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.

With smooth grey bark and bronze leaves lasting deep into winter, the American beech (Fagus grandifolia), is a popular and easily recognizable tree in the eastern forest. It is an ecologically important tree, as it is one of the lone hard mast producers and a climax species of the northern hardwood forest. For over a century, this species has been under threat from beech bark disease. Partially caused by the invasive beech scale insect, the disease was discovered in Nova Scotia in 1890 and has since spread to most of New England and beyond. Beech bark disease has had a devastating impact on beech trees, but there is a newer threat to this species that has researchers on the lookout – beech leaf disease (BLD). As beech trees are so visible this time of year, beech leaf disease has been selected at MISC’s February IOTM.

In 2012, a number of trees in Lake County, Ohio were found with distinct symptoms on their leaves, marking the discovery of beech leaf disease. The symptoms of beech leaf disease were not seen on any other beech trees in the U.S. or the rest of the world. This led biologist John Pogacnik, the discoverer of BLD, to believe that it may be caused by local weather stresses or other abiotic factors. However, after observing the exponential rate of spread, it was determined to have a biotic cause. 

By 2014, the disease had spread to three new counties in Ohio. In 2018, signs of beech leaf disease could be found in 24 counties in Ohio, Pennsylvania, New York and Ontario. While the spread has been rapid, the effects have not been entirely consistent; areas like Lake County have seen nearly all trees infected but to varying rates of decline. Hopefully, this bodes well for disease resistance and, if necessary, breeding a resilient population.

The disease can initially be identified by the darkening bands between the leaf veins, which appear in spring and can still be seen on bronze winter leaves. Later symptoms include the total darkening (while still not crossing the veins), shrinking and ruckling of the leaves. The leaves in the second stage of symptoms are thicker and leathery in the darkened areas.  Symptoms generally start at the lower portion of the tree, working up to the crown. After the leaves are affected, buds can be terminated, leading to dieback, decline and possibly death. Mortality is more likely to be seen on saplings and young trees, though limited mortality has been observed on larger trees. 

The cause of the disease, whether a complex or single agent, is not yet determined. At Ohio State, research is underway, comparing DNA found in infected trees to uninfected ones. Any differing results could point to the cause. The Ohio Department of Agriculture has also found Litylenchus nematodes on infected leaves, though more research must be conducted to determine if they are the sole cause of beech leaf disease. Litylenchus crenatae nematodes are found on beech trees (Fagus crenatae) in Japan. The species was described in 2018, and the American population has since been described as a subspecies.

In Maryland we are a good distance from infected areas, and there is still hope that we won’t see the disease spread to us. However, it’s good to keep a watchful eye and stick with best management practices, like not moving firewood. If you think you see signs of beech leaf disease in your area, contact: Forest Pest Management at 410-841-5922. 

Photo Sources:

Jim Chatfield, OSU Extension, https://bygl.osu.edu/node/1176

Sources

Ewing CJ, Hausman CE, Pogacnik J, Slot J, Bonello P. Beech leaf disease: An emerging forest epidemic.  For Path. 2019;49:e12488. https://doi.org/10.1111/efp.12488 

Popkin, G. (2018). An arboreal murder mystery: What is killing beech trees? The Washington Post. Retrieved from, https://www.washingtonpost.com/national/health-science/an-arboreal-murder-mystery-what-is-killing-beech-trees/2018/07/27/95d18ebc-8c59-11e8-a345-a1bf7847b375_story.html 

Wike, C. (2019) A Mysterious Disease is Killing Beech Trees The Scientist Retrieved from, https://www.the-scientist.com/news-opinion/a-mysterious-disease-is-killing-beech-trees-65358

More information:Beech Leaf Disease – Ontario’s Perspective: Dr. Sharon Reed https://www.youtube.com/watch?v=tDBbik7cUrI

The post “New Leaf Disease is a Beech” first appeared on Maryland Invasive Species Council.

