Mouse barley (Hordeum murinum ssp. leporinum), also known as wall barley or hare barley, is an invasive grass that is new to the Eastern United States. The ripe seeds of mouse barley catch on to the fur of passing animals, and then, as the awns and barbs wear down over time, drop off at a distant location. However, seeds caught near the face, paws, armpits, groin, rear end, and other areas, can gradually work their way inside an animal, causing pain, and dysfunction. Dogs, cats, and horses are all documented victims of mouse barley. Presumably several species of wildlife are similarly affected. For its harm to animals, and to the people that love them, mouse barley has been chosen as this MISC Invader of the Month.

Photo caption: As summer begins, mouse barley spikes (above) turn tan. When a ripe seed breaks off from the tip of the spike, it takes the surrounding awns and a little bit of the stem with it. When the resulting dispersal unit attaches to a passing animal, or to clothes, it can be carried to distant locations. The remainder of the spike has a broken-off look that can be seen from a few feet away and, in our region, is unique to the three barley species discussed in this article. June 22, 2023. Truxton Circle, Washington, D.C.

Photo caption: Mouse barley dispersal units have an intricate system of backward-pointing barbs. Once the unit is caught up in an animal’s fur, the sharp tip can easily penetrate skin or other membranes. The common orientation of the barbs allows the unit to burrow into an animal but prevents it from being pushed outward (Brenner, 1983). The dispersal unit shown is about 1.5 inches long (3.5cm).

Physical description –

Mouse barley is a winter annual that can reach a height of 44 inches. Mowed plants tend to be shorter and somewhat prostrate. Like other members of the wheat family, it produces characteristic inflorescences called ears or spikes. Grasses can be challenging to identify, and, in our region, this one has two look-alikes. These tips will help you to tell them apart.

1. Foxtail barley (H. jubatum) is also a short, introduced plant that frequents roadside habitats. You can easily recognize foxtail barley by its luxuriously long awns, lax spikes, and plain, green auricles that lack protrusions.
2. Little barley (H. pusillum) is another short barley often found in disturbed habitats, however it is native. You can easily tell little barley by its narrow spikes, shorter awns, and plain, green auricles that lack protrusions.

Caption for 3-photo set: In late spring, barley plants begin to flower. The flowerheads, known as “ears” or “spikes”, can be used to tell the species apart. The spikes of foxtail, mouse, and little barley (L to R) have long, medium, and short awns, respectively. The spikes of foxtail barley (L) are somewhat lax, whereas the spikes of mouse and little barley are erect. These are photos of young, green plants. As the spikes mature, they turn tan and the awns spread out more. Credits (L to R): Matt Lavin via iNaturalist CC BY, July 22, 2009, Bozeman MT; same, May 18, 2009, Unionville NV; Eric Hough via iNaturalist CC BY NC, May 7, 2024, Rio Verde AZ.

Caption: Where the leaf blade meets the sheath, mouse barley has a white band with protrusions called auricles. Sometimes mouse barley auricles are so long that they cross over each other, as shown here. Little barley and foxtail barley lack auricles. This difference is helpful for ID even before the grasses begin to flower. June 6, 2023. Ogden Street NW, Washington, D.C.

Habitat and distribution –

Mouse barley is native to the eastern Mediterranean region, where it is found in disturbed areas, but can also show up in meadows, pastures, and farm fields. It may have arrived in California with the Spanish settlers (Cal IPC). More locally, iNaturalist records show that it was in the District of Columbia by 2017, and in Maryland by 2020, where it is found almost exclusively in hell strips and median strips. These areas may resemble the warm, wet winters and the hot dry summers of their homeland. It is too early to tell the full range of habitats that will be invaded in our region, but we do have natural meadow communities that are characterized by hot, dry soils in summer.

Caption: An entire hell strip infested with mouse barley. People and animals getting in and out of cars, or dogs being taken for a walk here, are likely to become seed dispersal vectors. Ogden St. NW, Washington, D.C. June 8, 2024.

Call to Action –

We can’t know for certain how mouse barley arrived in Washington D.C., but its appearance in hell strips hints at the possibility that someone visiting the Central or Western U.S. may have inadvertently brought it back on their shoes, socks, or even on their dog. Now that it is here, it is spreading rapidly.

We may still have a window of opportunity to eradicate this species from the Eastern U.S. At the time of this writing, iNaturalist research-grade observations suggest only small infestations in New York City and Washington, D.C. (there are no Eastern U.S. reports in EDDMapS). Please help by reporting mouse barley when you see it. This link will show you current research-grade mouse barley iNaturalist observations for Maryland and the District of Columbia.

You can also help by sharing this information with friends that own cats, dogs, or horses, and your veterinarian, and anyone you know who manages the vegetation along roads and sidewalks.

Prevention/Management –

To prevent further spread, keep pets and people out of infested areas. Small patches can be pulled. Pull plants before the seed is ripe to prevent inadvertent spread. In our area, this probably means pulling the plants after the spikes appear in April – May, because that’s when we will become alert to their presence, but before the seeds begin to ripen in late May – June. Mowing has not been shown to be an effective control method and could result in spreading the seed to new locations.

The species is effectively managed by hand pulling and glyphosate. The existing literature on chemical management focuses on pasture infestations and the findings to date don’t show a clear path forward. Research is needed on management of mouse barley in roadside settings. Whatever management approach is implemented, it must be repeated until the plants stop returning. The literature suggests that this may occur within two or three years.

