Got Nature? Blog

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

---

Purdue Landscape Report: Stop me if you’ve heard this one…. A tree is in a slow decline year after year. You are called to your client’s property only to find the root flare well below grade.

Most professionals in the Green Industry have encountered this at some point in their career. The most common reason for the slow decline of trees in the landscape is due to the depth of planting and girdling roots. Deep planting can cause a number of deleterious problems, including an increase in circling/girdling roots restricting vascular tissue and decay of protective bark (Fig. 1). The vascular tissue in the bark is located on the outer portions of the trunk, while the anatomy of roots contains the vascular tissue in the center. This is why roots can graft with roots and stems can graft with stems, but also why roots can girdle the stems of trees (Fig. 2)

Excessive mounding of mulch (aka volcano mulch) (Fig. 3) can contribute to tree decline, very similar to a tree planted too deep. It’s important to remember that keeping mulch several inches away from the trunk is imperative in tree health.

If a newly transplanted tree is planted significantly too deep, a faster decline can occur, especially in plants that can’t tolerate ‘wet feet’ (aka too much soil moisture) (Fig.4). In heavy-clay soils, the negative effects on tree health increase by creating a bath-tub situation by water not draining expeditiously after a rainfall or irrigation event.

---

In this episode of ID That Tree, Purdue Extension forester Lenny Farlee introduces the Black Spruce. This species is found in bogs, wetlands, and sometimes dry sites within the North Woods of Upper Michigan and Wisconsin. Black Spruce has a bluish cast to the newest needle growth. It has single needles attached to the twigs that are typically less than an inch long. The twigs have a reddish brown cast. This tree also has small cones that are somewhat egg shaped.

If you have any questions regarding wildlife, trees, forest management, wood products, natural resource planning or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
ID That Tree, Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel (Invasive White Mulberry, Siberian Elm, Tree of Heaven)
Invasive Species Playlist, Playlist, Purdue Extension – FNR YouTube Channel (Asian Bush Honeysuckle, Burning Bush, Callery Pear, Multiflora rose)
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel (Against Invasives, Garlic Mustard, Autumn Olive)
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel (Common Buckthorn, Japanese Barberry)
Report Invasive Species, Purdue Invasive Species
The GLEDN Phone App – Great Lakes Early Detection Network
EDDMaps – Early Detection and Distribution Mapping System
How long do seeds of the invasive tree, Ailanthus altissima remain viable? (Invasive Tree of Heaven), USDA Forest Service
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Aquatic Invasive Species, Illinois-Indiana Sea Grant (IISG)
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store, Purdue Extension Resource Center
Native Trees of the Midwest, The Education Store
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store

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

---

In this episode of ID That Tree, Purdue Extension forester Lenny Farlee introduces the Quaking Aspen. This species is found in the North Woods of Northern Wisconsin, Northern Indiana, and the Upper Peninsula of Michigan. This species has simple, alternately arranged leaves. The stems are flat which allow them to quake or tremble in the wind. The stems on this species are relatively stout and have a chalky white color.

If you have any questions regarding wildlife, trees, forest management, wood products, natural resource planning or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
ID That Tree, Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel (Invasive White Mulberry, Siberian Elm, Tree of Heaven)
Quaking Aspen, Native Trees of Indiana River Walk, Purdue Fort Wayne
Invasive Species Playlist, Playlist, Purdue Extension – FNR YouTube Channel (Asian Bush Honeysuckle, Burning Bush, Callery Pear, Multiflora rose)
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel (Against Invasives, Garlic Mustard, Autumn Olive)
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel (Common Buckthorn, Japanese Barberry)
Report Invasive Species, Purdue Invasive Species
The GLEDN Phone App – Great Lakes Early Detection Network
EDDMaps – Early Detection and Distribution Mapping System
How long do seeds of the invasive tree, Ailanthus altissima remain viable? (Invasive Tree of Heaven), USDA Forest Service
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Aquatic Invasive Species, Illinois-Indiana Sea Grant (IISG)
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store, Purdue Extension Resource Center
Native Trees of the Midwest, The Education Store
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store

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

---

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

---

Starting in 2019, sassafras trees began wilting and dying in southern Indiana. It was originally thought that laurel wilt, a deadly disease in the southeastern U.S., had made its way to Indiana. However, neither the fungus responsible for causing laurel wilt nor its beetle vector were recovered from wilting trees at the time. A potentially novel fungus was recovered, as well as two invasive ambrosia beetle species. Invasive insects, particularly bark and ambrosia beetles are well-known carriers of devastating disease-causing fungi. Dutch elm disease is one of the most famous examples of a beetle-transmitted disease.