Many of us have grown up thinking that earthworms are a sign of healthy, fertile soil. However, many earthworms found throughout Maryland are not native. Earthworms can be beneficial in their native ecosystems and agricultural settings, but their ability to re-engineer soil can completely restructure ecosystems and the microbial, plant, arthropod and vertebrate communities that live within them.  Much of what we know about invasive earthworms comes from studies of invasive European earthworm species, whose effects on forests are particularly notable in temperate North America. More recently, ‘jumping worms,’ (the common name for several similar-looking species belonging to the family Megascolecidae, also known as crazy worms, snake worms, Alabama jumpers, Jersey wigglers, Georgia jumpers, pheretimoids), have invaded temperate and tropical ecosystems across the globe. Their distribution is patchy throughout North America, and while often associated with urban and suburban landscapes, they are appearing with greater frequency in natural areas and forests. Once introduced to a location, jumping worm populations grow rapidly, and can grow to high densities in 4-5 years. Due to their ecological, economic and recreational impact, and the difficulty in removing them once they have been established, jumping worms have been chosen as MISC’s Invader of the Month for November.

Figure 1. Jumping worms alter soil characteristics, increasing erosion (left) and creating large macro aggregates (right). (Annise Dobson)

Jumping worm invasions are unique in that they consist of multiple co-invading species including Amynthas agrestis, Amynthas tokioensis, and Metaphire hilgendorfi in temperate North America. Jumping worms grow and mature quickly, and some species can reproduce asexually, thereby quickly reaching high densities from an initially small invading population. They grow and mature much more quickly than European or native earthworms. While both lumbricid and jumping worms remove the organic horizon, the texture of jumping worm invaded soils is more stressful for roots, fungi and soil fauna. This is because jumping worms transform surface soils into large macroaggregates, described as ‘gravely,’ with the appearance of ground beef or spent coffee grounds. These changes to soil lead to erosion, nutrient leaching, root desiccation, and plant death (Fig 1).

The cascading effects of jumping worms on other species are far reaching. In areas of heavy infestation, anything that relies on the forest floor for food and habitat, such as soil fauna, native plants, salamanders, birds and other animals decline. Furthermore, jumping worm tissues can accumulate toxic metals, suggesting they could be a major pathway for metal bioaccumulation in higher organisms. In addition to deteriorating natural systems, jumping worm impacts are being felt by gardeners, plant nurseries, golf courses and community parks. The deep layer of loose castings created by jumping worms is particularly problematic for perennial plants (both native and horticultural), as well as parks and lawns used for recreation.

Jumping worms can be identified all year round by the distinctively granular soil, described as looking like ground beef or coffee grounds. Their presence can be confirmed in late summer when populations grow rapidly, reaching peak size and abundance. Key features include:

• Thrashing behavior and high densities
• Smooth, metallic sheen, often darkly pigmented, and 1.5 to 8 inches long
• Clitellum often cream colored and goes all the way around the body, unlike the lumbricid species which have a raised and pink colored clitellum (Fig. 2)

Because we currently lack any viable control strategies, efforts should be put on limiting  

human-mediated dispersal of adults and cocoons. Fortunately, the worms don’t move very quickly on their own! Best practices include:

• Require clean equipment provisions in logging and landscaping contracts (and encourage your neighbors and local government to do the same
• Treat compost and mulch to 55 ^oC for 3 days
• Prevent dumping of yard waste
• Plant bare-root
• Don’t move soil in tools, equipment, shoes
• Don’t dump bait or compost worms
• Don’t use compost and mulch of unknown origin

For more information see

https://dnr.wi.gov/topic/invasives/fact/jumpingworm/index.html

http://blog.uvm.edu/jgorres/amynthas/

The post The visible invisible: impacts of invasive jumping worms first appeared on Maryland Invasive Species Council.

Invasive vines are colorful and decorative plants that are often used for ornamental purposes for their showy flowers and colorful, sometimes uniquely shaped fruit. They have a downside however, as many invade forested habitats where they can severely limit the growth of, or even kill, trees and shrubs. Fall is a great time to control invasive vines. For this reason, invasive vines are the October Invader of the Month.

Vines are fascinating plants that have evolved a unique strategy that allows them to compete with larger woody plants. Vines use other plants for support to reach sunlight and further their growth, foregoing the need for large root systems and sturdy stems to keep them upright. This ability to climb allows them to grow rapidly and maintain a narrow and flexible stem. The stem of a typical vine has larger vessel elements or water conducting tissue that allows it to bring water to the upper reaches of the plants. It most importantly allows the plant to support more leaves than a tree with a similar sized stem. Vines have been observed to comprise 40% of the total leaf surface area of a forest while accounting for only 5% of the above ground biomass.

