University of Maryland Extension

Invasive Grass Control

 

Bamboo (Phyllostachys and Pseudosasa spp.)

Latin America, the Caribbean, and Asia contribute two types of bamboo: running and clumping. As its name suggests, running bamboo spreads vigorously by rhizomes. Running bamboo should never be planted except with the most stringent, vigilant containment. Used as ornamentals and privacy screens, escaped bamboo has created huge monolithic stands with negligible wildlife value. Be careful not to confuse running bamboo with giant cane (Arundinaria gigantean), which is our native bamboo that grows in Southern Maryland. C&P/S (timing is crucial) - See key below and for further information go to (PDF) HG28 Bamboo

Giant reed (Arundo donax)

Native to India, this perennial grass towers up to 20 feet or more. Once used as an ornamental and for erosion control, it tolerates saltwater where it can displace native wetland plants and obstruct waterways. Spreads by rhizomes and stem pieces transported by water. Digging to control it actually contributes to its spread. C/M/reC, PostE (after flowering) -see key below

Miscanthus/Japanese or Chinese silver grass (Miscanthus sinensis)

Though this ornamental Asian grass has been here for over a century, recent popularity and new cultivars bred for earlier flowering have led to earlier seed maturation and more viable seed spreading on the wind. Clumps widen by rhizome, and thickets arise in disturbed soils, neglected fields, roadsides and other sunny habitats. Natives are out-competed. Its flammability makes miscanthus a fire hazard. It re-sprouts from roots. P/D (young), PostE fall or late spring 0 see key below

Phragmites/common reed (Phragmites australis)

Accidentally imported in ship ballast, European phragmites has spread up and down the East Coast for centuries, displacing millions of acres of wetland plants, including native phragmites. The Maryland Eastern Shore may harbor our only remaining native phragmites. Whereas native phragmites grows in sparse clumps and decomposes readily, European phragmites forms impenetrable monocultures more than 15-feet tall composed of both old and new canes. Subsequently, infested wetlands become dry land, wildlife habitat is destroyed, and a fire hazard created. Roots penetrate several feet deep and extend out 10 feet a season. Wind and water, carrying seed and rhizome/root fragments, have spread phragmites to tidal and nontidal wetland and dry lands, including ditches. It is extremely difficult to combat. Biological controls are being explored. Mowing slows but doesn’t stop it. Burning before flowering stimulates growth, but burning of biomass after cutting benefits reestablishment of natives. Chemical control is the only currently successful method. B, PostE after flowering; C&P/S after flowering - see key below

Wavyleaf basketgrass, (Oplismenus hirtellus ssp. undulatifolius)

This Eurasian grass is a bright green shade perennial, which engulfs forest floor plants in a solid mat. Its widebladed leaves alternate along low-lying stems. Leaves are very unusual with leaf ripples like a flag in the wind. Stems are noticeably hairy (unlike native basketgrass species) and root where nodes touch soil. In fall, seeds with sticky tips attach to passing animals and humans. P/D, PostE - see key below

Key for Control Methods

Mechanical Options

  • (B) Burn: Use controlled fires to destroy aboveground growth. (First, contact local fire department).
  • (C&G) Cut and grind:  Cut down, then grind stump.
  • (C/M/reC) Cut, Mow, and Re-cut:  Cut to the ground and re-cut at the first appearance of new growth.  This starves the root system. It may require persistence.
  • (F/S) Flower/Seed removal Do not allow seed development.  When plant removal must be postponed, prevent spread by seed. Cut off flowers before seed forms. Some plants flower and produce seed at the same time. Bag and dispose of seeds in landfills.  DO NOT compost.
  • (G) Girdle:  Remove bark and cambium layer.  Remove (or spray) any re-sprouting from roots or below girdled area.
  • (P/D) Pull/Dig: This is especially effective with seedlings or annuals. Mile-A-Minute vine, for instance, has almost no root system at all.  However, for those that can re-sprout from a tiny root piece, such as Canada thistle, removal of entire root is critical. Moist soil facilitates.
  • (SM) Smother: Cover plants with cardboard, many layers of newspapers, or plastic, then mulch. Plastic must be removed afterward, and if mulch decomposes on it, this can be an arduous process.
  • (WW) Weed Wrench (TM):  This tool can uproot large shrubs and small trees

Chemical Options

  • (C&P/S) Cut and Paint or Spray:  Cut down trunk and paint or target spray the stump within five minutes.
  • (H/S) Hack & Squirt:  Slash bark using a saw or hatchet, and squirt liquid herbicide into the wounds; re-spray any re-growth. 
  • (PostEPost-emergent herbicides:  Spray foliage of perennial/woody plants. Spot-treat in lawns.
  • (PreE)Pre-emergent herbicide:  Spread this granular herbicide prior to seed germination. 

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