OCCA’s Terrestrial Invasive Species Guide

The Asian long-horned beetle (ALB) threatens urban and suburban shade trees and recreational and forest resources valued at hundreds of billions of dollars. While the Asian long-horned beetle has largely been confined to urban and suburban parts of the state, this species could have significant impacts on our upstate forests should it spread further. The beetle could impact industries such as maple syrup production and hardwood lumber processing, nurseries and tourism.

The emerald ash borer (EAB) is an invasive beetle to eastern Asia that kills all species of ash trees in North America, and has caused severe economic and ecological damage. It was first detected near Detroit in 2002, and has now spread to 28 states, the District of Columbia, and two Canadian provinces. Ash mortality is 100% near Detroit and is widespread in all the affected areas. Since the establishment of EAB in New York State we have seen economic impacts in forests where ash is a common timber species and in urban areas where ash are frequently planted as street trees.

The hemlock woolly adelgid (HWA), is an exotic pest native to Asia and western North America.  It was first described in western North America in 1924 and first reported in the eastern United States in 1951 near Richmond, VA.  This pest is now spreading through eastern forests at an alarming rate, and has the potential to remove a major component of these forests that is important in maintaining clean water and providing valuable habitat for myriad wildlife.  This pest is now found in at least 19 states, and Otsego County stands at the crossroads of the current invasion spreading north into the Adirondacks.  It is currently found on only a handful of sites in Otsego County, but surveys and programs are being done to determine the extent of the invasion.

Spotted lanternflies (SLF) are both destructive and disruptive pests. They feed on a variety of plant species, including important crops such as grapes, apples, blueberries, hops, and forest trees like maples. Their feeding behavior can weaken host plants, making them more susceptible to secondary infections and mold growth.

In addition to being destructive, SLFs can be quite disruptive. They often occupy various surfaces and may bump into or land on people while outdoors, although they do not bite or sting. While feeding, they excrete a sugary liquid called honeydew, which drips onto whatever is below them. This sticky substance attracts ants, flies, bees, and wasps and promotes mold growth. Lanternflies are fast but somewhat clumsy when flying and hopping, which can interrupt outdoor activities.

Native to eastern Asia, the spotted lanternfly was first discovered in the United States in southeastern Pennsylvania in 2014 and has since spread rapidly. They easily hitchhike on vehicles and will lay their eggs on almost any surface from late summer through fall. If you are in an area known for spotted lanternflies, be sure to inspect your vehicle thoroughly before heading home and consider taking it to a car wash.

The Asian jumping worm (Amynthas agrestis) is an invasive species of earthworm which is native to East-Central Asia. Introduced to North America in the late-1800s, they have since spread throughout the Northeast and Midwest, spreading primarily through horticultural trade. In North America, they can be found in gardens, lawns, and wooded areas living in the leaf or mulch layer of the soil. Adult and developing jumping worms survive in wet, frost-free soil, but eggs encased in cocoons are tolerant to freezing temperatures and drought. Invasive jumping worms are smooth and glossy with a slight iridescent hue. When disturbed, they thrash wildly back and forth, and can break off tail segments to escape. They can be distinguished from other earthworms by their characteristic clitellum, which is cloudy-white to gray in color and flush with their skin. These worms outcompete other earthworms and their castings quickly degrade soil quality. Soil invaded by jumping worms has a coffee ground texture which makes it inhospitable to many native plant species and highly susceptible to erosion. Jumping worms quickly consume the top layer of organic material, making it difficult for plants to remain rooted and allowing nutrients to be washed away by rain.

Management

Preventing the introduction of Asian jumping worms is the most effective method of control. They are primarily introduced through horticulture, so it is important to avoid buying mulch, compost, nursery stocks, or potting mixes from areas with established jumping worm infestations. Once established in a garden, worms can quickly spread to surrounding natural areas. Jumping worms may also be introduced as baitworms, so anglers should avoid buying baitworms advertised as “snake worms,” “Alabama jumpers,” or “crazy worms.” If baitworms are used, it is vital to follow all proper procedures, euthanize worms before disposal, and never dispose of unused live worms into the environment.