Vines are for the most part light loving plants. They grow in the open or on the edges of forests where light is more abundant and where they can find trees for support. They usually start by themselves and will grow toward any objects that can climb. Vine climb by several methods. Some use tendrils or rootlets to latch onto the tree or shrub to hold it as it grows. Others use phototropism to climb by winding around the stem it is climbing. This is called circumnutation. Once they reach the top they will often send out growth looking for adjacent tree to expand to.

There are native vines in the eastern forest. Wild grape(s), poison ivy, and Virginia creeper are the most common ones encountered. All are valuable as providers of grapes or berries for wildlife such as birds and many mammals including foxes, raccoons, and opossums. These vines do climb trees and shrubs to reach light, like invasive vine species but differ in one key characteristic. These vines do not use circumnutation as they climb the tree; instead they use tendrils or modified roots to attach to the tree. Non-native vines like Asiatic bittersweet, Japanese honeysuckle and Japanese and Chinese wisteria do twine around the tree and eventually strangle the stem and kill the tree. This is a serious problem with young and regenerating forests as the seedlings and sapling are killed before they can become established as the replacement for the next stand of trees.

Another way vines can be damaging is by smothering a tree. Once reaching the top of the tree, vines continue to grow covering the crown of the tree and blocking light from reaching the leaves. They often grow across gaps in the canopy and latch onto the adjacent tree. The vine also adds considerable weight to the crown and will often cause trees to collapse under the extra weight. No vine is more capable of this than the legendary Kudzu vine, often called the vine that ate the south. Kudzu will continue to grow until it covers any stationary object including buildings and abandoned vehicles. Kudzu transforms the habitat of an area by creating a blanket of leaves and vines that doesn’t allow other plants to grow. Kudzu, once planted to control erosion has been found to not have a controlling effect on erosion as the stems and leaves are perched above the ground and aren’t in contact with the soil.

Invasive vines also have negative effects on wildlife habitat. Asiatic bittersweet berries are only half as nutritious as those from the native American bittersweet. This has implications for migratory birds that also depend on this food when migrating south in the winter. There is also concern that rising CO² levels associated with climate change will stimulate greater growth of these invasive plants.

Getting control of vines can be difficult. Some vines like Kudzu usually require herbicides to kill. Most produce abundant amounts of seed and develop a seed bank from which seedling will sprout for many years. Mechanical control can work if persistent effort is made to repeatedly cut them until the roots are exhausted of food reserves. The most common method is to cut a “window” in the vine, severing it at the base of the tree, and then again several feet up, to prevent re-attachment. English ivy, one of the most notorious invasive vines in the mid-Atlantic, area can be dealt with mechanically by cutting the vines at the base of the tree and allowing the growth on the tree to wither and die. Pulling English ivy from the trunk can damage the tree or cause dead branches to fall so it’s best to leave it on the tree. The vines on the ground can often be easily pulled up. Again, persistence is required. It’s also important to not let the cut stems lie in contact with the ground. They can root themselves and become reestablished. Instead bag them, and either take them to the landfill, or store them for several months until you are certain they are dead before composting. Beware of the seeds too. They can persist for years.

An important thing to remember is to not plant invasive vines. Many are available for sale in local nurseries. Instead look for native alternatives. Be aware of things like Christmas wreaths made of bittersweet vines. They often have berries on them that can germinate if disposed of carelessly. The good news in the fight against invasive vines is that persistence will lead to success. The challenge is there and real, but it is not hopeless with dedication and application of sustained effort.

The post The Sign of the Times are the Vines first appeared on Maryland Invasive Species Council.

ANNAPOLIS, MD (August, 2019) – Thousand cankers disease (TCD) is a complex problem in walnuts, Juglans spp., caused by the fungus Geosmithia morbida and transmitted by walnut twig beetle (WTB), Pityophthorus juglandis. The beetles tunnel under tree bark and introduce the fungus, causing cankers that eventually coalesce and girdle limbs and branches, resulting in tree death. Walnut twig beetle was first identified in 1928 in Arizona, in Arizona walnut, Juglans major. Slowly, the beetle has spread to other areas of the U.S., including several states in the Northeast. Black walnut, Juglans nigra, began to show widespread decline in the 1990’s. The first cases of black walnut mortality with bark cankers were found in Denver, CO in 2001, and the association of the Geosmithia morbida fungus with these cankers was identified around 2008. By then, nearly all black walnuts in the Denver area were affected. TCD has now been confirmed in MD, VA, PA, and several other neighboring states (Figure 1). 