Sassafras trees are an important understory tree that aids in nutrient cycling and are important food sources for deer and rabbit populations in the winter months. They are also important to native butterfly populations like the Swallowtail butterfly, that uses sassafras as a host. At this time, we do not know what is killing our native sassafras trees or the range of impacted trees. This is a problem because if we do not know what is causing wilt or where trees are wilting, then we cannot work to identify ways to protect our native sassafras trees.

How to Identify Sassafras
Sassafras has three distinct leaf shapes. See ID That Tree: Sassafras to learn how to identify the Sassafras tree.

Wilting Sassafras
Wilting symptoms happen in late summer. Leaves turn brown, wilt and droop. Other symptoms of wilt can be canopy dieback, “noodles” from beetle activity and staining under the bark. To learn more and how you can help as scientists research what may be happening, view video: Emerging Sassafras Wilt in Indiana.

We need more help in identifying locations of wilting sassafras trees. We anticipate trees to start wilting towards the end of the summer, from late July through September. If you see any wilting or dying sassafras trees, please email sassafras.wilt@gmail.com to report it. You can also use the QR code on the bottom of the attached handout.

Resources:
Report Invasive Species, Purdue Invasive Species
ID That Tree: Sassafras
ID That Tree: Sassafras Spring Bloom Edition
Morton Arboretum: Sassafras
Sassafras, Purdue Fort Wayne Native Trees of Indiana River Walk
ID That Tree Spring Bloom Editions, Got Nature Blog
Hardwood Lumber and Veneer Series: Sassafras, The Education Store
Purdue Arboretum Explorer
The Woody Plant Seed Manual, U.S. Forest Service
Native Trees of the Midwest, The Education Store
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store
ID That Tree, Purdue Extension-Forestry & Natural Resources (FNR) YouTube playlist
Woodland Management Moment , Purdue Extension-FNR YouTube playlist

Olivia Bigham, Graduate Student
Purdue Forestry and Natural Resources & Hardwood Tree Improvement & Regeneration Center (HTIRC)

Matt Ginzel, Associate Professor
Purdue Forestry and Natural Resources & Department of Entomology

---

In this episode of ID That Tree, Purdue Extension forester Lenny Farlee introduces the Chokecherry. This species is found in the North Woods of Northern Wisconsin and the Upper Peninsula of Michigan as well as natively in Indiana in small/medium shrub form. This species has alternately held broad leaves with finely toothed margins, and has short leaf stalks. The stems are a light to medium gray color and have prominent lenticels scattered along them.

If you have any questions regarding wildlife, trees, forest management, wood products, natural resource planning or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
ID That Tree, Playlist, Purdue Extension – Forestry and Natural Resources YouTube Channel (Invasive White Mulberry, Siberian Elm, Tree of Heaven)
Invasive Species Playlist, Playlist, Purdue Extension – FNR YouTube Channel (Asian Bush Honeysuckle, Burning Bush, Callery Pear, Multiflora rose)
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel (Against Invasives, Garlic Mustard, Autumn Olive)
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel (Common Buckthorn, Japanese Barberry)
Report Invasive Species, Purdue Invasive Species
The GLEDN Phone App – Great Lakes Early Detection Network
EDDMaps – Early Detection and Distribution Mapping System
How long do seeds of the invasive tree, Ailanthus altissima remain viable? (Invasive Tree of Heaven), USDA Forest Service
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Aquatic Invasive Species, Illinois-Indiana Sea Grant (IISG)
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store, Purdue Extension Resource Center
Native Trees of the Midwest, The Education Store
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store

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

---

In this episode of ID That Tree, Purdue Extension forester Lenny Farlee introduces the White Spruce. This species is found in the North Woods of Northern Wisconsin and the Upper Peninsula of Michigan. This species has single needles attached to the twig that tend to be relatively angular and stout. The bark tends to be flaky and dark. The cones are two to three inches in length, have thin scales, and are cylindrical in shape.