If you have mouse barley on private property and need herbicide advice, please contact Extension’s Ask-An-Expert service https://ask2.extension.org/open.php. We do not encourage individuals to apply herbicides to public land, and hand pulling plants near roads could be dangerous.

Photo credits: Photos by Sara Tangren, CC-BY-NC, unless otherwise noted. Most are available for download here: https://www.inaturalist.org/observations/166412584.

References (Caution: Some publications contain photographs of wounded or dead pets.)

Angel-Caraza, J., et al. 2011. Case Report: Mouse barley awn (Hordeum murinum) migration induced cystolithiasis in 2 male dogs. Can Vet J 52:67–69 https://www.researchgate.net/publication/50990084_Mouse_barley_awn_Hordeum_murinum_migration_induced _cystolithiasis_in_2_male_dogs Cal IPC. (n.d.) Hordeum murinum. https://www.cal-ipc.org/plants/profile/horderum-murinum-profile/

Combs, M., et al. 2017. Grass seed foreign body-related disease in dogs and cats: a wide spectrum of clinical presentations. Australian Veterinary Practitioner 47(1):13-24. https://www.researchgate.net/profile/Martin-Combs/publication/316472971_Grass_seed_foreign_bodyrelated_disease_in_dogs_and_cats_A_wide_spectrum_of_clinical_presentations/links/5c985f81a6fdccd46038526b /Grass-seed-foreign-body-related-disease-in-dogs-and-cats-A-wide-spectrum-of-clinical-presentations.pdf

Mohammadi, G and K. Sardari. 2009. Ulcerative stomatitis due to Hordeum murinum: An outbreak of ulcerative stomatitis due to mouse barely (Hordeum murinum) in horse. Iranian Journal of Veterinary Science and Technology 1(1):47-52. https://ijvst.um.ac.ir/article_25242_5ab574a326c5445c16d787a1e5ce2ea6.pdf

von Bothmer, R., C. Badenf, and N. Jacobsen. Hordeum L. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico [Online]. 25+ vols. New York and Oxford. Vol. 24. http://floranorthamerica.org/Hordeum. Accessed Jun 20, 2024.

Weakley, A.S., and Southeastern Flora Team. 2024. Flora of the Southeastern United States Web App. University of North Carolina Herbarium, North Carolina Botanical Garden, Chapel Hill, U.S.A. fsus.ncbg.unc.edu. Accessed Jun 20, 2024.

The post Fur real, this pest can kill animals! first appeared on Maryland Invasive Species Council.

Palmer amaranth was first discovered in Maryland during the mid-twentieth century, but wasn’t added to the Maryland Noxious Weed Law until 2020. This law prohibits the import and transport of the noxious weed throughout the state and requires infested lands be managed for the eradication of the species. Palmer amaranth is problematic for landowners and farm tenants because of its dominance once established and the difficulty to fully eradicate it. For this reason, Palmer amaranth has been chosen as MISC’s Invader of the Month for October 2023.

Physical Description

Palmer amaranth has three growing stages. The first stage is the cotyledon ‘seedling’ stage when the plant will start to emerge in late April to early May with a similar look to other pigweeds. Palmer amaranth leaves are diamond-shaped, lack hairs on surface, and sometimes contain a white or purple watermark. Leaf petioles of older leaves are as long or longer than the leaf blades and stems are smooth and hairless. Other pigweed species leaves have a similar appearance, but have hair on the stems and the petiole length to leaf blade length ratio is not as dramatic. The second stage is the intermediate growth stage where a female and male plant are present. Palmer amaranth is dioecious, having separate male and female plants. The female Palmer amaranth plant will start growing stiff bracts at the leaf axil that have a prickly feel to it, while the male Palmer amaranth plant will have a softer feel with no prickly bracts. The third and final stage is the reproductive adult stage where the female Palmer amaranth will produce 250,000—600,000 seeds per plant, and flower heads will harden, becoming pricklier. Male Palmer amaranth plants will produce pollen.

Habitat & Distribution

Native to the Sonora Desert of Arizona and Northern Mexico, Palmer amaranth is well adapted to the hot Maryland summers. It is mostly found in agricultural crops such as corn, soybeans, lima beans, and other vegetable fields or anywhere the land has been disturbed and seed can make bare ground contact. It’s most problematic in organic systems where the farmer is limited in the methods used to control it. It has recently been found along roadway routes where commodity crops travel to grain elevators and mills, in guardrails and right of ways. Although it’s been identified in each region of Maryland, it’s most prevalent on Maryland’s Eastern Shore.

Background

Palmer amaranth is a summer annual weed in the pigweed family that has become a major challenge for the farmers across the U.S. for much of the decade. It is one of the most troublesome weeds in the United States due to the economic and ecologic harm it causes to our private and public lands, specifically in the agronomic crop production systems. Studies have shown 79% – 91% yield loss in corn and soybean crops once Palmer amaranth is established. Female plants can produce upwards of 600,000 seeds per plant and their rapid growth of 2-4 inches per day make them difficult to control in a timely manner. Once plants get to be larger than 4” in height, control methods are more difficult and expensive. This adds an additional cost to farmers and land managers and limits landowners who may not have herbicide knowledge to properly control the weed.

Prevention/Management

Control practices include treatment with an approved herbicide, cultivation or hand pulling. However, Palmer amaranth has shown resistance to multiple herbicides which limits its use. In organic systems, weed electrocution (Weed Zapper) or flaming (the use of fire) in between the rows may be used to control Palmer amaranth. The best way to prevent the spread of Palmer amaranth is to scout the land early in the growing season, identify new infestations quickly and initiate steps to prevent its establishment and spread. Additionally, prevent seeds from entering the farm by cleaning equipment thoroughly.