Japanese Knotweed is not just any plant. It's a true survivor, thriving in conditions that would challenge most other plants, such as disturbed areas, roadsides, and even shaded, high-salinity, high-temperature, and drought-prone environments. This adaptability is what makes Japanese Knotweed such a formidable invader, demanding our attention for its management.

The primary objective in controlling Japanese knotweed is eliminating the rhizome system. Rhizomes are creeping underground stems that give rise to new shoots and roots. Small stands may be killed by repeated cutting, but this treatment must be repeated six times or more per season for many years. Pulling up the plants increases the risk of spreading knotweed because small pieces of root left in the soil can start a new colony. Another strategy is to smother the plants with heavy plastic or other material heavy enough to prevent the plants from growing through.

Garlic mustard, originally from Europe and Asia, was introduced to North America in the mid-1800s for its herbal and medicinal qualities.

Garlic Mustard is a biannual with a two-year life cycle; one plant can produce more than 7,000 seeds before dying. It emerges before most native plants and gains a foothold in early spring. By the time native species are ready to grow, garlic mustard has blocked their sunlight and outcompeted them for moisture and vital nutrients.

Your role in removing garlic mustard is crucial. The ultimate goal is to prevent seed development and spread. The best way to achieve this is by manually pulling the whole plant. After you have pulled the plants, bag them up and throw them out with your garbage; do not compost.

Wild parsnip resembles cultivated parsnip and belongs to the Apiaceae family. It likely escaped from gardens. The plant has yellow flowers that bloom in clusters from June to mid-July. After seeding, it dies but leaves a stalk that remains through winter. Its seeds can last in the soil for up to four years.

This invasive plant thrives in disturbed areas, especially along field and meadow edges. Once established, it spreads quickly.

While the roots are edible, the leaves, stems, and flowers contain a chemical that can cause a severe skin reaction when exposed to sunlight. This reaction, called phytophotodermatitis, can cause burning, rashes, blistering, and skin discoloration lasting up to two years. If you contact wild parsnip sap, cover the area and wash it with warm water and mild soap immediately. The skin will be sensitive for about eight hours.

To control small infestations, remove plants manually. Cut the root one inch below the ground or pull them up before they seed. If they have seeded, collect and destroy the seeds. For small areas, cut the tops and bag them in clear plastic to decompose.

Lonicera morrowii, Lonicera tatarica, and Lonicera maackii are similar-looking shrubs that grow between 6 and 15 feet tall. Lonicera japonica, however, is a woody vine that can reach 30 feet. All these species have egg-shaped leaves that grow opposite each other on hollow stems. Invasive honeysuckles flower from May to June, producing fragrant tubular flowers which can be creamy white, crimson, or various shades in between. L. morrowii and L. tatarica produce small red berries from mid-summer to early fall. L. maackii has dark red berries that ripen in late fall, while L. japonica produces dark purple or black berries in the fall.

In New York, you can find both invasive and native honeysuckles. To tell them apart, look at the stems: invasive species have hollow stems, while native species have solid stems.

These invasive honeysuckles can harm natural areas. They grow in dense thickets, leaf out early, and stay green longer than most other shrubs. This blocks sunlight, moisture, and nutrients from reaching other plants. Birds eat the fruits and spread the seeds to new locations.

If you find small plants early enough, you can pull them out by hand. In open spaces, prescribed burns can help control their growth. It's best to remove these plants before they produce berries in late summer or early fall to stop the spread of seeds.

Mile-a-minute weed (Persicaria perfoliata) is a highly invasive, fast-growing vine with sharp, barbed stems, triangular leaves, and distinctive blue fruits. Originating from India and East Asia, mile-a-minute was first reported in York County, Pennsylvania in the 1930s in contaminated nursery soil. It is estimated that mile-a-minute currently grows in about 20% of its potential U.S. range and could expand to cooler areas, as the seeds only require a two-month cold period to flower. It is named for its rapid growth (up to 6 inches/day), which allows it to smother native plants by forming dense, suffocating mats. It is considered a threat to native vegetation, nurseries, reforestation areas, young forest stands, and industries such as Christmas tree farms. Its seeds are spread via water, animals, and contaminated equipment, with seeds surviving for years, making control challenging.