If you have any questions regarding wildlife, trees, forest management, wood products, natural resource planning or other natural resource topics, feel free to contact us by using our Ask an Expert web page.

Resources:
ID That Tree, Playlist, Purdue Extension – Forestry and Natural Resources YouTube Channel (Invasive White Mulberry, Siberian Elm, Tree of Heaven)
Invasive Species Playlist, Playlist, Purdue Extension – FNR YouTube Channel (Asian Bush Honeysuckle, Burning Bush, Callery Pear, Multiflora rose)
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel (Against Invasives, Garlic Mustard, Autumn Olive)
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel (Common Buckthorn, Japanese Barberry)
Report Invasive Species, Purdue Invasive Species
The GLEDN Phone App – Great Lakes Early Detection Network
EDDMaps – Early Detection and Distribution Mapping System
How long do seeds of the invasive tree, Ailanthus altissima remain viable? (Invasive Tree of Heaven), USDA Forest Service
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Aquatic Invasive Species, Illinois-Indiana Sea Grant (IISG)
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store, Purdue Extension Resource Center
Native Trees of the Midwest, The Education Store
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store

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

---

Purdue Landscape Report: I have lost count of the number of times I’ve witnessed people working with chainsaws in shorts, a tank top, and flip flops with maybe a pair of earbuds, and it makes me cringe every time.  According to the CDC, over 36,000 chainsaw-related injuries a year are reported with annual medical costs of more than $350 million (Johnson, 2023).  Wearing the proper personal protective equipment (PPE) can help prevent accidents and injuries (Fig. 1).  PPE is there to protect you from head to toe and if you are investing in a chainsaw, it doesn’t take much more to invest in the proper PPE.  Including a work shirt and pants, if you’re using a chainsaw you should wear protection for your head, eyes and ears, hands, legs, and feet, most of which can be found at your local hardware store or home center.

Protecting your head means using a helmet, not a baseball cap or bandanna.  Depending on the type of work you’re doing there is a risk of being struck by wood or branches or if kickback occurs, sending the chainsaw back towards your head. Safety glasses will help keep sawdust and other debris out of your eyes and should be stamped with Z87.1, showing they conform to ANSI safety regulations.  Normal glasses and sunglasses are not rated for being struck and can shatter, sending broken lenses into your eyes.  Ear protection can be in the form of plugs or muffs and should be rated to reduce noise to appropriate levels when worn properly.

Most modern chainsaws have built-in anti vibration technology to reduce fatigue, but having a nice pair of work gloves will still help to protect your hands and grip.  Gloves will help protect against debris and are also good to wear for chainsaw maintenance.  Although not about PPE, another note on protecting your hands when operating a chainsaw includes the proper use of the chain brake.  Injuries can occur on the right hand because operators will remove it from the back handle to activate the chain brake with the palm of their hand and miss it, putting their hand on the still moving chain.  Injuries on either hand can happen when one handing a saw while using your other hand to brace or manage what you are cutting and losing control.  The chain brake is designed to be engaged by popping your left wrist forward while maintaining a grip with both hands on the handles.

To protect your legs some form of chaps or chap pants are needed.  Prices can range from around $40 for a pair of wrap-chaps that can be worn over your work pants up to around $400 for a high-end pair of chap pants that are a stand-alone work pant replacement.  Whichever you choose to wear, the protection should be from the top of your thigh to the top of your foot and wrap around your calf.  Care should be taken to keep them clean from gas and oil and if they are ever damaged by a chainsaw, chaps should be discarded and replaced.  Once the protective material has been damaged the safety has been compromised.  Chainsaw boots are also available to protect your lower legs and feet but are expensive and can be heavy.  A sturdy work boot should be worn at the very least while staying alert to how close the chainsaw is coming to you.  And please, no open-toed shoes.