The Maryland Department of Agriculture has entered into an agreement with 16 Counties throughout the State to provide technical assistance to landowners for initiating noxious weed control programs. Many of the programs provide herbicide applicate to landowners on a fee for service basis. To learn more, please contact your area’s weed control program. For assistance with weed identification, contact your local Extension office.

The post Palmer Amaranth: The Most Obnoxious Noxious Weed in Maryland first appeared on Maryland Invasive Species Council.

One of the most popular flowering trees in Maryland is the Crapemyrtle (Lagerstroemia indica). Producing an abundance of showy flowers in late summer and early fall, it brings a splash of color when most trees and shrubs are going dormant. It also has a pleasing, smooth bark, which reveals multiple colors as it peels. It is one of the nursery industries biggest sellers and because of its general lack of diseases and insect pests in our area is an easy plant to maintain in the landscape. That has changed dramatically with the detection of Crapemyrtle bark scale (Acanthococcus lagerstroemiae), a scale insect that covers the bark of crapemyrtles, and feeds on the sap of the tree. This pest has also been detected on other plants, including beauty berry, a Maryland native, and soybeans. Because of the potential spread to native plants and serious damage to a popular landscape plant, the Crapemyrtle bark scale has been selected as this month’s Maryland Invasives Species Council Invader of the Month.

Crapemyrtle bark scale was first detected in the United States in central Texas in 2004. It has since spread East and north to Virginia and Delaware. It has now been documented in Maryland. 

Crapemyrtle bark scale is a bark or felt scale, slightly different than a soft scale insect, but like soft scales produce a waxy coating to protect the larvae, adults and their eggs. These are small insects, no more than 2 millimeters in length. Females do not move once they attach to the twig or branch. Males are winged and fly to the females to mate. Once the females produce an ovisac, or egg case, they die, leaving the eggs protected under the waxy coating. When they hatch, the nymphs or ‘crawlers’ will move to a fresh site on the twig and start the cycle over again. As with most scale insects, they are most vulnerable in the crawler stage. They can attach anywhere there is room on the twig or branch and will concentrate around pruning cuts. There are 2 to 4 generations in a year, reproducing rapidly. The number of generations in Maryland and Delaware have not been documented, however, researchers Dr.’s Stanton Gill of University of Maryland Extension, and Brian Kunkel, of University of Delaware have a study in progress to determine this. Crapemyrtle bark scale also produces copious amounts of “honey dew,” a secretion which attracts insects feeding on the sugars in the extract, and also provides a medium for sooty mold, that stains the foliage and bark, leaving an unsightly appearance. Crapemyrtle bark scale can be fatal in extreme situations. In most instances however, the effect is a combination of a degraded visual appearance, and the weakening of the tree.

Crapemyrtle bark scale is not just found on its namesake. It has been found on American beautyberry, a popular shrub often used in landscape and restoration plantings. Potentially, there are up to 30 different plants that could be a host for this insect, including persimmon and soybeans. The impacts on crapemyrtle alone is enough to cause concern as it is one of the most popular choices as a flowering small tree in landscapes in Maryland. Crapemyrtle is popular not only for its flowering ability but also for its general lack of insect pests, with crapemyrtle aphids being the other pest that causes problems. This insect pest will increase the need for maintenance, including pesticide use.

Crapemyrtle itself is a nonnative invasive species with documentation in most of the southeastern states including Maryland. Fortunately, it is not as aggressive as other invasive tree species. The best way to avoid Crapemyrtle bark scale is not to plant crapemyrtles. There are native alternatives such as service berry Amelanchier arborea, flowering dogwood Cornus florida, redbud Cercis canadensis, and witch hazel, Hamamelis virginiana L. that have showy flowers as well. If you already have crapemyrtles, check for infestations and if severe, contact a certified arborist. Control in light infestations may just require spraying a with a garden hose to wash them off the branches and twigs. This can also alleviate the sooty mold that grows on the honeydew that they produce in abundant amounts.

 Severe cases may require the use of pesticides. Horticultural oil and insecticidal soaps are often used on scale insects. Insecticides such as the neonicotinoids can also be used on soft scales but must be applied by professionals. Because of the risk of harming pollinators when using neonicotinoids, growth regulating pesticides such as pyriproxyfen (trade name -Distance) and Buprofezin (trade name – Talus), which interfere with the development of the larvae and \or eggs to maturity, are recommended from an Integrated Pest Management position. Pesticides must be used according to the label, and while wearing personal protection equipment to protect the applicator. If help is needed, contact your agricultural extension agent or a licensed commercial applicator.

It is believed that this invasive pest will spread rapidly throughout Maryland in the coming years.  Careful monitoring and measures taken to control it will lessen the impact it will have on one of the most popular ornamental trees in Maryland.

https://extension.umd.edu/resource/crapemyrtle-bark-scale-new-problem-home-landscapes

The post Watch out for Creepers on your Crapemyrtle! first appeared on Maryland Invasive Species Council.

It’s been more than four years since spotted lanternfly (Lycorma delicatula) made its way into the Maryland Invasive Species Council’s Invader of the Month. While some folks may have lost track of it, this pernicious insect has unfortunately been very busy. From its original discovery in Cecil County in 2018, spotted lanternfly has become established in sixteen counties. Along with its invasion, spotted lanternfly has brought along a raft of problems including loss of vineyard crops, unbearably dense swarms, thick mats of sooty mold, and visiting stinging insects interested in feasting on lanternfly honeydew. Spotted lanternfly continues to be a problem for Marylanders, and there does not appear to be an end in sight. For this reason, spotted lanternfly has been chosen as MISC’s Invader of the Month for January 2023.

