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 How To Control Giant Hogweed 
 
 The information on this page is available in a more extensive PDF format. View complete Giant hogweed Control Methods (PDF, 500 KB) document. 
 
 Giant hogweed can be controlled manually, mechanically, and with herbicides. In some cases, a giant hogweed infestation is best controlled using several different methods in combination or in succession - in other words, a two, three, or even four-pronged attack plan. The final part to any control method is to plant grasses or other vegetation to provide competition for giant hogweed and decrease soil erosion. 
 
 In order for your control effort to be successful, you will have to ensure that no additional seeds are being introduced to the area. With no influx of seed and a few years of persistent control efforts, giant hogweed plants can be eradicated. 
 
 Before beginning or performing giant hogweed control, be sure to carefully read and follow the Health Hazards & Safety Instructions (this page contains graphic photos)! 
 
 Overall Giant Hogweed Control 
 
 Prevent introduction into new areas Do not move soil contaminated with seed. If removal of contaminated soil is necessary, seedling emergence can be prevented by burying the soil to a minimum depth of 20 inches (50 cm) and covering it with clean soil Sowing and planting giant hogweed is PROHIBITED Since the dispersal of giant hogweed is almost entirely by seeds, it is very important to prevent the plant from setting seed Control new, smaller infestations first before the seed bank has a chance to establish 
 
 
 
 Field technician root-cutting hogweed plants. Field technician root-cutting hogweed plants. 
 
 Manual & Mechanical Control 
 
 Methods include root cutting, flower head/seed head removal, cutting and mowing, and cut and cover. Except for root cutting, manual control will not cause immediate death of the plant. All other methods will need two to three treatments per year for several years to deplete the root reserves and kill the plants. All methods will need to occur for multiple years until no new plants grow from the seed bank. Monitor the site for at least three more years to make sure no new seedlings appear. 
 
 a. Root cutting 
 
 This method is ideal for a single plant or small infestations. We have found 400 plants to be a manageable amount for two people to control manually. 
 
 Cut the taproot approximately six inches below ground level using a spade, shovel, or anything with a large sharp edge. In areas with erosion or on steep inclines (where additional soil may be covering the plant base), plants may need to be cut up to ten inches below the soil. 
 
 
 
 If possible (for your safety), cut the plants before the leaves are very large. 
 
 The cut part of the plants should be removed from the soil and left out to dry (safest for control person) or bagged and disposed of. 
 
 If the plants do not die, cut them again when they regrow. 
 
 When using the root-cutting method, another attack strategy is to apply herbicide to the cut root remaining in the soil to help ensure no part of the root grows back the following year. 
 
 b. Hogweed flower head/seed head removal & safe disposal 
 
 Cut off the flower heads after the seeds have formed but before they mature. This will prevent the plants from shedding the seeds and from forming new flowers on lower branches. 
 
 
 
 Clear trash bags are the best for solarization (a method of using the heat from the sun to destroy the seed viability) but dark bags are suitable as well. 
 
 Seal trash bags tightly. 
 
 If sap has gotten on the outside of the bag, put it inside another trash bag so the outside is safe to handle. 
 
 Place in a secure location where they will be exposed to direct sunlight to give flowers and seeds solarization for at least two weeks. 
 
 Dispose of trash bags in the garbage. 
 
 c. Cutting & mowing 
 
 Start when plants are small and continue mowing throughout season. DO NOT mow if the plants are larger than your mower and NEVER mow if there is a flower or seed head. 
 
 If you choose to use this method, the plants must be cut at least three times during a growing season for several years. 
 
 Repeated mowing is often used for large infested areas and if done consistently and on a regular basis can destroy most of the plants. 
 
 Be careful not to spread the seeds - all flower heads should be removed and carefully disposed of prior to mowing. 
 
 Mowing equipment should be cleaned before using in another area to avoid spreading hogweed seeds. 
 
 d. Cut & cover 
 
 Cut the plants down to ground level and cover the soil with black plastic or landscape fabric with mulch on top. 
 
 Check the following year to make sure seedlings do not poke through. 
 
 After a few years, remove the plastic and re-vegetate the area. 
 
