How to Get Rid of Italian Arum for Good

Getting rid of Italian arum permanently requires a multi-year campaign of well-timed herbicide applications, persistent manual effort, or both, because the plant regenerates from deep underground tubers that survive almost anything you throw at them in a single season. The species has a backwards growing schedule compared to most garden plants, which means the window for effective treatment is narrow and easy to miss. A three-year field study testing several herbicide combinations found that even the best treatments needed repeated annual applications to drive populations down significantly.

Why Italian Arum Is So Difficult to Kill

Italian arum operates on a schedule that feels upside down. Its leaves emerge in the fall, stay green through winter, and die back in early summer. Flowers appear in spring, and the clusters of bright orange-red berries ripen by midsummer.¹ By the time most people notice something is wrong in their yard and feel motivated to act, the plant has already retreated underground for a summer dormancy. You are essentially trying to attack an enemy that hides below ground during the months you are most active in the garden.

The real problem, though, is the tuber. Italian arum grows from a starchy underground storage organ that sits several inches deep in the soil. Even if you destroy every leaf and flower above ground, the tuber holds enough energy reserves to send up new growth the following fall. Worse, mature plants produce smaller offset tubers around the parent, each capable of becoming a new plant. A naturalized population documented in Oklahoma was establishing itself through these tuberous offsets alone, with individual plants separated by several meters despite producing no viable seed at that site.² So the plant can spread vegetatively even without its famous berries, making a single overlooked tuber fragment enough to restart an infestation.

The Best Herbicide Approach

The most rigorously tested method comes from a three-year controlled field trial that compared several herbicide treatments applied each March, when Italian arum breaks winter dormancy and begins actively growing. Researchers tested three herbicide regimes against untreated control plots: triclopyr combined with metsulfuron methyl, triclopyr alone, and glyphosate combined with metsulfuron methyl. Treatments were applied in mid-March on days when the temperature was above 10°C (50°F) and no rain was expected.³

The timing matters more than most people realize. Mid-March targets a specific vulnerability: the leaves are fully out, actively photosynthesizing, and shuttling nutrients down to the tuber. A foliar herbicide applied at this stage has the best chance of being transported into the tuber along with those nutrients. Apply too early, when growth is still sluggish, and the plant does not move enough herbicide downward. Apply too late, when the plant is already starting to go dormant for summer, and the leaves are winding down their activity. You’re aiming for that sweet spot when the plant is at peak metabolic activity above ground but hasn’t yet begun producing flowers and fruit.

Of the three herbicide combinations tested, triclopyr plus metsulfuron methyl and glyphosate plus metsulfuron methyl were both effective at reducing Italian arum cover, though repeated annual applications over three consecutive years were necessary to achieve meaningful control. This is not a one-and-done situation. If you spray once and walk away, the tubers will send up new leaves the following autumn, and you will be roughly back where you started.

Choosing Between Glyphosate and Triclopyr

For homeowners, the choice between these herbicides often comes down to what else is growing in the area. Glyphosate is a non-selective herbicide, meaning it kills virtually any green plant it touches. If your Italian arum is growing in a lawn or among desirable ground covers, glyphosate will damage or kill those plants too. Triclopyr, on the other hand, is a broadleaf-selective herbicide that generally spares grasses. If your arum is invading a lawn, triclopyr-based products are the safer bet for the surrounding turf.

The addition of metsulfuron methyl in the study’s most effective treatments is worth noting. Metsulfuron methyl is a sulfonylurea herbicide that inhibits a specific enzyme in plants, and it provides residual soil activity that can catch new shoots emerging after the initial spray. Products containing metsulfuron methyl are less commonly found on consumer shelves and are more often available through agricultural or forestry supply channels. If you can only access consumer-grade products, a concentrated triclopyr product (often sold for brush and stump killing) or a glyphosate product applied carefully is a reasonable starting point, but expect the process to take longer without the metsulfuron methyl component.

Regardless of which herbicide you choose, the application technique matters. Italian arum leaves have a waxy, somewhat glossy surface that can cause spray droplets to bead up and roll off. Adding a surfactant (a product that helps the spray stick and spread) improves absorption. Many commercial herbicide concentrates already include a surfactant, but if yours does not, a non-ionic surfactant mixed according to label directions can make a real difference.