WTB feeds in the cambium and phloem of larger twigs, branches, and main stem of Juglans and Pterocarya spp. to create brood galleries beneath the bark. As WTB create galleries, they inoculate the phloem with Geosmithia morbida. The fungus colonizes and kills the surrounding cambium and phloem tissue. Cankers form around every beetle feeding site, which may coalesce to form larger ones, eventually leading to tree death. Generations of the beetle move to and from black walnut trees carrying the fungus to the next hole or tree as they create galleries. 

Walnut twig beetle attacks all species of walnut and wingnut (Pterocarya). A considerable range of TCD susceptibility exists among various walnut species, with black walnut being particularly susceptible. As cankers grow within the phloem of black walnut, they reduce the tree’s ability to store and move nutrients. As TCD progresses, cankers coalesce to girdle branches. As the tree weakens, more bark beetles are attracted and more cankers are formed, eventually killing the tree. It may take several years of insect attack and fungal infection before symptoms other than minute exit holes of the beetle on the trunk are visible.

Walnut twig beetle is 1.5 to 2 millimeters long, has a relatively narrow body is reddish-brown to brown cuticle (Figure 2). It makes tunnels beneath tree bark. In such case, the outer bark can be peeled away to expose WTB galleries in the phloem, a key feature for diagnosing the TCD complex (Figure 3). Cankers become oval-shaped and inky black, reaching more than 3 cm in length. However, the bark remains firmly attached to the canker face, making necrotic areas very difficult to observe. Numerous cankers are present in a single tree due to multiple points of pathogen introduction. Small pin-sized holes are associated with each canker, usually denoting the entrance/exit hole for the WTB. Cankers often bleed, leaving dark ooze and staining on the outer bark surface. 

Symptoms start with leaf yellowing and crown thinning of infected trees, which may initially be restricted to a single branch. As the disease progresses, foliage wilts, larger branches die, and eventually the tree dies. In susceptible hosts, trees are typically killed within 2–3 years after external symptoms of leaf yellowing are first observed. TCD was first detected in Maryland in October 2014 and a quarantine was ordered by the Maryland Department of Agriculture to minimize the risk of disease spreading from Cecil County. The beetles were collected from traps in Baltimore in August 2017. On May 1, 2019, a new quarantine order was issued to restrict the movement of infected materials in all of Baltimore City and part of Baltimore County (Figure 4). Introduction of TCD to a new area involves transportation of infected logs, trees, or other untreated wood products which may carry the beetle or fungus. Quarantines restricting the movement of these products help to limit long distance dispersal and manage this disease.

For more information:

Maryland Department of Agriculture, May 1 2019. Thousand Cankers Disease Detected in Baltimore City and County. https://news.maryland.gov/mda/press-release/2019/05/01/thousand-cankers-disease-detected-in-baltimore-city-and-county/

C. Nischwitz and M. Murray. 2011. Thousand cankers disease of walnut (Geosmithia morbida). https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1729&context=extension_curall

US Department of Agriculture: https://www.invasivespeciesinfo.gov/profile/thousand-cankers-black-walnut-disease

Maryland Department of Agriculture: https://mda.maryland.gov/plants-pests/Pages/tcd.aspx

The post Thousand Cankers Disease Reappears in Maryland first appeared on Maryland Invasive Species Council.

ANNAPOLIS, MD (December 1, 2015) – Exotic species are in the news almost daily. They can be found in our parks and even in our own backyards. Sadly, many of them are so common, most people do not realize that they do not belong here. To be invasive, an organism must have evolved somewhere other than where it's found in Maryland, have a negative impact on the environment it moves into, and have been moved, deliberately or by accident, by people.

For example, when the brown marmorated stink bug silently slipped into the U.S., it was years before it was correctly identified as an exotic species. By that time it was already becoming a pest in orchards and vineyards.

