Frequently Asked Questions

The Strike Team is compiling our most asked questions regarding invasive species and how they affect our ecosystem. Please check back for details, and if you have questions, feel free to use our contact form.

What is an invasive species?
Why do we have invasive species?
What is the cost of control?
What is the impact of invasives species?
Why is this such a problem in the Philadelphia/NJ/NY region?
How are white-tailed deer involved in this problem?
What are some invasive plants? 
What is the difference between “widespread” and “emerging?”
What does the Strike Team do?
What can I do to help?  
How can I remove invasive plants from my property?
How do I choose an herbicide?
What plants/species specifically are invasive species impacting?
How are invasive species different from the natural adaptation/evolution of native species? 
Why aren’t bamboo, vinca or pachysandra on the invasive plant list?
What are the top 5 most threatening plants to forest ecosystems? 
What are some popular landscape plants that I should avoid in my garden?

What is an invasive species?

  • A species that is introduced to an area outside of its natural range that grows densely and excludes other species over large areas.
  • Includes all taxa- plants, birds, insects, pathogens, etc.
  • Invasive species are especially tolerant of human disturbances, are generally free of natural enemies, and produce lots of offspring, which gives them the ability to thrive and spread into new lands.

Why do we have invasive species?

  • Accidental introductions- mile-a-minute vine, insects (packing crates), aquatics (bilge water)
  • Landscaping- Chinese silver grass, wisteria, flowering pear
  • Intentional Introductions - autumn olive planted for erosion control, kudzu planted as forage and erosion control

What is the cost of control?

  • Late 1990’s: Cornell research cites $120-$140 billion a year to US for crop losses, control costs and treating diseases (doesn’t include loss of biodiversity). 

What is the impact of invasives species?

  • Aggressive growth + no natural enemies= large impacts on native species
  • 40-50% of threatened/endangered species are impacted directly by invasive species
  • Invasive plants suppress native plants à native animals are then impacted
  • Invasive insects destroy native plants à native animals are then impacted
  • Invasive mammals, reptiles, fish interrupt the food web
  • Invasives are considered 2nd greatest threat to biodiversity worldwide.  We do not know the full extent of what this means for our planet or human beings.

Why is this such a problem in the Philadelphia/NJ/NY region?

  • Steady flow of new species
  • Intense fragmentation of habitat- creates disturbance and light gaps where invasive species thrive
  • Heavy pressure of white tailed deer on native species that might compete with invasive species

How are white-tailed deer involved in this problem?

  • Deer are native to NJà they prefer to browse native plants
  • Too many deer= to much browsing of native plants and few able to grow to maturity
  • Too much browsing on natives + Little browsing on invasives =invasives taking over

What are some invasive plants? 

  • ~1,000 non-native plants documented in NJ.  Most are considered non-invasive at this point.
  • Emerging (90 species) vs. widespread (30 species)
  • Widespread examples= Garlic mustard, Japanese knotweed, autumn olive, multifora rose, Japanese barberry
  • Emerging examples= Yellow iris, English ivy, Siebold’s viburnum, kudzu, porcelainberry, wisteria, butterfly bush

What is the difference between “widespread” and “emerging?”

  • “Widespread” is common and dense across the majority of the state.  Full eradication is not possible.
  • “Emerging” may be locally common but not common statewide.  Not found often.  Eradication or containment is possible.
  • Strike Team only collects data on emerging invasive species.

What does the Strike Team do?

  • Assist public and private landowners with invasive species identification and eradication.
  • Collect and analyze data on invasive species throughout the state (submit through website, email.  2014 smartphone app in development).
  • Network with local, state, regional and national stakeholders to coordinate education and eradication efforts.
  • Encourage voluntary restrictions on the planting of invasive landscape plants.

What can I do to help?  

  • Understand that plants don’t know boundaries.  They may seemingly behave on your own property while quietly invading a nearby forest.
  • Stop planting invasives.  Remove invasives.  Choose natives.  Educate your nursery.
  • Support ordinances and eventually statewide bans. 
  • Become a Strike Team member!!!

How can I remove invasive plants from my property?

  • Pull or dig and watch area carefully for resprouting.
  • Mulch heavily or cover with weed fabric.
  • Herbicide by either spraying leaves or cutting and treating the stump- contact melissa@njisst.org for specific suggestions.

How do I choose an herbicide?

  • Read the label.  Look for the name of the active ingredient and its percentage.
  • Most herbicides must be mixed with water- read the directions for specific mixing directions.
  • Follow the label for application! 
  • Example- Roundup has an active ingredient “glyphosate” at 53%.  It has a surfactant included in “other ingredients” that is not suitable for use near water.
  • For help interpreting a label, contact melissa@njisst.org for more information on this.

What plants/species specifically are invasive species impacting?

  • Native species!
  • Common shrubs= spicebush, witch-hazel, viburnum
  • Common trees= oak, hickory, maple
  • Insects are very specific feeders and will rarely be able to eat invasive plants.  They are the base of the food chain.  Fewer insects= lower wildlife diversity.

How are invasive species different from the natural adaptation/evolution of native species? 

  • Invasives species are ‘dropped’ into new locations by humans and only partially fit into the ecosystem (e.g., may make fruit eaten by native birds, but have leaves not eaten by native insects).
  • Native species naturally coevolve with each other over time.

Why aren’t bamboo, vinca or pachysandra on the invasive plant list?

  • Bamboo doesn't spread through seed and only slowly spreads by rhizomes into natural areas (unlike Phragmites or knotweed, it doesn't seem to spread by root fragments, so you don't find it 'spontaneously' growing away from plantings).  If it were immediately adjacent to a natural area, it probably should be kept from creeping, but it doesn’t seem to be a major threat -- they seem to stop at the forest edge.
  • Pachysandra and vinca creep a little better than bamboo from plantings in the forest (presumably because they are more shade tolerant), but still not a very serious problem.  They are good indicators of former homesteads.
  • These plants are good examples "invasive in the garden" but not in natural areas.

What are the top 5 most threatening plants to forest ecosystems?  NOTE: These plants were chosen because of their high shade tolerance making shading out by native plants difficult.

  • Siebold’s viburnum, Viburnum sieboldii
  • linden viburnum, Viburnum dilatatum
  • Japanese aralia, Aralia elata
  • Oriental photinia, Photinia villosa
  • Common buckthorn, Rhamnus cathartica

What are some popular landscape plants that I should avoid in my garden?

  • Please consult the Strike Team’s Do NOT Plant list for a full list of all the invasive plants in NJ.  For quick reference, below are 10 of the most common invasive plants used in the landscape. (W=widespread invasive, E=emerging invasive)
  • Callery pear (E)
  • wisteria (E)
  • English ivy (E)
  • Chinese silver grass (E)
  • wintercreeper (E)
  • butterfly bush (E)
  • Japanese maple (E)
  • burning bush (W)
  • Japanese barberry (W)
  • Norway maple (W)