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Noxious, Invasive and Poisonous Plant Program

The Pennsylvania Department of Agriculture administers the Noxious Weed Control Law and Noxious Weed Control List and implements federal and state eradication and control programs when a noxious weed of limited distribution in the commonwealth is targeted by federal or state funding for suppression, control or eradication.

Poisonous plant identification and information is also provided by the Department and the Department houses and maintains the State Herbarium.  Poisonous Plants of Pennsylvania Publications are available.

Additional information on the twenty Pennsylvania noxious weeds on the control list are available under the publications section of this program. The weeds are listed by their common and scientific names.

Class A Noxious Weeds

Preventing new infestations and eradicating existing infestations of noxious weeds in the class is high priority. The following are Class A noxious weeds:

Giant Hogweed - Heracleum mantegazzianum (Active Field Program)

Goatsrue - Galega officinalis (Active Field Program)

Kudzu - Pueraria lobata 

Palmer amaranth – Amaranthus palmeri

Waterhemp – Amaranthus rudis

Tall waterhemp – Amaranthus tuberculatus

Animated oat – Avena sterilis

Dodder – Cuscuta spp. (Except for native species)

Hydrilla - Hydrilla verticillata 

Broomrape – Orobanche spp. (Except for native species)

Wavyleaf basketgrass – Oplismenus hirtellus

European frogbit – Hydrocharis morsus-ranae

European water chestnut – Trapa natans

Water primrose – Ludwigia grandiflora ssp. hexapetala

Brazilian waterweed – Egeria densa 

Yellow floating heart – Nymphoides peltata 

Class B Noxious Weeds

The department may require control of Class B weeds to contain an injurious infestation, or may provide education or technical consultation. The following are Class B noxious weeds:

Bull thistle or Spear thistle - Cirsium vulgare

Canada Thistle - Cirsium arvense

Musk Thistle or Nodding Thistle - Carduus nutans

Johnson Grass - Sorghum halepense

Mile-a-Minute – Persicaria perfoliata

Multiflora Rose - Rosa multiflora

Purple Loosestrife - Lythrum salicaria

Shattercane - Sorghum bicolor

Poison hemlock – Conium maculatum

Tree-of-heaven- Ailanthus altissima

Parrot feather – Myriophyllum aquaticum 

Wild parsnip – Pastinaca sativa (except for non-wild cultivated varieties) 

Japanese knotweed – Reynoutria japonica (April 8, 2020)*

Giant knotweed – Reynoutria sachalinensis (April 8, 2020)*

Bohemian knotweed – Reynoutria x bohemica (April 8, 2020)*

Class C Noxious Weeds

Preventing introduction and eradication of infestations of noxious weeds in this class is the highest priority.  Class C noxious weeds are any Federal noxious weeds listed on the Federal Noxious Weed List that are not yet established in the Commonwealth and are not referenced above.

Water soldier – Stratiotes aloides 

Controlled Plants

Hemp - Cannabis sativa L and any viable part of that plant with a delta-9 THC concentration of not more than 0.3% on a dry weight basis.

Questions regarding the control programs should be directed to the contact listed below or the nearest PDA Regional Office.

For additional information on invasive species of concern in Pennsylvania, please visit the Pennsylvania Invasive Species Council (PISC).

* Plant has been voted on and approved by the Controlled Plant and Noxious Weed Committee and will become official 60 days after publication in the Pennsylvania bulletin.