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Italian Arum

Arum italicum
Updated Nov 04, 2022
 
1

Make a Positive Identification

  • Plants grow about 12–18 inches tall. Leaves are shaped like an arrow with a pale green midrib and veins.
  • A perennial plant, Italium arum lives many years. It grows new leaves, flowers, and berries each year. It dies back to the ground during summer.
  • Italian arum has escaped from landscapes. It is spreading into new areas.
Species: Italian Arum
Italian arum plants with stems and leaves

Weston Miller, Oregon State University

Plants grow about 12–18 inches tall. Leaves are shaped like an arrow with a pale green midrib and veins.

Species: Italian Arum
Italian arum flower

"Arum italicum - Araceae" by Kerry  Woods is licensed under CC BY-NC-ND 2.0 (cropped).

Flowers are a yellow-cream color, and unpleasant smelling. They have a stubby spike and a large, white, funnel-shaped structure.

Species: Italian Arum
Italian arum spikes with green fruit in bare soil

Fruits are tightly clustered on spikes. They turn from green to orange-red. The fruits contain seeds that spread it to new areas.

Species: Italian Arum
Italian arum stems and tubers exposed in hole next to shovel

Weston Miller, Oregon State University

Stems extend below the soil surface. Plants form white tubers and roots. They are difficult to remove from the soil.

Species: Italian Arum
Dense patch of Italian arum

"Arum italicum" by Stepahano is licensed under CC BY-NC-SA 2.0.

It forms dense patches that are visible in fall through winter. In warm, dry summer months, the stems and leaves die back and are not visible above ground.

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LOOK-ALIKES: WAPATO AND CALLA LILY
Species: Wapato
Wapato leaves and white flowers

Wapato or broadleaf arrowhead (Sagittaria latifolia) is a native wetland plant. It has similar leaves to Italian arum. Wapato’s flowers are smaller than Italian arum flowers, as shown in the photo.

Helpful

Wapoto is an important plant in natural areas. It is used by indigenous cultures in North America. Wapato doesn’t require management.

Species: Calla Lily
Calla lily stems, leaves, and white flowers

Calla Lily (Zantedeschia aethiopica) looks similar to Italian arum. It doesn’t have white veins on the leaves. Calla lily is grown in gardens and landscapes.

Different risks or methods

Calla lily doesn’t have to be managed in the Pacific Northwest. It is invasive in coastal areas in California.

 
2

Italian Arum Benefits

  • Italian arum is an invasive weed. It doesn’t have any benefits for people and the environment.
 

Italian Arum Risks

  • Italian arum quickly grows dense stands.
  • It displaces and excludes native understory plants.
  • When Italian arum goes dormant in the summer, the stems and leaves die back.
  • It leaves the soil surface barren and susceptible to erosion.
Risk Card
Does it cause harm?
Adults & Children
High
Property
High
Pets
High
Annoyance
High
Environment
High
Action Highly Recommended
 
3

Take Action

If you have Italian arum on your property, take action to control it right away.

Do I need to take action?
Yes. Remove individual plants and small patches of Italian arum before they become a bigger problem. Both small and large patches require several years to control.

What if I do nothing?
Italian arum patches will keep spreading and become more difficult to control.

 
4

Prevent Italian Arum

Italian arum new growth
Watch for Italian Arum Each Year
  • Look for new growth of Italian arum during the winter.
  • Plan control actions in fall, winter, or early spring before seeds ripen.
  • Continue to monitor the area each year.
Italian arum ripe fruits
Remove Seeds Before They Ripen
  • At a minimum, cut and bag the fruit in August, before it scatters its seeds.
  • Dispose of the ripe fruit in a plastic bag in the trash.
Gloved hand using metal brush to clean shovel

Weston Miller, Oregon State University

Remove Dirt from Shoes & Equipment
  • Clean your boots, tools, and equipment.
  • After working or traveling in an area with Italian arum, clean your boots and tools.
  • If you drive into the ltalian arum stand, clean your vehicle.
Landscape area with native plants growing densely together

Weston Miller, Oregon State University

Install New Plants
  • Take care of the plants to get them established and to suppress Italian arum regrowth.
  • Replanting stabilizes the soil surface, shades Italian arum seedlings, and creates habitat.
  • Invasion by Italian arum and removal activities may significantly damage a site. There may be few or no desirable plants remaining.
  • Plan for at least 2-3 years of monitoring and maintenance.
  • Your local Extension specialist, soil and water conservation district, or a professional revegetation specialist can suggest strategies for your area.