One of the first questions about most invasive species is "How did it get here?" — quickly followed by "Could it have been prevented?" The majority of invasive plant seed, disease and insect pests are accidentally introduced. How, you might ask? While the list of pathways is surprisingly long, the most common avenues are the movement of goods produced in foreign countries, travelers returning home with souvenirs, and internet sales. The U.S. Department of Agriculture (USDA) and Customs and Border Protection (CBP) work to prevent the introduction of such pests. In this month of increased holiday travel by both people and packages, the Maryland Invasive Species Council has chosen this prevention work as the topic for the December's "Invader of the Month".

Cargo is moved in large containers with products shrink-wrapped on pallets, in boxes, or simply loaded in trucks. This results in many small hiding places that insects, seeds, and snails can use to move, unbeknownst to them, all over the world. To prevent this from happening, CBP, a branch of the Department of Homeland Security, routinely inspects cargo. The searches are extensive and include examining the exterior of shipping containers for hitchhikers adhering to the undercarriage and walls. Inside the container, pallets are checked to ensure that they have been properly treated to prevent the movement of bark beetles and woodborers. Inspectors then move to the product being shipped. Flashlights, forceps and box-cutters are routinely used to open, inspect, and manipulate the products to ensure they are pest free. The final stage of an inspection is to sweep out the empty cargo container and look for any seeds or insects that were hiding in the corners.

Most people love escaping on vacation, but if you have ever traveled internationally you might recall filling out a declaration form before leaving the faraway airport to return home. Preventing the movement of pests in baggage is challenging and relies on several factors, including the declaration form. The declaration is a reminder to all passengers entering the US that bringing in certain items is prohibited. The declaration is a federal form and false claims are subject to penalty. To reinforce the urgency and in an attempt to keep people honest, CPB randomly selects passengers for screening, checks passenger lists against a database of previous violators, and walks the baggage floor with highly trained K9 units.

The last pathway of pest introduction is internet sales. The internet has drastically increased the average person's ability to buy products, knowingly or not, from foreign countries. Foreign markets are trying to meet the high demand for heirlooms and specialty varieties and non-GMO seeds for home gardeners. Small packets of seeds are easily mailed and are found only by hard work and highly trained K9 Units. Unfortunately, a recent study reports that our current biosecurity practices are not effectively preventing the trade of plant material via internet sales (Humair et al. 2015).

You can contribute to the economic and ecological safety of the US and your own backyard by being a careful and conscientious traveler and internet purchaser. Know what you're importing, where it comes from, and make sure it's legal.Given the sheer volume of cargo, baggage and mail entering the US on a daily basis, it is unrealistic to believe that every pest will be found. Pests such as the tomato leaf miner (Tuta absoluta), wheat bug (Nysius huttoni), oak ambrosia beetle (Platypus quercivorus) and Asiatic brown rot (Monilia polystroma) are known threats. Unfortunately there are hundreds of species like them that not only threaten our neighborhoods but the entire U.S. economy. In response to this ongoing threat, the US Department of Agriculture (USDA) has established several programs to eradicate, or at least mediate the impacts of, new pests. Examples of this work include recalling products found to be infested or in violation of federal regulations, conducting surveys in and around the ports where cargo first enters the US and pests are most likely to establish, and providing funding to perform trapping across the country for high risk pests.

For more information about Invasive Species of Concern in Maryland, visit the Maryland Invasive Species Council.

photos available electronically on request.

References

Humair, Franziska, Luc Humair, Fabian Kuhn and Christoph Kueffer. 2015. E-commerce trade in invasive plants. Conserv. Bio. (in press)

US Department of Homeland Security, U.S. Customs and Border Protection. CBP Form 6059B (04/14)

Additional Resources

Animal and Plant Health Inspection Service

The post Preventing Invaders first appeared on Maryland Invasive Species Council.