Management

Management of mile-a-minute can depend on the severity of the infestation and the conditions of the specific site. Hand-pulling of vines can be effective, but caution must be exercised when removing vines with fruits. Proper disposal of the plant includes drying, burning, or bagging and bringing to a landfill. Small populations of mile-a-minute can be eliminated through repeated pulling, mowing, or cutting. There is also a biological control for this species, called the mile-a-minute weevil, a small black weevil that selectively feeds on mile-a-minute. Once the infestation has been removed, ongoing monitoring and management is necessary for up to 6 years to ensure that no seeds remain in the soil.

Pale swallow-wort (Vincetoxicum rossicum) and black swallow-wort (Vincetoxicum nigrum) are herbaceous invasive plants that were originally introduced to North American as ornamental plants. Pale and black swallow-wort are two distinct species, but have a similar growth habitat and many similar physical characteristics. Both species are perennial climbing vines that form extensive patches and overgrow and smother native vegetation. They have long, oval leaves and small, star-like flowers. Pale swallow-wort has a pink to maroon flower, while black swallow-wort has deep purple-black flowers with hairy inner petals. Black swallow-wort is native to the western Mediterranean region, and pale swallow-wort is native to Ukraine and southeastern Russia.They are typically found in upland habitats and have been observed in rocky shores, agricultural and natural fields, and woodlands. Pale and black swallow-wort are disturbance- and drought-tolerant and can quickly spread once established. A square meter stand of swallow-wort is capable of producing 1,000-2,000 seeds per year, which are then dispersed by wind. Swallow-wort may also impact monarch butterflies, which may lay their eggs on swallow-wort leaves. Monarch butterfly larvae cannot survive on swallow-wort, and monarch butterfly populations may be further impacted if swallow-wort outcompetes their preferred native larval host, common milkweed.

Management

Mechanical and manual control of swallow-wort populations is possible, but difficult due to the presence of a deep, fibrous root system. When digging up swallow-wort, ensure that you get as much of the root crown as possible. For small populations, plants and seed pods can be collected and destroyed or disposed of in a landfill before they release their seeds. Mowing can be utilized to prevent seed formation if timed correctly, when immature seed pods are just starting to develop but do not yet contain viable seeds. Mowing of swallow-wort after seed development is not recommended as it could aid in seed dispersal. Chemical herbicide treatments may be used for control, but must be conducted by a professional.

Beech Leaf Disease is caused by an invasive nematode, Litylenchus crenatae mccannii, a microscopic roundword believed to have come from Japan. The disease has become a threat to native and ornamental North American beech trees, rapidly spreading and causing severe damage, leaf deformities, and tree death. The invasive nematode feeds inside the leaf buds of beech trees. When leaves emerge, they have a characteristic striped appearance, and may become curled, leathery, or withered as the season progresses. Early in the infection, you may notice dark bands forming between leaf veins. The striping will be most apparent when looking up at leaves from below on a sunny day. Later in the infection, leaves will develop a thick, leathery texture and will start to shrivel. Over time, the canopy will thin as it loses leaves, and the tree will no longer be able to photosynthesize, causing it to die. Small saplings may die within a couple years, while larger, more mature trees can die within 7 to 10 years. The disease was only discovered in recent years and knowledge about how it spreads is limited. Unfortunately, the disease has already spread rapidly in our region. 

Management

Research into management options for beech leaf disease is in its early stages and is ongoing. Initial research and plant health care providers’ experience has shown that the use of phosphite fertilizers can help improve the natural defenses of beech trees and may inhibit nematode activity in the tree, resulting in a suppression of the disease. There are several other products licensed to treat Beech Leaf Disease in New York State, but research is still underway to understand the effectiveness of these products. If you suspect Beech Leaf Disease, document it by taking photos of affected leaves and uploading them to iMapInvasives, monitor the infestation, and avoid moving infected plant materials to prevent spread to other trees.

Giant hogweed (Heracleum mantegazzianum) is native to Eurasia, but was introduced to North America in the early 1900s as an ornamental showpiece for its massive size. It spreads easily and can establish populations along roadsides, ditches, and streams. It has a thick green stem with dark reddish-purple spots and coarse white hairs. It can grow up to 18 feet tall, with broad, deeply-lobed leaves. From late spring to mid-summer, giant hogweed produces a large upside-down umbrella-shaped head, up to 2.5 feet across, with clusters of tiny white flowers. Giant hogweed flowers once in its lifetime, with one plant producing up to 120,000 winged seeds that can remain viable in the soil for up to 15 years. The plant produces a phototoxic sap that, when exposed to sunlight, can cause severe burns on the skin. Scars may form that can last many years. Eye contact with the sap may cause temporary or permanent blindness. Giant hogweed can decrease biodiversity by shading out and outcompeting native plants through rapid growth in the early spring. When plants die back in the fall, soil is exposed, resulting in increased erosion and siltation of stream banks.