 

 
5
Solutions for Italian Arum

Early Detection & Rapid Response

Watch for Italian arum on property you manage. Remove it before it becomes a bigger problem.

Physical Removal of Plants & Non-Chemical Options

  • Dig out plants. Sift the soil to remove all stems, bulbs, and roots.
  • At minimum, cut off berry clusters before they ripen and dispose of them in the trash.

Herbicides (Weed Killers)

Herbicides effectively control Italian arum when used according to the label instructions.

Monitoring & Follow-up

  • Look for Italian arum shoots in fall and winter. Look for flowers in the spring.
  • Act before or during its flowering period to keep it from spreading seeds.
  • Return to the stand. Look for regrowth throughout winter and early spring. Control Italian arum as needed each year. Seedlings are easier to kill than mature plants.
  • After you remove Italian arum, new plants will grow in the same spot unless you take steps to prevent them.

NEED HELP?

Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon  and other states  can suggest other methods.

Jump to

Method Does it work? Is it safe? Recommendation
A
Physically Remove Plants
Effective
Low risk
Recommended
B
Herbicides Glyphosate & Metsulfuron
Effective
Moderate risk
Use if Necessary
C
If Using Herbicides, Protect Yourself & Minimize Risks
 
A

Physically Remove Plants

Non-Chemical Method

Weston Miller, Oregon State University

Physically Remove Plants

Recommended
  • Dig out individual plants and sift the soil. Remove all the stems, tubers, and root pieces.
  • Dispose of the plants (all parts) in the trash. To keep Italian arum from spreading to new locations, do not compost this invasive plant.
Does it work?
Effective
  • It’s challenging to remove the tubers and root pieces from the soil. Expect Italian arum to regrow.
  • Use preventive measures for best results.
How much effort?
High effort
  • Dig out stems, tubers, and roots. Sift the soil.
  • Return to the area each year and repeat as needed.
What's the risk?
Low risk
  • All parts of this plant are toxic. It may cause skin irritation, which can be severe for sensitive individuals.
  • Digging large stands of established plants creates significant soil disturbance.
Possible risk of exposure or harm from chemicals
NONE

Dig out individual plants when the soil is moist. Plants are visible above ground from October through May. Sift the soil to remove all the stems, tubers, and root pieces.

Exposed Italian arum stems, roots, and tubers

Weston Miller, Oregon State University

Use a tool to dig around each plant. Lift and sift the soil to collect the tubers and roots. Separate the tubers and root pieces from the soil.

Sealable plastic bag next to trash can with note “invasive plant, do not compost”

Weston Miller, Oregon State University

Place the tubers and roots in a sturdy plastic bag. Label it “invasive plant, do not compost.” Place the bagged material in the trash. Or take it to a sanitary landfill for disposal. Don’t put arum remnants in a home compost pile, green waste bin, or recycling service. It could spread to new locations.

Tips for Removing Italian Arum Plants

  • Hand removal of the tubers and roots is difficult. This method is not recommended for large, established stands.
  • If you are digging in an area that floods, remove tubers completely so they don’t float downstream and take root.
  • Repeated efforts over several years may be required to remove a patch of Italian arum.
  • Dispose of the plants in the trash. Don’t put them in home compost or yard debris. Italian arum will spread to new areas.

Soil Disturbance & Erosion

  • Minimize soil disturbance as much as possible when removing Italian arum.
  • Regrade the soil after digging roots. Apply mulch (when appropriate).
  • Take steps to prevent erosion as needed.
  • Replant the area to shade out Italian arum plants.
 