Contact: Dana Limpert, Conservation Specialist, MD Department of Natural Resources Wildlife and Heritage Service | DanaL.LIMPERT@maryland.gov

ANNAPOLIS, MD (February 1, 2015) – White nose syndrome (WNS or PD, Pseudogymnoascus destructans*) was first confirmed in Maryland bat overwintering hibernacula in 2010. The disease has been documented in all major bat hibernacula in Maryland with the exception of three abandoned railroad tunnels in Allegany County. During the winter of 2014, Maryland biologists participated in a nationwide study that involved using swabs to take skin samples from live bats in the tunnels and the surfaces upon which they were found. Analysis of the Maryland samples indicated that the tunnels and bats were fungus-free. Although these results continue to be puzzling to researchers, we hope to find disease-free bats again this winter. Because Maryland DNR is about to begin the 2015 bat survey, the Maryland Invasive Species Council has designated white nose syndrome fungus as the February Invader of the Month.

White-nose syndrome was first discovered in a cave near Albany, New York in February 2006. WNS has been confirmed or suspected in 25 eastern and Midwestern states south to Mississippi and five eastern Canadian provinces. The cold-loving fungus attaches to the skin surfaces of hibernating bats, ingesting skin and irritating them to the point that they arouse more frequently from hibernation than healthy bats, forcing them to use up fat reserves before winter is over. As a last ditch effort to avoid death, the starving bats fly out of the hibernacula in search of insects (which are not present in the winter) and soon die. Studies also indicate that the fungus causes severe physiological imbalances and inhibits proper body functions due to skin damage, especially on the wings. Biologists estimate that 5.7 million bats in the eastern U.S. have died, with documented declines of 90-100% in WNS-affected hibernacula.

Biologists suspect that the WNS fungus is a non-native pathogen recently introduced to the United States from Europe, where bats have developed immunity. Although bats can transmit the disease to each other, it is hypothesized that the fungus came to the United States on the boots or clothing of humans frequenting caves and using the same clothing and equipment without decontaminating between caves. The bat species confirmed with WNS nationwide are big brown bat (Eptesicus fuscus), Eastern small-footed bat (Myotis leibii), endangered gray bat (Myotis grisescens), endangered Indiana bat (Myotis sodalis), little brown bat (Myotis lucifugus), Northern long-eared bat (Myotis septentrionalis), and tri-colored bat (Perimyotis subflavus).

Maryland DNR biologists monitored Maryland bat hibernacula containing the fungus from 2009 to 2014, and reported the following precipitous declines in hibernating bats populations: 98.2% tricolored bats, 99.5% little brown bats, 100% northern long-eared bats, and 28.3% big brown bats, species which once were the most common bats hibernating in Maryland. Following the lead of other WNS-affected states, DNR hired Appalachian Lab researchers to conduct acoustic bat detector summer surveys in 2010 through 2013 in western Maryland. Acoustic surveys involve using special microphones that can detect bat echolocation calls, which are then saved automatically to a computer hard drive for call identification and analysis later in the lab. From 2010-2013, bat calls decreased by 31.5%, with a 79.9% decline in tricolored bat calls, 82.4% little brown/Indiana bats, and 64.4% Northern long-eared bats. Surveys done the summer of 2014 are still being analyzed, but these surveys clearly provided sad supporting evidence of dramatic declines of hibernating bat species.

There is some good news. Bat biologists in New York and Vermont have banded little brown bats and discovered that up to 50% of little browns are returning to test sites having survived the winter in recent years. These findings give hope that some individuals will survive and that the species will eventually recover. It is important to mention that little brown bat numbers at these test sites still remain at less than 10% of the population size prior to WNS introduction.

Interestingly, there are bat species which have been detected with the WNS fungus which have had no confirmation of disease: Eastern red bat (Lasiurus borealis), Southeastern bat (Myotis austroriparius), silver-haired bat (Lasionycteris noctivagans), Rafinesque’s big-eared bat (Corynorhinus rafinesquii), and Virginia big-eared bat (Corynorhinus townsendii virginianus), any of which may occur in Maryland. There is also a federally listed species found in WNS-affected areas that has not yet been confirmed with WNS or fungal infection—the Ozark big-eared bat (Corynorhinus townsendii ingens).

The ecological consequences of this unprecedented loss of bats are unknown. Bats are important predators of night-flying insects, including many species that are pests for people or injurious to agriculture crops and gardens. Researchers have extrapolated from published data that the precipitous decline in North American bats could lead to agricultural losses of more than $3.7 billion annually. A single little brown bat can consume 4-8 grams of insects each night during its active season. Extrapolated conservatively to the estimate of one million bat deaths from WNS, this means that between 1.5 and 29 million pounds of insects are not being consumed in areas affected by WNS. The continuing loss of bat biodiversity and bats’ impacts on insect populations make this issue extremely urgent both economically and ecologically.