The spotted lanternfly is an east Asian insect that originates in southern China. In the United States it was first discovered in 2014 in Berks County, PA, though it is thought that the insect may have established sometime before 2014. From there it spread, coming to inhabit the entire Mid-Atlantic region. In Maryland, lanternfly was first found in 2018, in Cecil County. As of 2022 the lanternfly has become established across most Maryland counties.

Spotted lanternfly has six life stages. The first three nymphal instars are similar looking, only distinguishable by their increasing size. They are jet black with a smattering of white dots all over their bodies. These first appear in early May and continue to molt until they reach the 4^th instar in June. Fourth instars are large with vivid red and white markings. Adults molt in July and persist until the first hard freeze of the year, usually sometime in mid-November. They are characterized by their spotted forewings and bright red hindwings, which are visible in flight. Egg masses are laid beginning in October and overwinter until they hatch the following May. Egg masses appear nothing so much as a patch of gray mud on plants and manmade structures.

Spotted lanternfly is a consummate invader. It readily invades crop fields, dense woodlands, city centers, and suburban communities. It feeds on a wide variety of plants in North America, 82 and counting! This makes it extremely difficult, if not impossible, to suppress. It is most frequently found on trees. Tree of heaven (Ailanthus altissima) is its preferred host. But it has a number of other hosts that it is fond of, including grape, black walnut, red and silver maples, eastern white pine, and willows. Keep an eye on these trees when monitoring your local spotted lanternfly. Lanternfly is a frequent hitchhiker and is frequently spread via trucks, cars, trains, and ships. Rail is a particularly potent vector of spotted lanternfly.

The danger posed by spotted lanternfly comes in two forms. The first is as an agricultural pest. Lanternfly is strongly attracted to grape vines. This means that the state’s vineyards have been placed under enormous pressure by swarms of thousands of hungry lanternfly. Feeding by these insects robs the vines of vital carbohydrates that they would otherwise sequester for winter. The honeydew that lanternfly produces also encourages the growth of naturally occurring sooty mold. This mold can grow over photosynthesizing greenery, reducing its photosynthetic potential or even killing it. This is important because Maryland’s wineries contribute roughly $3.16 billion to the state’s economy and employ 22,455 workers as of 2022 (wineamerica.org). Lanternfly can also infest nurseries and orchards, where the insects pose a risk by spreading sooty mold, harassing workers and visitors, and contaminating shippable products. Maryland’s horticultural industry, of which nurseries and orchards are a part, constituted 9% of the state’s economy in 2017. In 2018, the horticultural sector totaled $1.9 billion in sales, and employed roughly 25,000 workers (https://msa.maryland.gov/msa/mdmanual).  

The second danger posed by spotted lanternfly is as a public nuisance. This is particularly significant for communities located in the most heavily infested areas. Residents of places like Hagerstown, Havre de Grace, and Perryville must all contend with massive swarms of lanternfly on their properties. The insects plaster the sides of homes, divebomb people trying to enjoy the outdoors, feed on gardens and ornamentals, spread sooty mold over vehicles and buildings, and attract stinging insects that feed on the lanternfly’s honeydew.

            The Department of Agriculture, in cooperation with other state and federal agencies, has devised a few measures to help slow the spread of spotted lanternfly. First, a quarantine order has been put into effect for counties with reproducing populations of lanternfly. This quarantine has several knock-on effects. It requires that a business that moves regulated articles from or within the quarantined area acquire a permit. Permit training can be found at https://extension.psu.edu/slf-permit-training-md. It is only necessary for a single representative to take the training. Once complete, that representative is expected to train other employees on the identification and management of spotted lanternfly. Maryland residents can take the training, however it is not required by law.

The second measure is to destroy spotted lanternfly wherever it is found. This can involve physically smashing or trapping the insects. I have often been told that tennis rackets and fly swatters work well. Catching nymphs and adults in liquids such as ethyl-alcohol or a 50/50 mix of liquid dish soap and water, can be effective. Traps are effective at catching nymphs and adults. Adhesive traps can be purchased or crafted and placed on infested trees. Be wary that while adhesive strips seem low maintenance, anything can get stuck to them. Check your adhesive traps for stuck birds, mammals, and reptiles. Bag traps can be purchased or crafted and have the benefit of not trapping non-target animals. During the winter, egg masses are the name of the game. They can be located on trees and structures where lanternfly adults congregate. Egg masses should be crushed by pressing directly down on them. They can be scraped, however; they should then be deposited in a container full of alcohol, vinegar, or diluted dish soap. Egg masses that are scraped can potentially survive to hatch in the spring.

Insecticides can also be applied. Residents should be judicious when using insecticides. Consult University of Maryland Extension to determine the most appropriate insecticide to use. Such questions can be directed to https://extension.umd.edu/ask-extension. The Department of Agriculture is a pesticide regulator and cannot make recommendations as to what insecticides should be used against spotted lanternfly.

 The Department of Agriculture asks that Marylanders report lanternfly sightings to our online survey at mda.maryland.gov/spottedlanternfly. It is especially important that residents keep their vehicles as sanitary as possible. Lanternfly is a notorious hitchhiker. Try your best to remove all lanternfly life stages from your vehicle before you travel. The state does employ a small treatment program that targets high-risk properties associated with new infestations, and transportation and agriculture businesses, however; we are not able to treat most residential properties. Residents will need to pursue management options on their own initiative. Together we can all work to slow the spread of spotted lanternfly!