B

Herbicides Glyphosate & Metsulfuron

Chemical Method: Use with caution

magesines, iStock

Herbicides Glyphosate & Metsulfuron

Use if Necessary
  • Herbicide products that contain glyphosate and metsulfuron used individually or in a mixture are somewhat effective treatments for Italian arum when used according to the label directions.
  • Metsulfuron should be used only by licensed pesticide applicators with some knowledge of how to use it.
Does it work?
Effective
  • It requires several years of effort and monitoring to get rid of Italian arum.
  • Use preventive measures for best results.
How much effort?
Moderate effort
  • Spot-spray individual plants and patches.
  • Return to the area each year and take action as needed.
What's the risk?
Moderate risk
  • Herbicides come with real risks. ALWAYS read the entire label front to back. Review instructions even for brands you know.
  • Herbicides can run off your site into waterways and may harm wildlife. See How to Keep Pesticides Out of Waterways.
Possible risk of exposure or harm from chemicals
El uso de herbicidas conlleva cierto grado de riesgo. El riesgo más bajo se presenta con el uso de métodos alternativos.

You may be exposed to an herbicide if you:

  • Get it on your skin
  • Breathe it in
  • Eat or smoke afterward without washing hands
  • Touch or eat plants that are wet with spray (you, pets, or children)
  • Bring it inside on your shoes or clothes

Follow directions closely to reduce risk.

Natural resource management professionals in New Zealand have shown that herbicide products that contain glyphosate and metsulfuron, used individually or in a mixture, are effective chemical treatments for Italian arum. Look for these chemical names in the “Active Ingredients” section of product labels.

Photo of herbicide label highlighting active ingredient glyphosate

Weston Miller, Oregon State University

  • The white box on this example product label highlights active ingredient glyphosate. Text on the label states “Kills grass and weeds around flower beds, trees, shrubs....”
  • Glyphosate will damage most plants and grasses. Don’t let the spray contact plants you want to keep.
Product lable highlighting active ingredient metsulfuron

Danny Vandecoevering, Wilbur - Ellis Company

  • Metsulfuron should be used only by licensed pesticide applicators with knowledge of how to use it.
  • Metsulfuron kills broadleaf plants and some annual grasses. It is a good choice for treating broadleaf weeds growing next to desired grasses in lawn, pasture, and meadow areas.
  • After application, the sprayer MUST NOT be used for other applications. Residue in the sprayer will destroy or badly damage broadleaf plants.

Herbicide Application Tips

  • Apply herbicides when the plants are growing. It will take several weeks for the treated plants to die. Seedlings are easier to kill than mature plants.
  • Monitor the area and repeat treatment each year, as needed.
  • Using an adjuvant (such as crop seed oil concentrates) helps the herbicides penetrate the waxy leaves.
  • Greenhouse trials show that the herbicides imazapyr, dicamba, and 2,4-D damage Italian arum.
 

If Using Herbicides, Protect Yourself & Minimize Risks

Chemical Method: Use with Caution
Blue heron in marsh

BrianLasenby, iStock

Why is it important to read herbicide labels?

  • They have detailed information on how to use the product correctly and legally.
  • They contain information on potential hazards of the product.
  • They provide instructions you should follow for poisonings and spills.
  • Following label instructions helps you to minimize the risks and maximize the benefits.

Key Herbicide Safety Tips

  • Read the entire label front to back.
  • Follow the instructions.
  • Review the instructions even for brands you know.
  • Only apply the product where the label says it may be applied.
  • Be precise in your application. More is not better.

The Label is the Law

ALWAYS read the label before using herbicide products. The label is a legal document that provides information on how to safely use the herbicide. This helps avoid harm to human health and the environment. Using an herbicide in off-label ways is illegal. It can result in legal enforcement actions.

READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.

  • Labels are different for every product and they often change over time.
  • Use a magnifying glass for small print.
  • Pay attention to CAUTION, WARNING, and DANGER statements.
  • Pay attention to the PRECAUTIONARY STATEMENTS.
  • The law states you must read and follow herbicide instructions.

Protect Yourself
Eye, skin & lung irritants

  • Wear the right protective gear. This often includes chemical-resistant gloves, safety glasses, a long-sleeve shirt, pants, socks, and shoes.
  • Mix outdoors or in a well-ventilated area.
  • Wash hands after mixing or applying, and before eating or smoking.
  • Take a shower immediately after handling herbicides.
  • Wash clothes worn while mixing or applying separately from other laundry.

