdle and kill branches and trees leaders. These are the two times of year that this borer is most susceptible to insecticides. Note soil applied imidacloprid is not particularly effective against ZPM.  Spruces and most pines are susceptible to this borer.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Borers of Pines and Other Needle Bearing Evergreens in Landscapes, The Education Store
Normal Needle Drop: Even Healthy Evergreens are not Evergreen, Purdue Landscape Report
White Pine Decline in Indiana
Tree Defect Identification, The Education Store
Tree wounds and healing, Got Nature? Blog
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
Why Is My Tree Dying? – Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Managing the Zimmerman Pine Moth, The Education Store
The Woody Plant Seed Manual, U.S. Forest Service
Native Trees of the Midwest, Purdue University Press
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store
Find an Arborist, International Society of Arboriculture
Subscribe Purdue Extension-Forestry and Natural Resources YouTube Channel

Cliff Sadof, Professor, Ornamental, Pest Management
Purdue Entomology Extension Coordinator

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Purdue Landscape Report: Despite the sublime name, tree-of-heaven, Ailanthus altissima, is a particularly bad actor when it comes to trees encountered in the Midwest. This native of Asia was introduced to North America more than 150 years ago and has since become a widespread invasive pest. Rapid growth, extremely high seed production (hundreds of thousands from a mature female tree), and root sprouting that can turn one tree into dozens makes this a formidable competitor with our native plants. Tree-of-Heaven can sprout and grow almost anywhere, including cracks in streets and sidewalks or building foundations, resulting in infrastructure damage and increased costs of maintenance. It is also the preferred host for a new and destructive invasive insect pest, the spotted lantern fly.

Reducing tree-of-heaven numbers on the landscape is a worthy goal, but can be a difficult task. Seed is windblown and can disperse for hundreds of yards or further, producing new populations. Tree-of-heaven will produce dozens of root sprouts if the stem is cut or girdled, even when herbicides are applied to the cuts. Both seedlings and root sprouts can grow rapidly, outpacing the native trees. However, there are effective control methods and even a potential biological control agent, a native wilt fungus, on the horizon. If you have tree-of-heaven or know of those who do, here are some methods to control this invasive tree.

Young seedlings and sprouts may be controlled with foliar applications of herbicides containing glyphosate during the summer growing season. Apply the herbicide and water mixture according to label directions, covering the entire leaf area. Pulling seedlings is an option, but any root fragments left in the soil may produce new sprouts.

Larger tree-of-heaven too tall for foliar spray may be controlled with a couple of other techniques. The basal bark technique applies an herbicide and oil mixture to the lower 15-18 inches of the stem of the tree. The oil carries the herbicide into the tree stem and kills the tree while also limiting the amount of root sprouting. This method is recommended for stems up to 6 inches in diameter, but larger stems have been controlled effectively with this approach. The best seasons for application are summer to winter, but avoid days where temperature is over 85 degrees F as the herbicide and oil mix can volatilize and damage non-target plants. Also discontinue applications if stems are wet or when snow cover is present. Recommended herbicides are the triclopyr ester herbicides and a commercially available basal oil mixed in a ratio of 20% herbicide and 80% oil.

Trees three or more inches in diameter may also be controlled using the “hack and squirt” method, also referred to as the injection method in some cases. A narrow cutting tool like a shingle hatchet is used to make 45 degree angled cuts through the bark of the tree around the circumference, with equal-sized uncut spaces between the cuts. Herbicides like glyphosate or triclopyr amine formulations are applied as directed on the label into the pockets created by the cuts. This treatment results in very few root sprouts as compared to cutting down or girdling the tree. The number of cuts should approximately equal the diameter of the tree in inches, and be sure to leave the uncut spaces between the cuts.

If the tree stems need to come down for safety or other reasons, apply the basal bark or hack and squirt treatments and wait approximately 30 days before cutting down the stem. This should allow time for the herbicide to impact the root system and  limit the amount of root sprouting.

Work safely for yourself and the environment by reading and following the herbicide label, wearing the required personal protective gear, and working carefully with cutting tools.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
ID That Tree: Invasive Tree of Heaven, Purdue Extension – Forestry and Natural Resource (FNR) YouTube Channel
Control & Management — State of Indiana Cooperative Invasives Management (sicim.info)
Invasive Plant Control Database (wisc.edu)
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
A Woodland Management Moment, Playlist, Purdue Extension – FNR Youtube Channel
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR Youtube Channel
Forest Improvement Handbook, The Education Store
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
Investing in Indiana Woodlands, The Education Store
Woodland Invaders, Got Nature? Blog, Purdue Extension – FNR
Indiana Department of Natural Resources: Invasive Species
Invasive Plant Species Identification, Video, Purdue Extension – FNR Youtube Channel

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

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