Manual Removal and Its Limits

Plenty of gardeners prefer to avoid herbicides entirely, and Italian arum can be removed by hand, but it demands a level of thoroughness that borders on archaeological excavation. The tuber sits deep enough that a casual tug on the leaves will snap the stem without extracting the tuber. You need a digging fork or narrow trowel, and you need to go at least six to eight inches down to get beneath the main tuber and any offsets clustered around it.

Even careful digging leaves fragments behind. A small piece of tuber or a single offset the size of a pea can regenerate into a full plant. This means manual removal is less of a one-time project and more of a recurring commitment spanning several years. Each fall, when new leaves emerge, you return to the site and dig again, catching whatever you missed and whatever has grown from fragments or newly germinated seeds. Some gardeners find that combining manual removal with a targeted herbicide application on regrowth is the most effective compromise, digging out the bulk of the plants and then spot-treating survivors.

One thing manual removal has going for it is precision. In a mixed garden bed with plants you want to keep, digging gives you control that a broadcast herbicide spray cannot. You can extract individual arum plants without harming neighboring perennials. The trade-off is labor and time.

The Berry Problem

Italian arum’s bright orange-red berry clusters are not just ornamental. They are a potent dispersal mechanism. Birds eat the berries and deposit the seeds elsewhere, which is how the plant has escaped gardens and colonized natural areas across the Pacific Northwest, the Southeast, and increasingly the Midwest of the United States. A single fruiting stalk can carry dozens of berries, each containing one or more seeds.

If you are managing an existing infestation, removing the fruiting stalks before the berries ripen and turn red is one of the highest-impact things you can do. The berries typically form in late spring and ripen through June and July, depending on your climate. Cut the stalks and bag them for disposal. Do not compost them, because seeds can survive in a compost pile that does not reach sustained high temperatures. This does nothing to kill the plants already in the ground, but it prevents them from seeding new colonies elsewhere in your yard or your neighborhood.

It is also worth mentioning that every part of the plant, including the berries, contains calcium oxalate crystals and is toxic if ingested. The berries are attractive to young children because of their bright color and clustered, candy-like appearance. This is not just an aesthetic nuisance plant. Households with small children or curious pets have an additional reason to prioritize removal or at least berry-stalk removal each spring.

How Many Years You Should Expect

The controlled study that tested herbicide treatments ran for three consecutive years, with applications every March. Even after three years of treatment, the researchers noted that the study duration was not long enough to see full eradication or recovery of the treated areas.³ This is probably the most important thing to internalize before you start: plan for at least three to five years of consistent effort, and be mentally prepared for the possibility that a few stragglers will pop up even after that.

The plant’s reversed lifecycle contributes to the long timeline. Because it goes dormant underground all summer, you only get one good treatment window per year, in early to mid-spring. Miss that window, and you have lost a full year. Some people attempt a second application in late fall when the leaves first emerge, and while this can knock back foliage, the tubers are at their most energy-rich at that point, having stored reserves all summer. Fall applications tend to be less effective at killing the tuber itself compared to spring applications timed to the active-growth surge.

A reasonable multi-year plan looks something like this:

• Year one: Remove berry stalks in late spring, then apply herbicide the following March during active growth. If you prefer manual methods, dig as thoroughly as possible in late winter or early spring when the leaves make the plants easy to locate.
• Year two: Repeat the treatment on any regrowth. Expect the population to be reduced but not gone. Remove any new berry stalks.
• Year three and beyond: Continue treating survivors. By year three, you should be dealing with scattered individuals rather than dense patches, but each one needs attention.

Smothering and Other Non-Chemical Methods

Some gardeners try smothering Italian arum with landscape fabric or heavy mulch. This can suppress the plant temporarily, but the results are often disappointing. Italian arum is adapted to growing in shaded, wooded areas with leaf litter, so it already pushes through layers of organic debris as a matter of routine. A thin layer of mulch will not stop it. Heavy-duty landscape fabric pinned tightly to the ground can block light and weaken the plants over time, but the tubers can persist underground for a surprisingly long period, waiting for an opportunity. If the fabric tears, shifts, or is removed after a year or two, survivors often resprout.