Protect Children & Pets
Children and pets are at risk if they eat or touch the plants before it dries.

  • Keep them away during and after applying herbicides (read label for how long).
  • Remove toys and pet dishes from yard before applying.
  • Don’t track herbicide products into your home on shoes or clothes.

Protect Plants You Want to Keep

  • Glyphosate and similar herbicide ingredients damage both grass and broadleaf plants.
  • Minimize spraying of foliage, stems, exposed roots, or the trunks of desirable shrubs or trees to avoid harm.
  • Follow the label to avoid damaging the roots of trees and shrubs.

Don’t Spray into Water

  • It’s illegal to apply herbicides in a stream or slow moving/wetland pool.
  • You need a product registered for aquatic areas. This includes waterways, ditches, drains, and other places where water collects.

Avoid Wet, Windy, or Hot Weather
Use during favorable weather for best results.

  • Don’t spray when it’s raining or when rain is expected in the next 24 hours.
  • Wind causes spray to drift that can get on you and desired plants.
  • Herbicides may be less effective in hot weather if the target plants are moisture-stressed.
  • Some herbicides can turn into a vapor in hot weather and damage nearby plants.

Storage & Disposal

  • Store in a secure area away from children.
  • Don’t put unused herbicide products in the trash.
  • Never pour down any drain or waterway.
  • Take unused herbicides to a hazardous waste facility.

Call  1-800-CLEANUP (1-800-253-2687) to find out where to dispose of herbicides.

For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call  503-234-3000, email   or visit Metro’s website  

More about:

About Using Pesticides on School Grounds in Oregon

If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management  (Oregon Department of Agriculture).

NEED HELP?

The National Pesticide Information Center (NPIC)  can answer questions about pest control chemicals.
 1-800-858-7378 or npic@ace.orst.edu  

Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.

Your local Extension Specialist in Oregon  and other states  can suggest other methods.

Invasive Species Alert

  • Invasives are non-native species that spread aggressively and alter the environment.
  • Controlling unwanted Italian arum is costly.
  • Please do your part to control it on property you manage. Italian arum can spread beyond your property and impact your neighbors.

If you think you’ve found Italian arum in the grey areas of this map, please report it to the Oregon Invasive Species Hotline at:  1-866-INVADER (1-888-468-2337) or use their online reporting form  

open Map static invasive map
Invasive species data @ 2022, iMapInvasives (NatureServe)

If you find Italian arum in a new area (orange shows already reported cases), please report it  

View Larger Map >
SEE OTHER COMMON PACIFIC NORTHWEST WEEDS

Content provided by editor Weston Miller and writer J. Jeremiah Mann. Pesticide safety information edited by Kaci Buhl.

 Peer reviewed by OSU Department of Horticulture.

Photo of Weston Miller

Weston Miller

Project Founder and Content Writer

Weston Miller served as Community and Urban Horticulture faculty for Oregon State University Extension Service for Clackamas, Multnomah, and Washington Counties. Weston is an author for content for this website. He developed funding partnerships with Portland area agencies to initiate and build out the Solve Pest Problems website focused on this goals:

J. Jeremiah Mann

J. Jeremiah Mann

J. Jeremiah Mann completed a Physical Science undergraduate degree at Humboldt State University, and M.S, Ph.D focusing on plant science topics at UC Davis. He went on to work for the Natural Resources Conservation Service and in a leadership position serving a private agricultural technology company. He currently lives in Sacramento California where he consults on pest and property management topics.

Photo of Kaci Buhl

Kaci Buhl

At the state level, I lead the Pesticide Safety Education Program (PSEP). The program hosts live recertification events around the state, serving over 1,000 licensed pesticide applicators each year. We also produce web-based training modules and license-preparation study manuals. Special training for unlicensed pesticide applicators is also available through a grant from the USDA Specialty Crop Block Grant Program. The PSEP at OSU works closely with the Oregon Department of Agriculture's Pesticides Division.

Italian Arum References

Italian Arum  
Washington State Noxious Weed Control Board

Italian Arum (Arum italicum)  
Tualatin Soil and Water Conservation District

Italian arum  
Weedbusters New Zealand

Weed Control User Tool  
University of California ANR