• For more information visit our website at mda.maryland.gov/spottedlanternfly.
• For tips on management and identification visit UMD Extension at https://extension.umd.edu/resource/spotted-lanternfly-management-residents.
  
  

The post We are legion, we are lanternfly first appeared on Maryland Invasive Species Council.

Natasha Shangold, City of Rockville nshangold@rockvillemd.gov

As we are in the midst of summer, many of us enjoy planting a garden full of fresh veggies and herbs for ourselves and perhaps pollinators, or some of us may even enjoy foraging around. To those who are familiar with the Apiaceae family, these plants contain carrots, parsley, dill, and many others but not all are edible. Enter Conium maculatum, also known as Poison Hemlock and commonly named this for good reason, is also part of the Apiaceae family, a biennial growing 6 to 10 feet in height with small white flowers in clusters along ditches, bordering pastures and croplands, and roadsides with a bad musty odor.

Originally from the Mediterranean region and native throughout northern Europe, western Asia, and northern Africa, it was thought to be the poison used against the Greek philosopher Socrates as it contains high concentrations of the chemical coniine, which paralyses the motor nerve endings of the skeletal muscles and depresses the autonomous nervous system, causing the toxic effects (Alliance for the Chesapeake Bay, 2019). Symptoms of poisoning include salivation, vision impairment, stomach pain, seizures, paralysis, coma, and if consumed at a high dosage, death (Alliance for the Chesapeake Bay, 2019). While it may appear similar to Queen Anne’s Lace, Poison Hemlock will have a smooth stem with purple splotches and lacy pale green leaves (Nibalia, 2018).

As Maryland continues to disturb land areas for new developments, Poison Hemlock will be able to thrive in these areas, especially those with adequate moisture and low elevations. Roadsides are the most problematic because as mowers cut the plant, they can spread the seeds even further around at far distances (Fitch, 2018). Additionally, as it can be poisonous to humans and livestock, it is best to remove as quickly as possible when detected.

When removing Poison Hemlock, whether by hand or mowing (though mowing is not recommended as mentioned before because it can spread plant material around) or applying herbicide, wear gloves, long pants, long sleeves, and a face mask. Also, once removal is complete, immediately take a shower as well as wash clothes separately from other laundry (Nibalia, 2018).

While we may have purple carrots, we should be skeptical when we see purple stems above ground. All in all, stick with what you know and love to plant but remember to continue to plant native Apiaceae plants to help our pollinators and provide a host plant to the Black Swallowtail butterfly.

References

Alliance for the Chesapeake Bay. (2019, August 8). Dangerous plants of the Chesapeake Bay watershed. https://www.allianceforthebay.org/2019/08/dangerous-plants/

Fitch, J. (2018, June 24). Poison hemlock spotted in area pastures, roadsides in Tri-State area. Herald Mail Media. https://www.heraldmailmedia.com/story/news/2018/06/24/poison-hemlock-spotted-in-area-pastures-roadsides-in-tri-state-area/116622512/

Nibalia, E. (2018, July 5). Garden Q&A: How to get rid of poison hemlock. The Baltimore Sun. https://www.baltimoresun.com/features/home/bs-re-garden-qa-0708-story.html

The post Eat Your Carrots, Just Not This One first appeared on Maryland Invasive Species Council.

Contacts: Judy Fulton, EcoPlant Consulting, judy@ecoplantconsulting.com | Sara Tangren, National Capital PRISM

Asian jumpseed cultivars are often sold or traded as plants native to Maryland. Plant enthusiasts frequently mistake this foreign interloper for a native due to a history of taxonomic confusion in the genus generally, but with our native Virginia knotweed specifically. It also doesn’t help that the two species look a lot alike. As a result, gardeners who think they are buying a native and being ecologically responsible can actually be spreading a highly invasive plant. To make matters worse, gardeners often share this prolific grower with their friends. Asian jumpseed has only recently started to escape into natural areas; so, now is the time to practice “early detection and rapid response” (EDRR). Because May is the month when both the native and non-native species are starting to leaf-out fully, the Maryland Invasive Species Council has selected Asian jumpseed as the May Invader of the Month.

Asian jumpseed (Persicaria filiformis) was once incorrectly considered a variety of Virginia knotweed (Persicaria virginiana) and named Persicaria virginiana var. filiformis or Polygonum virginianum var. filiforme. It is a perennial forb that grows up to 2½’ tall earlier in the summer before flowering. Alternate, simple leaves include a sharply pointed, dark maroon to pink or dark green chevron—an upside-down V. The chevron usually persists but can start fading towards fall. Besides the “V”, plants can have leaves that are either plain green or variegated. When the leaves include whitish-cream coloring, they are offspring of the popular ‘Painter’s Palette’, but more often this cultivar’s descendants have the non-variegated form. Plants with green leaves may also be offspring of the non-variegated ‘Lance Corporal’ or ‘Batwings’. From mid-summer through early fall, very small, crimson to pink flowers bloom, spaced along thin, arching terminal spikes that extend up to a foot above the foliage. Seeds are contained in small, hooked fruits. A single plant can drop many seeds to the ground nearby, or they can “jump” 10’ from the stalk when touched. The hooked fruits can also hitchhike to more distant locations on animal fur or get carried still farther away by water to invade fresh territory.

