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
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.