*formerly Geomyces destructans

For more information, see the U. S. Fish and Wildlife Service Website:https://www.whitenosesyndrome.org/.

For more information about Invasive Species of Concern in Maryland, visitMaryland Invasive Species Council

photos available electronically on request.

The post White Nose Syndrome first appeared on Maryland Invasive Species Council.

ANNAPOLIS, MD (December 10, 2014) – Thousand cankers disease (TCD) is a disease complex first discovered in the western United States that primarily affects black walnut (Juglans nigra). This disease is the result of the combined activity of a fungus (Geosmithia morbida) and the walnut twig beetle (Pityophthorus juglandis). Because the insect and fungus were confirmed for the first time on a site in Cecil County, Maryland in the fall of 2014, MISC has chosen thousand cankers disease as the December Invader of the Month.

Spores of the fungus (Geosmithia morbida) are carried and introduced into the tree by adult walnut twig beetles (Pityophthorus juglandis) during egg gallery construction. The fungus kills the tissues around the beetle galleries, causing shallow dark cankers in the inner tree bark. The beetles attack trees in large numbers, resulting in numerous cankers that girdle branches and disrupt the flow of nutrients throughout the tree. Widespread mortality of black walnut since 2001 in Colorado led to the recognition and description of the disease. The list of confirmed cases of TCD in eastern states has been expanding and currently includes Pennsylvania, Virginia, Tennessee and North Carolina.

Black walnut is an important part of the forests of Maryland. Not a common tree, black walnut is found on moist to mesic sites with best growth in full sun. Black walnut is often found in forest buffers and is widely planted for conservation purposes. The wood is prized for its beauty and used in furniture as veneer and in solid wood construction. It is also a valuable wildlife food with the nuts enjoyed by humans as well.

A black walnut tree can be infected with TCD for many years before showing symptoms, but once branch dieback appears the tree begins to decline and eventually dies. The first symptom to appear by mid-summer is leaf flagging, which includes leaf wilting and yellowing, followed by thinning of the canopy from twig and branch dieback. Eventually the whole tree dies as “thousands of cankers” girdle branches and the trunk.

This disease is very different from Dutch elm disease or oak wilt. Those other insect-vectored fungal diseases only require one introduction of the fungus into the tree, and from there the fungus spreads through the water conducting system of the entire tree. TCD requires multiple introductions of the fungus by the walnut twig beetle to cause dieback.

Currently, there are no effective methods for saving trees with TCD. Prevention starts with stopping the spread of the walnut twig beetle into new areas where it does not yet occur. Keeping a close watch on your walnut trees is crucial. Inspect walnuts regularly during June through early August for symptoms of TCD including:

• Sparse foliage or thinning of the canopy
• Leaf yellowing or wilting or branch dieback
• Presence of tiny beetle holes in bark or galleries in branches or the trunk
• Presence of brown to black tissue surrounding beetle galleries inside the bark
• Epicormic shoot development

Dead and dying branches should be pruned from the tree and the wood destroyed by burning. The beetle spreads to new locations primarily by movement of infested wood materials such as logs, firewood, lumber and wood chips. Movement of nuts is not a concern since TCD is not systemic in infected trees and does not enter the nuts. Trees killed by TCD support development of large numbers of walnut twig beetles. Moving a single log with live beetles can start an outbreak in a new location. There are regulations and quarantines in states with confirmed occurrences of this disease – contact your state Department of Agriculture for information on local regulations.

Additional Resources
Thousand Cankers Disease. Invasive Species of Concern in Maryland

Thousand Cankers Disease (Pest Alert). USDA Forest Service

Walnut twig beetle: update on the biology and chemical ecology of a vector of an invasive fatal disease of walnut in the western U.S. USDA Forest Service

For more information about other Invasive Species of Concern in Maryland, visit the Maryland Invasive Species Council.

photos available electronically on request.

The post Thousand Cankers Disease first appeared on Maryland Invasive Species Council.