Virginia knotweed or jumpseed (Persicaria virginiana a.k.a. Polygonum virginianum or Tovara virginiana) is similar to Asian jumpseed in growth habit, height, and seed dispersal mechanisms. However, the native’s chevron has less distinct edges than the well-defined V of Asian jumpseed. Besides, this dark mark appears only on the younger leaves of Virginia knotweed, and then soon fades away as they mature. The chevron is especially noticeable on the first foliage of the year, but also shows in a lighter version on new growth throughout the summer. As the days of spring give way to summer, a subtle difference in leaf shape becomes apparent: leaves of Virginia jumpseed appear narrower with a more rounded base and elongate tip. Leaves of Asian jumpseed have a more wedge-shaped base and appear broadest closer to the tip. You can see the seasonal progression in the shapes and chevrons from the spring leaves below to the mature leaves above. Virginia jumpseed almost always has greenish-white flowers compared to the Asian’s reddish-pink flowers.

Asian jumpseed, also called Japanese jumpseed, originally came from East Asia (i.e., China, India, Japan, Korea, Myanmar, the Philippines, Vietnam, and the Kuril Islands). Like its native cousin, the foreigner prefers to grow in part shade in very moist to medium-dry soil. You can find the invader massing in forested uplands and floodplains. In the DC-Baltimore Metro area, invasive populations are spreading in Baltimore County, Maryland, and Arlington County, Virginia (Simmons et al. 2020). The invasive is increasingly escaping throughout the mid-Atlantic region, out to Ohio and up to Massachusetts, as well as other locations in the U.S. and Canada (iNaturalist, Weakley’s 2022 Flora).

Wherever this vigorous invasive finds itself, it forms large, dense monocultures that shade out native plants. Because Persicaria species are rarely eaten by wildlife, the invasive easily outcompetes natives more palatable to deer and other herbivores. Due to Persicaria species’ tendency to hybridize, it is also possible that Asian jumpseed could be interbreeding with Virginia knotweed and so altering the native’s genetics. In natural areas, you might find tons of non-variegated plants mixed with a few variegated invasives and even a handful of the Virginia jumpseed.

To keep Asian jumpseed from becoming widely established, resist the temptation to plant it. Instead, the deer-resistant Virginia jumpseed can serve as an attractive, wild addition to your landscaping. If you already have the invasive in your garden, pull or dig up every one of the plants, preferably before they go to seed. And try to convince your friends likewise. You will not be able to keep Asian jumpseed from escaping from your yard because animals will carry it to other locations. In natural areas, practice Early Detection and Rapid Response by learning how to recognize the invasive, reporting it via EDDMapS, and removing the interlopers you find. Although individual specimens are relatively easy to remove, roots and all, it is amazing how quickly the plants become unmanageable. The infestations that form in just a few years might require too much time and effort to control by hand. For these, a systemic herbicide might be the only option.

References:

A.S Weakley and the Southeastern Flora Team. Ed. April 24, 2022. Flora of the Southeastern United States. Produced by M.T. Lee from FloraManager database system. University of North Carolina at Chapel Hill Herbarium, North Carolina Botanical Garden, University of North Carolina at Chapel Hill. ncbg.unc.edu/research/unc-herbarium/flora-request.

iNaturalist. iNaturalist, LLC. Accessed on 5/14/2022. inaturalist.org.

R H. Simmons, W.C. Taylor, M.E. Farrah, J.S. Graham, and J.P. Fulton. 2020. Noteworthy Collections: Maryland and Virginia. Castanea 85(2): 277–284. https://bioone.org/journals/castanea/volume-85/issue-2/0008-7475.85.2.279/Noteworthy-Collections-Maryland-and-Virginia/10.2179/0008-7475.85.2.279.short.

Early Detection and Distribution Mapping System (EDDMapS). University of Georgia, Center for Invasive Species and Ecosystem Health. eddmaps.org.

The post Don’t Jump to Conclusions about Asian Jumpseed first appeared on Maryland Invasive Species Council.

Knotweed, which was introduced as an ornamental and for erosion control in the late 1800’s, has spread throughout Maryland. The knotweed found in Maryland is usually Fallopia japonica but Fallopia sachalinensis occurs sporadically. A hybrid between the two, Fallopia bohemica also now occurs. Japanese knotweed, Fallopia japonica, is prevalent throughout Maryland, occurring in all counties, while giant knotweed, Fallopia sachalinensis, and possibly Bohemian knotweed, Fallopia bohemica, are also present in more than half of Maryland’s counties. All three species share the same invasive characteristics.

 The plant can produce viable seed depending on environmental conditions but the primary mode of dispersal is vegetative. Even small pieces of rhizomes root easily, and will colonize river banks to the exclusion of other plants. Because it has no fine root structure, it is a poor soil stabilizer and affects species composition and habitat quality along riparian corridors.  The plants prefer sunny, open locations such as river banks or highway right-of-way corridors. Once established, the plant is difficult to eradicate or control. Currently chemical controls with herbicide treatments are the best way to manage smaller patches of the plant. However combating a plant that is considered one of the world’s worst weeds, means using a number of tools, including biological control.

Knotweed psyllid has been released in parts of the UK, and in Canada. Permitting was finally granted for US releases in 2020. Early data from the Pacific NW and some Eastern US states have been mixed on the initial success of the psyllid. Often the success of bio control agents takes several years of releases, for establishment as well as experimentation with release protocols. The psyllid does successfully overwinter in a number of different substrates and is effective at stunting early vegetative growth of knotweed. All life stages, except the egg, feed on knotweed with piercing sucking stylet mouthparts. The psyllid can inflict fatal feeding damage, especially on young growth. Feeding signs are deformed and curled leaves that eventually brown and die.