Solarization, the technique of covering soil with clear plastic sheeting to heat it and kill weeds, has limited applicability here. Italian arum’s tubers are deep enough that they may not reach lethal temperatures, and the technique works best in full sun on flat ground. Since Italian arum overwhelmingly grows in partial to full shade, often under trees, solarization conditions are rarely achievable where the plant lives.

The most effective non-chemical approach remains persistent, thorough manual digging repeated over multiple years. It is labor-intensive but it works if you have the patience and do not leave tuber fragments behind.

What Happens to the Site After Removal

Killing the Italian arum is only half the battle. The study that tested herbicide treatments found that even after three years of successful suppression, almost no native vegetation had recolonized the treated plots. Before treatment, there was virtually no native vegetation present, and the study concluded that full recovery would likely depend on active replanting rather than passive natural regrowth.³

This finding has real implications for homeowners. If you clear out a dense patch of Italian arum and leave bare soil, something will fill that space, and it will probably be another weed. The areas where Italian arum thrives (moist, shady, under deciduous trees) are the same areas where English ivy, creeping buttercup, and other aggressive non-native plants tend to establish quickly. Planting native ground covers or shade-tolerant perennials into the cleared space gives desirable plants a head start over the next invader. Native sword fern, wild ginger, or other locally appropriate shade plants are good candidates depending on your region.

Replanting also serves a practical function for your Italian arum control effort. A dense, healthy ground layer of desirable plants competes with any Italian arum seedlings that germinate from the seed bank in the soil. Seeds can remain viable for several years, so even after you remove every visible plant and tuber, new seedlings may appear for a few seasons. A competitive planting makes it harder for those seedlings to establish.

How It Ends Up in Gardens in the First Place

Italian arum was sold as an ornamental plant for decades, prized for its arrow-shaped marbled leaves that appear in fall when most other perennials are dying back, and for its showy berry clusters in summer. It is still sold by some nurseries and online retailers, though several states and counties in the Pacific Northwest now classify it as a noxious weed. If you are reading this article because you inherited Italian arum from a previous homeowner or because it arrived uninvited via bird-dispersed seed, you are not alone. The plant has been moving steadily out of cultivation and into parks, forests, and riparian areas for years.

The species’ range continues to expand. A population was documented establishing itself in Oklahoma in semi-disturbed wooded habitat, spreading through tuberous offsets even without producing viable seed.² Reports like this suggest the plant is still underreported in many states and that new populations are likely being discovered as awareness grows. If you have Italian arum in your garden and neighbors who do not yet have it, preventing berry dispersal is a genuine act of neighborly goodwill, because once it gets into a wooded lot or a natural area, eradication becomes vastly more difficult and expensive than it would have been in a single garden bed.

Mistaken Identity

Before you wage a multi-year campaign against a plant, make sure it is actually Italian arum. The most common lookalike is lords-and-ladies (Arum maculatum), a related European species with a similar lifecycle but with leaves that are typically unspotted or have dark blotches rather than the pale silvery-white veining characteristic of Italian arum. In some regions, calla lily foliage or even certain hosta varieties are mistaken for Italian arum at a glance. The most reliable identification features are the combination of arrow-shaped leaves with prominent pale veins that emerge in autumn, a pale greenish-white hooded flower (spathe) in spring, and a tight cluster of green berries that ripen to bright orange-red on an upright stalk by midsummer. If you have leaves that emerge in spring and die back in fall, you are looking at a different plant entirely, because Italian arum’s reversed schedule is one of its defining traits.

Local cooperative extension offices and master gardener programs can confirm identification if you bring in a sample or a clear photograph. Getting the ID right matters because the control strategy hinges on the plant’s unusual lifecycle. Applying herbicide in midsummer to a plant you think is Italian arum will accomplish nothing if the real arum has already gone dormant underground and the foliage you are spraying belongs to something else.