Invasive Species Alert

English Ivy (Hedera helix)

Native to Europe, western Asia, and North Africa, English Ivy is an evergreen woody vine that easily climbs and forms dense ground cover in forests. It infests woodlands, fields, hedgerows, and other land areas, crowding out native vegetation. As it climbs trees, English Ivy engulfs and kills branches by blocking light from reaching the tree's leaves. The host tree eventually will succumb to the steady weakening from prolonged loss of sunlight. 

english_ivy_main

English Ivy can also cause damage to manmade structures, pushing into cracks and fissures in any spaces between rocks, bricks, siding, shingles, etc. The vines can also serve as "highways" for insects and other pests. 

Removing English Ivy

Manual, mechanical, and chemical control methods are all effective in removing and killing English Ivy. Loudoun County Master Gardeners has these tips for safely removing English Ivy from trees and structures: 

If you like the appearance of vines in your garden consider alternative native species, such as Cross Vine (Bignonia capreolata) or Carolina Jessamine (Gelsemium sempervirens)

Wavyleaf Grass (Oplismenus hirtellus)

First discovered in Baltimore County in 1996, Wavyleaf Grass has spread rapidly throughout Maryland and into Virginia over the past two decades. Wavyleaf grows low to the ground and spreads easily across the forest floor displacing native plant species completely. Due to the Wavyleaf's sticky, spikelet seed, the invasive grass is often spread unintentionally by clinging to both humans (i.e. hikers) and animals alike. 
wavyleaf

Removing Wavyleaf Grass

Very small patches of Wavyleaf Grass can be controlled by hand pulling before roots take hold. It can also be controlled by clethodim herbicides, which is grass specific. Several years of control are often required to deplete mature Wavyleaf Grass. Hikers should take special care to remove all seeds that stick to clothing, shoes, and pets prior to leaving the forest.

If you like the appearance of Wavyleaf Grass, consider native alternatives like Deer-tongue grass (Dichanthelium clandestinum) or Bottlebrush Grass (Elymus hystrix).

Tree of Heaven (Ailanthus altissima)

Brought to North America from China in the 18th Century, the Tree of Heaven is also known as stinking sumac (due to its flowers' unpleasant smell), Chinese sumac, and varnish tree. The Tree of Heaven reproduces very quickly, aggressively crowds out native species, and secretes a chemical into the soil that is toxic to surrounding plants.
Tree of Heaven

In addition to harming the native ecosystem, the Tree of Heaven can also cause damage to pavement, sewers, and building foundations due to its aggressive root system. It also has helped advance the spread of the invasive spotted lanternfly (see below).

Removing Tree of Heaven

The most effective way to control Tree of Heaven is to pull seedlings by hand before the root takes hold. Mature Tree of Heaven plants are harder to successfully remove, as the entire root must be removed since broken fragments may resprout. Penn State Ag Extension provides a comprehensive method and best timing for removing Tree of Heaven plants.

If you like the appearance of Tree of Heaven plants, consider native alternatives like the Pignut Hickory (Carya glabra) or Smooth Sumac (Rhus glabra).

​Spotted Lanternfly

The spotted lanternfly (SLF) was detected in Virginia in January 2018. It is an invasive planthopper that was discovered in Pennsylvania in 2014. In Pennsylvania and its native range, SLF is a pest of grapes, peaches, hops, and apples. It is commonly associated with tree-of-heaven, Ailanthus altissima. It has the potential to be a serious pest of agriculture and home gardens in Virginia.

spotted-lanternfly


​Signs of Infestation

Signs and symptoms of the spotted lanterfly include:
  • muddy-grey egg masses on or around host trees until eggs hatch in late spring; 
  • dark streaks or sap flowing down the bark of the tree resulting from the spotted lanternfly piercing the bark to access phloem and sap in order to feed;
  • honeydew secretions (insect secretions) at the base of a host tree that can become covered in a sooty-coloured mold; and,  
  • increased bee and wasp activity due to exposed sap and honeydew adult insects congregating on host trees (especially Ailanthus altissima) in the fall.

Do you think you’ve identified a spotted lanternfly?

If you think that you have found a spotted lanternfly, you can take a specimen to your local Virginia Cooperative Extension office (https://ext.vt.edu/offices.html).



To learn how to identify spotted lanternfly, visit Virginia Cooperative Extension’s Spotted Lanternfly page: ext.vt.edu/spotted-lanternfly.


Emerald Ash Borer


An infestation of this non-native beetle was confirmed in 2015 in neighboring Fairfax County. The Emerald Ash Borer was first discovered killing ash trees in Michigan in the late 1990s.

Accidentally introduced into North America from Asia, the Emerald Ash Borer has killed tens of millions of ash trees and caused billions of dollars of damage to the forestry industry. This is only the second time that this pest has been found in the Northern Virginia area since a minor outbreak was contained in 2003.
Emerald Ash Borer

Types of Ash Trees


There are many species of ash trees and the emerald ash borer will attack them all; the result is almost always fatal. Green and White Ash trees are commonly found in this area. Please visit the Dendrology at Virginia Tech Web site for more information on how to identify ash trees.

Signs of Infestation


Early detection is the best strategy for management of the pest. Signs of emerald ash borer activity include dieback in the top 3rd of the tree canopy, sprouts growing from roots and trunk, bark splitting and D-shaped exit holes. To learn more about emerald ash borer please visit the United States Department of Agriculture (USDA) Forest Service website.

The emerald ash borer does not generally spread great distances on its own. It is mainly spread when various ash articles (firewood, wood chips, nursery stock, etc.) are transported from infested areas to uninfected areas.

Citizen Reports


Residents are asked to report any signs of declining or dying ash trees by contacting the Department of Public Works at 703-248-5350 (TTY 711) or dpw@fallschurchva.gov.
Healthy Ash Tree
Ash Trunk Growth
Canopy Dieback