Currently the MDA lab in Annapolis is successfully raising the Kyushu strain of knotweed psyllid. The psyllid is in the order Hemiptera or “true bugs”, and goes through a gradual change with no pupal stage. Like most bugs they start as a very tiny egg and pass through 5 nymphal stages, slowly gaining an adult appearance. Adults have clear wings marked by varying degrees of dark mottling. Late season psyllids respond to decreasing day length by darkening and will overwinter as adults in tree bark or even in woody debris and mulch.

Maryland is joining numerous other state and federal agencies in releasing the knotweed psyllid, including neighboring West Virginia and the C & O Canal National Park which runs through large portions of Maryland.

The post Unravelling Maryland’s Knotweed Problem, One Psyllid at a Time first appeared on Maryland Invasive Species Council.

Attention anglers!  What lies in your bait bucket has the potential to damage Maryland’s waters and the quality of your most prized fishing hole.  Your favorite type of bait may help you catch a big fish, but it may also be an invasive species.  Rusty crayfish, fathead minnow, goldfish, red swamp crawfish, banded darter, virile crayfish, red wigglers, rainbow darter, and nitro-worms, to name just a few of the non-native bait species that have been used in Maryland waters, are now established in the state.  Some of these introductions have caused little harm, while others have caused considerable ecological damage.  Many other bait species and bait-related diseases are threatening to join the list of Maryland invaders.  With the 2021 fishing season underway, your actions can make the difference and help prevent further introductions of invasive bait species.  For this reason, the Maryland Invasive Species Council has chosen live bait as the July 2021 Invader of the Month.

Dumping unused bait into a stream, river, lake, or on shore is often viewed by anglers as humane or even beneficial to game fishes.  However, this simple act can have unexpected repercussions.  The release of live bait by anglers has been responsible for the introduction of invasive crayfishes, fishes, earthworms, and fish diseases across the nation.   Following their introduction, invasive bait species can quickly overpopulate invaded areas and reduce native biodiversity, water and habitat quality, and cause dramatic changes in ecosystem function.   These changes can cascade through an aquatic food web, affecting everything from algae to commercially and recreationally important fishes.  Even a benign-looking earthworm can have ecological impacts.  Dramatic changes to forests of northern North America have been linked to invasive earthworms such as Lumbricus terrestris, a European species commonly sold as bait.  These invasive earthworms alter soil chemistry, reduce the diversity of other invertebrates, amphibians, and native vegetation, and hasten the spread of invasive plants.  At least nine non-native earthworms have been introduced in Maryland – many of these are common bait species.  Some of these have impacted Maryland ecosystems (see Invader of the Month https://mdinvasives.org/iotm/april-2015/).

The earthworms, crayfishes, and fishes used as bait are not the only concern.  Even the packing material within a bait container can harbor small invaders.  For example, live bloodworms are a popular bait among anglers targeting spot, croaker, striped bass and other fishes in the Chesapeake Bay and its tributaries.  Bloodworms used by anglers in the bay and Mid-Atlantic region originate from coastal Maine where they are harvested from intertidal mudflats, packed in seaweed known as wormweed, and shipped to bait dealers worldwide.  A recent study of the bloodworm trade conducted by scientists at the Smithsonian Environmental Research Center found that a wide variety of small snails, crabs, isopods, amphipods, and other invertebrates live among the wormweed and can survive the transit from Maine to Maryland hidden within a bloodworm bait container.   Anglers who chose to dump their unused worms as well as the wormweed from their bait containers into Chesapeake Bay waters may unknowingly introduce another problematic, invasive species. 

Photo Credit:  Dr. Amy Fowler – George Mason University

Bloodworms, a common bait used in the Chesapeake Bay, are often imported in containers of wormweed (pictured here) from the coast of Maine. This wormweed can contain a wide variety of other non-native, potentially invasive ‘hitchhikers’ that could pose a risk if discarded in Maryland waters.

Parasites, fungi, fish pathogens, and other microscopic organisms associated with live bait can dramatically reduce the health of anglers’ favorite game fishes.  For example, Viral Hemorrhagic Septicemia (VHS) is a highly contagious disease that has caused massive fish kills in the Great Lakes since 2005 and has spread to other waters in New York, Ohio, Wisconsin, and Michigan.  This disease  infects over 40 species of fishes including rainbow trout, brown trout, walleye, yellow perch, channel catfish, northern pike, and black crappie.    The use and release of contaminated bait is believed to be one of the important vectors responsible for the spread of this disease.  To prevent its spread, natural resource agencies and bait dealers in the Great Lakes region have taken steps to prevent the culture, sale, and export of contaminated bait. 

Fortunately for Maryland, these actions should greatly reduce the likelihood that VHS hitchhikes make it into the state on contaminated bait.  However, complete protection of our waters from invasive bait species and from fish diseases like VHS requires an informed and vigilant angling community here in Maryland. Your actions can make all the difference. 

You can help prevent the spread of invasive bait species by doing the following:

• Never release unused live bait and packing material directly into water or on shore
• Give your unused live bait away to other anglers
• Save your bait for your next fishing trip
• Dispose of your unused live bait humanely by placing it in a freezer
• Never carry organisms from one watershed to another

And most importantly, spread this message to your fellow anglers.  Give them this information and tell them to pass it on!

For more information on invasive bait species and Maryland’s bait regulations, visit http://www.dnr.state.md.us/invasives/

Originally posted as the Invader of the Month in April 2011.  Updated May 2021.