ANNAPOLIS, MD (January 1, 2013) – Chronic wasting disease (CWD) is one of several diseases classified as transmissible spongiform encephalopathies, or TSE’s. Scrapie in sheep, mad cow disease (BSE), and variant Creutzfeldt-Jakob disease (vCJD) in humans, are also TSE’s. While humans can contract vCJD from eating BSE-infected beef, there is no evidence that CWD can be contracted from eating infected venison. To date, CWD has only been found in mule deer, white-tailed deer, elk and moose

The Maryland Department of Natural Resources (DNR) has been testing for CWD since 1999. Efforts were increased in 2002 with the discovery of the disease in Wisconsin. As of 2012, over 7,500 deer have been tested for the disease statewide. In recent years, efforts were focused in Allegany County near to where West Virginia discovered the disease in 2005. To date, DNR has detected the disease in one deer. The single positive sample was taken from a 1½ year old buck shot in Green Ridge State Forest during the 2010-11 firearm season, near the West Virginia outbreak; that is why the Maryland Invasive Species Council has named Chronic Wasting Disease as the October Invader of the Month.

While there is still some speculation that CWD can infect humans, there is an increasingly convincing amount of data and research that shows there is no tendency for this disease to ‘jump’ the species barrier. There is hope that CWD is more like scrapie, which was first identified in the 18th century and has never been documented to infect humans. Nevertheless, CWD is a disease to be cautious of and it is appropriate for wildlife agencies across the nation to be vigilant and respond quickly to positive cases.

CWD was formally identified in 1967 at Colorado State University. The disease was discovered in captive mule deer used for research purposes by the university. CWD remained a cervid (deer family) disease of the west until 2002, when it was discovered east of the Mississippi River in Wisconsin. After the Wisconsin discovery, CWD surveillance increased significantly across the country, due largely to federal funding made available by USDA. Since that time, the disease has been discovered in numerous other places, and is currently documented in 20 states, 2 Canadian provinces, and Korea. It is hypothesized that much of the spread of the disease can be attributed to the buying, selling, and transporting of deer and elk across the country, and overseas in the case of Korea. In some areas the disease is confined to captive cervids, whereas in other areas, like Maryland, it is found in free-ranging animals.

TSE’s are unique in that they are not caused by bacteria or viruses, but instead by mutated proteins called prions. Prions cause normal proteins found in the neurological system to mutate when they come in contact and these mutations ultimately result in brain tissue damage and eventual death. Prions are extremely difficult to destroy and can persist in the environment for years. Chemical hydrolysis digestion is the most effective way to destroy prions. Research continues on modes of disease transmission, but results to date indicate CWD can be passed among deer via saliva, excrement, and previously infected soil in the environment.

Managing for CWD is not easy. The disease most likely will not cause significant declines in deer populations in the east for the foreseeable future, but it will impact hunter behavior and could actually have the opposite effect on deer numbers. Some states with CWD have shown declines in hunter effort in CWD areas, resulting in decreased annual harvests, which are needed to maintain deer populations. Educating hunters and the public about CWD and maintaining public confidence regarding the disease is critical to effectively managing the disease.

It should be noted that states with CWD that have attempted to eradicate the disease or slow its spread via deer density reductions have had little success. As a result, MD DNR has not employed sharp-shooting or liberalized seasons and bag limits in its CWD management efforts. Baiting and feeding deer was prohibited in the CWD management area, and transport of potentially infected carcass parts out of the area was restricted. Dumpsters were placed in the management area for carcass disposal, and select processors (butcher shops) and taxidermists in the area were identified and educated on proper carcass handling and disposal.

MD DNR will continue to test for CWD annually, concentrating on the current management area. Unfortunately, given the growing infection zone in West Virginia, it is unlikely Maryland will be CWD-free in the near future. While DNR definitely does not want CWD to spread quickly throughout the state, neither does it see the need to significantly impact hunters on a large scale with additional regulations. The best approach at this time is to monitor the presence of the disease in the state, remain up-to-date on developments in CWD research and findings, and continue to educate the public on how to live with CWD.

Additional, up-to-date information concerning CWD can be found at the CWD alliance website and the Maryland DNR website.

For more information about Invasive Species of Concern in Maryland, visit the Maryland Invasive Species Council.

The post Chronic Wasting Disease first appeared on Maryland Invasive Species Council.