Management

The best way to manage this plant is to remove it before it produces seeds. The easiest way to remove giant hogweed is to pull it while it is still very young and small and store all plant fragments in sealed black garbage bags until the plant is dried and seeds are no longer viable. When controlling giant hogweed, make sure to wear full Personal Protective Equipment (PPE), including gloves, long sleeves, pants, a face mask, and goggles to avoid contact with its phototoxic sap. The plant should not be burned or composted.

Multiflora rose (Rosa multiflora) is native to eastern China, Japan, and Korea. It was introduced to the United States in 1866 as rootstock for grafted ornamental rose cultivars. Currently, multiflora rose is found in 41 states and is classified as either a noxious weed, prohibited invasive species, or is completely banned. Multiflora rose is in the rose family, and grows as a vigorous perennial shrub. Shrubs can grow to a height of 10-15 feet. Its red-green twigs have numerous recurved thorns. Its leaves grow alternately with saw-toothed leaflets which have short hairs on the underside. It grows clusters of fragrant white-pink flowers which bloom in May or June. Seeds can remain viable in the soil for as long as 20 years. Multiflora rose can form extremely dense thickets which exclude native plant species. This invasive rose can overrun forest edges, open woodlands, early succession pastures, and fields. It also invades fence rows, roadsides, and margins of swamps and marshes. Its impenetrable thorny thickets degrade wildlife habitats, reduce forage for livestock, and displace native flora and fauna.

Management

Mechanical and chemical methods are currently the most widespread strategies for managing infestations of multiflora rose. Seedlings can be pulled by hand, and small plants can be dug out. Larger infestations can be pulled using a chair or cable and a tractor, but care should be taken to remove all roots. Frequent, repeated cutting or mowing three to six times per growing season has been shown to be effective in achieving high mortality of multiflora rose. Cutting of individual plants is preferred to mowing in sensitive natural communities to minimize habitat disturbance. There has been some success with the use of goats to control multiflora rose.

Poison hemlock (Conium maculatum) is a highly invasive weed that is native to Europe, Asia, and Africa. It was introduced as an ornamental plant in the 1800s and is now widespread across North America. It grows in disturbed areas with high moisture, such as stream banks, ditches, riparian woodlands, and flood plains. Its seeds are dispersed by water, animal fur, birds, and human activities. Poison hemlock can be identified by its smooth, hairless, green stems with purple or reddish blotches. Its leaves are finely divided, lacy, and fern-like. The plant has small, five-petaled white flowers arranged in umbrella-shaped clusters. First year plants are low-growing, while second year plants can grow 6-10 feet tall. Poison hemlock is highly toxic when ingested. Every part of the plant is poisonous, including the seeds, roots, stems, leaves, and fruit. Symptoms of hemlock poisoning include trembling, burning of the digestive tract, dilated pupils, muscle pain or paralysis, rapid heart rate, and unconsciousness. Severe cases may result in central nervous system depression, respiratory failure, and death. It is also poisonous to animals, including pets and livestock. It is highly competitive and can displace native vegetation, resulting in reduced biodiversity. In grazing areas, poison hemlock can crowd out more desirable forage species, and its toxicity causes serious livestock losses when animals feed on fresh forage, harvested silage, or contaminated hay.

Management

Poison hemlock can be dug out in small patches, ensuring that all roots and plant fragments are removed. When dealing with poison hemlock, wear full Personal Protective Equipment (PPE), including gloves, long sleeves, pants, a face mask, and goggles. Herbicide can be used in late fall or early spring on actively growing plants, but not after flowers have bloomed. Don’t cut, mow, or burn poison hemlock. Ensure that all parts of the plant are bagged and disposed of in the trash, not composted or burned, to prevent regrowth and toxic fumes.