By June 21, 2013 0 Comments Read More →

Beware of the Giant Hogweed – Report Sightings to APIPP


Giant hogweed (Heracleum mantegazzianum) is widespread in NY, but very limited in its distribution in the Adirondack region. We must remain vigilant in its detection and control to preserve human health. Giant hogweed, native to Eurasia, is a perennial herb in the carrot and parsley (Apiaceae) family with the potential to cause significant dermatitis that “can make a case of poison ivy seem like a mild rash (New York Invasive Species Clearinghouse, 2013).”


Brendan Quirion, APIPP’s Terrestrial Invasive Species Project Coordinator, has been managing several giant hogweed sites in the Adirondacks located in Old Forge, Essex, Westport, and Tupper Lake. The infestations have been treated with a foliar herbicide for several years with the exception of the site in Westport, which was discovered only last year and has been treated only once so far. Giant hogweed tends to grow in colonies, spreading via rootstalk or seeds, and will need to be carefully monitored and managed for several years to come.
Giant hogweed was originally introduced to the U.S. sometime in the 19th Century as an attractive ornamental plant of enormous size. The gardens of Highland Park in the City of Rochester, NY may have been the site of the first North American of giant hogweed. It grows to heights of up to 20 feet with stem diameters of up to four inches with seeds that can remain viable in the soil for up to ten years. Beekeepers once favored giant hogweed for its massive, umbrella-like flower head and the substantial amount of food it could supply to honey bees. Seeds are also commonly dried and ground into a spice in Iranian cooking recipes. Unfortunately, the environmental risks and potential human harm caused by this plant and its sap far outweigh any benefits.
When sap from giant hogweed or any of its parts (including seeds and roots) comes in contact with human skin – reportedly moist or perspiring human skin – it reacts with sunlight resulting in painful, blistering, burn-like sores. These sores may leave purplish-black scars that can remain photosensitive for years after the initial irritation. The irritation begins with skin redness. Within the first day of exposure, burns or lesions begin to form, followed by large blisters that occur within 48 hours. These initial symptoms usually subside within a few days.
The only known cure or antidote for giant hogweed’s phototoxic skin effects is to immediately attempt to wash the sap off of the skin with soap and water before the reaction occurs. If a reaction does occur, medical advice should be sought.
Anecdotally, there have been incidents of giant hogweed affecting white-faced sheep and pale skinned livestock. It is also important for farmers to take precautions when handling their animals if the potential for giant hogweed contact exists because the sap can be transferred from animals to humans. Landscapers, yard laborers, and small children that are prone to play with or among the curious-looking plant are at a higher risk of exposure to giant hogweed’s harmful effects.
Giant hogweed common lookalikes
 For more information, please visit The New York Invasive Species Clearinghouse.

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