The post Take the Bait…don’t dump it! first appeared on Maryland Invasive Species Council.

We may be under a stay-at-home order, but the natural world is on the move as spring comes into full swing. Unfortunately, that includes invasive species. One invasive threat, that has been on the move in Chesapeake watershed since the 1960s, is invasive catfish. Sightings and catch of these fish pick up each spring as more anglers start hitting the water. As fishing season kicks into gear, we picked blue and flathead catfish as the April Invaders of the Month.

Both flathead and particularly blue catfish are considered good recreational fish. They offer some challenge when catching and good eating. That’s why these invasive catfish were introduced to the James and Rappohanok rivers in the 1960s. Both species are native to the central US in the Mississippi, Ohio and Missouri river systems. From the initial introduction in the James and Rappohanok, the blue catfish has spread to the Potomac and eventually to every major tributary of the Chesapeake Bay. Flathead has spread less, but can still be found in the Potomack, Elk, and Sassafrass rivers. 

Predation is the main threat of invasive catfish to our native species and ecosystems. While most of the catfish diet consists of vegetation, it does prey on important and imperilled animals in the bay. Menhaden, American shad and other fish make up small portions of the blue catfish’s diet. In areas with higher salinity, blue crabs can make up a significant portion of their diet. Despite the fact that predation is not heavy on many natives, any amount can be detrimental to commercial fisheries, recreation, and restoration efforts.

Both invasive species can be distinguished from our native species with relative ease. The blue catfish has smooth blue-slate skin and can grow quite large. The record size catch of blue in Maryland is 84 pounds, versus the record 9.6 pound native white catfish. Flathead catfish, though not as large as blue catfish, is also significantly larger than native catfish. Flatheads generally look more similar to yellow and brown bullheads than white catfish. However, flatheads have a projected lower jaw unlike the bullheads.

When we are able to head out again, all of us anglers can do our part to help control these invasive catfish. Catch them! The Maryland Department of Natural Resources asks anglers to remove and kill any blue and flathead catfish they catch. Catch and release of these fish is discouraged, as they are invasive predators and pose a serious long-term threat to our native species. It is also illegal to transport live blue and flathead catfish into another body of water. If you don’t fish, you can always eat them!

For more information, visit:

https://dnr.maryland.gov/fisheries/Pages/catfish.aspx

https://dnr.maryland.gov/fisheries/Documents/Invasive_Catfish_%20Fact_Sheet.pdf

The post Colossal Catfish Cause Conservation Complications first appeared on Maryland Invasive Species Council.

As temperatures begin to rise and we start looking for signs of spring, don’t be fooled by these little yellow beauties as you stroll through the woods looking for wildflowers. Lesser celandine (Ficaria verna), is a member of the buttercup family and more commonly known as fig buttercup. It is a non-native invasive that will quickly out-compete our native spring ephemerals and many more native plants in our natural areas. Introduced into the United States in the late 1800’s from Europe and parts of northern Africa and Asia as an ornamental, this plant creates thick mats across the forest floor, crowding out other vegetation above ground, and growing tubers below ground that compete with plants for root space. The plants are highly visible in early spring, which is why they have been selected as Maryland Invasive Species Council’s March Invader of the Month.

The attractive bright yellow flowers have eight to 12 petals and are about 3 inches across, blooming from late winter to early spring. After flowering, the shiny, dark green kidney-shaped leaves carpet the forest floor until the mid-summer. The thick tuberous roots, about a half an inch each in size, form a dense network below the soil surface. By June, the foliage has died back, and the plant becomes dormant, though the tubers continue to occupy root space below ground year-round. Lesser celandine primarily reproduces through these underground tubers, so disturbance, including pulling, flooding and digging by animals can result in further spread of the plant.

Because lesser celandine emerges so early, it can out-compete many native ephemerals, taking advantage of early-season sunlight before trees begin to leaf out. The resulting dense mat formed will shade our native spring wildflowers, preventing them from emerging, and likewise disrupting native pollinators searching for early-season nectar sources. 

Lesser celandine can be controlled chemically or manually. For chemical removal, a 1-2% glyphosate solution can be applied during the active growing and blooming period, between February-March when temperatures are above 40^oF. Spraying during this time will minimize killing other native plants in the vicinity as most should not have emerged yet, but precautions should still be taken to minimize spraying non-target plants. Manual or mechanical removal of small infestations can be successful but removing all the below ground parts is critical. This plant will readily reproduce vegetatively, so any missed roots or tubers can produce new plants. 

To help ensure long-term success, after removing lesser celandine, replant the area with natives, which will to help control soil disturbance and replenish an important nectar source for insects. Lesser celandine is often confused with a desirable native wetland plant called marsh marigold (Caltha palustris). While they have similar leaf shapes and color, marsh marigold flowers only have five to nine petals and the plant does not produce tubers. Other native alternatives to consider include wild ginger (Asarum canadense), bloodroot (Sanguinaria canadensis), twinleaf (Jeffersonia diphylla), cutleaf toothwort (Cardamine concatenate), Dutchman’s breeches (Dicentra cucullaria), Virginia bluebells (Mertensia virginica) and golden ragwort (Packera aurea). 

Maryland banned the sale of lesser celandine beginning in 2017.  However, it may still be commercially available in other states, and all varieties should be considered invasive.

For more information, please visit:

Brandywine Conservancy

Ecosystem Gardening

Plant Invaders of Mid-Atlantic Natural Areas

The post Deceptive little buttercup is foe, not friend first appeared on Maryland Invasive Species Council.