Whatever the task, if you are going to do your own chainsaw work, then I implore you to wear your PPE from head to toe.  I know it’s hot and can get uncomfortable, but all it takes is one mistake to send you to the ER.  If you feel the job is beyond your capabilities you can always contact an ISA certified arborist at Find an Arborist through the treesaregood.org website.

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:
The Purdue Landscape Report
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
Find an Arborist website, Trees are Good, International Society of Arboriculture (ISA)
Caring for storm-damaged trees/How to Acidify Soil in the Yard – In the Grow, Purdue Extension
Moist soil and rotten roots makes it easy for trees to come crashing down – Fox 59 News
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
Mechanical Damage to Trees: Mowing and Maintenance Equipment – The Education Store
Trees and Electric Lines – The Education Store
Tree Support Systems, The Education Store
Corrective Pruning for Deciduous Trees, The Education Store
Tree Installation: Process and Practices, The Education Store

Ben McCallister, Urban Forestry Specialist
Purdue Forestry & Natural Resources

---

Purdue Landscape Report: Poison hemlock was introduced to North America as a garden/ornamental plant. It is a native of Europe, and it is a member of the Apiaceae (parsley) family.

Purdue experts Bill Johnson and Marcelo Zimmer wrote about poison hemlock in a Purdue Pest & Crop newsletter.

They wrote that poison hemlock can be noticed very early in the spring every year, as it is typically one of the first weeds to green up, usually in late February to early March if temperatures are favorable. They said the largest threat of this weed is the toxicity of its alkaloids if ingested by livestock or humans, but it can also reduce the aesthetic value of landscapes and has been reported to creep into no-till corn and soybean fields as well.

Purdue Extension’s fact sheet on poison hemlock states that it can also be found along roads, streams, trails, ditches, forest edges, and waste areas.

The Purdue experts said that poison hemlock is a biennial weed that exists as a low-growing herb in the first year, and bolts to three to eight feet tall in the second year, when it produces flowers and seed. It is often not noticed until the bolting and reproductive stages of the second year. Poison hemlock is often confused with wild carrot, but can be distinguished by its lack of hairs and purple blotches that occur on the stems.

The experts pointed out that poison hemlock contains five alkaloids that are toxic to humans and livestock, and it can be lethal if ingested. They warn that the plant’s alkaloids may also be absorbed through the skin, so if you find yourself hand-pulling poison hemlock, it would be a good idea to wear gloves. All parts of the plants contain the toxic alkaloids with levels being variable throughout the year. Symptoms of toxicity include nervousness, trembling, and loss of coordination followed by depression, coma, and/or death. Initial symptoms will occur within a few hours of ingestion.

For history buffs, the Greek philosopher Socrates was sentenced to death by hemlock poisoning.

Cases of poisoning due to poison hemlock ingestion are rare as the plants emit a mousy odor that makes it undesirable and unpalatable to livestock and humans. Consumption and toxicity in animals usually occur in poorly managed or overgrazed pastures where animals are forced to graze poison hemlock because desirable forage is lacking.

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:
Recognizing and Managing Poison Hemlock, Purdue Landscape Report
Purdue Pest & Crop Newsletter
Invasive Plant Species Fact Sheets: Poison Hemlock, The Education Store, Purdue Extension Resource Center
Hemlock Woolly Adelgid: Distribution Update, Purdue Landscape Report
Be Careful Around Highly Toxic Poison Hemlock Plant This Summer, Purdue Extension – Forestry and Natural Resources (FNR)
Poison Hemlock (Conium maculatum), United States Department of Agriculture (USDA)
Invasive plants: impact on environment and people, The Education Store, Purdue Extension’s resource center
Woodland Management Moment: Invasive Species Control Process, Video, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Report Invasive, Purdue College of Agriculture – Entomology
Purdue Pest and Plant Diagnostic Lab, send in photo or sample

John Woodmansee, Extension Educator, Whitely County
Purdue Extension

---