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.

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Agenda:

MISC meetings are open to the public.

Next meeting: April 17, 2025
Location: Dept. of Natural Resources Headquarters, 580 Taylor Ave, Annapolis, MD 21401

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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.

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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

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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.
  
  

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