 Herbicide Control 
 
 Giant hogweed is susceptible to systemic herbicides, such as glyphosate and triclopyr. The application of these herbicides is considered effective and cost efficient and can be used for the control of a single plant or large stands of giant hogweed. These systemic herbicides will be absorbed by the leaves and will move into the root to prevent regrowth the following year. Triclopyr is a selective herbicide that acts only on broadleaf plants and will not harm grasses in the area. Glyphosate is non persistent in the soil but is also a non-selective herbicide and will kill any surrounding vegetation it comes in contact with. Some triclopyr and glyphosate products (example: Rodeo) are labeled for use in riparian areas and near water. Areas sprayed with triclopyr can recolonize with grasses and other herbaceous species within the same growing season which helps to suppress giant hogweed seedling growth and decrease soil erosion. Recolonization at sites using glyphosate will probably be slower than sites using triclopyr unless re-seeded. 
 
 Spray giant hogweed leaves with an herbicide containing triclopyr or glyphosate as the active ingredient. Use the recommended manufacturer's dose and follow label instructions - there is no advantage to using a higher dose. Apply the herbicide between March and early June when hogweed leaves are green and actively growing. A follow-up treatment, in July or August, may be needed for the plants that did not die from the first herbicide application. During this follow-up treatment it is strongly recommended to remove any flower heads present to decrease next year's seed source. It is easiest to spray before the plants grow overly tall. Giant hogweed plants can be sprayed later in the season as long as they are still green and not dying back. Another option is to carefully cut the plants above waist height and spray below. To be successful in eradicating giant hogweed, herbicide treatments (or another control method) will have to be repeated for a few years, in order to kill the plants missed the prior year as well as the plants emerging from the seed bank. 
 
 Spray during dry and calm weather. Cover leaf surfaces thoroughly with spray droplets, but do not spray to the point that liquid is dripping off the leaves. Do not apply herbicide to non-target organisms as you want the other plants to live and revegetate the area. It may take plants treated up to one week or more depending on moisture levels before symptoms appear. Do not cut or dig the plant until the top growth has died back. If the leaves remain green several weeks or a month after the initial treatment, spray them with herbicide again. 
 
 For Licensed Pesticide Applicators 
 
 There are five herbicides that are legal for specific use on giant hogweed due to FIFRA 2(ee) Recommendations: 
 
 Accord XRT II, EPA Reg. No. 62719-556 
 
 Garlon 4 Ultra, EPA Reg. No. 62719-527 
 
 Rodeo, EPA Reg. No. 62719-324 
 
 Roundup ProMax Herbicide, EPA Reg. No. 524-579 
 
 Roundup Pro Concentrate Herbicide, EPA Reg. No. 524-529 
 
 Some of these herbicides are classified as restricted and can only be applied by, or under the supervision of, a certified commercial pesticide applicator. A copy of the FIFRA 2(ee) Recommendation letter as well as a copy of the herbicide label needs to be carried by the applicator when applying herbicides. The 2(ee) recommendations can be downloaded at the NYS Pesticide Product, Ingredient and Manufacturer System (PIMS) database web site (leaves DEC website). 
 
 It may be possible for hogweed seeds to remain viable in the soil for 15 years. For this reason, long-term monitoring is very important. Check the site and surrounding areas for the next several years for the emergence of any hogweed seedlings or regrowth from previous year's plants. 
 
 This step is crucial! After removing giant hogweed plants, you may be left with an area of bare soil vulnerable to soil erosion, giant hogweed seedlings, and introduction of other invasive weeds. Re-establishment of native or non-invasive vegetation (e.g. through sowing grass mixtures) at treated sites may be necessary to help achieve your desired control outcome. This will help to reduce soil erosion and provide competition for giant hogweed seedlings. 
 
 For more information about control of giant hogweed, please see The Best Management Practice Manual (PDF, 2.5 MB). This manual was developed by numerous experts in Europe to control this invasive plant. 
 
 
 
 ||||| Officials in Virginia are warning residents to be on the lookout after an invasive plant was found Tuesday in the northern part of the state that can cause third-degree burns and even permanent blindness. 
 
 The Massey Herbarium at Virginia Tech said in a Facebook post that 30 giant hogweed plants were discovered in Clarke County, located between Winchester and Leesburg. 
 
 The plant contains a very toxic sap, that when combined with sun exposure, can cause severe health hazards. 
 
 "In brief, the sap prevents your skin from protecting itself from sunlight, which leads to a very bad sunburn," according to the New York Department of Environmental Conservation. "Heat and moisture (sweat or dew) can worsen the skin reaction. The phototoxic reaction can begin as soon as 15 minutes after contact, with sensitivity peak between 30 minutes and two hours after contact." 
 
 The sap can cause painful blisters that can form and become "dark and pigmented," and scars that can last up to six years, according to the NYDEC. 
 
 WARNING: GRAPHIC PHOTOS BELOW 
 
 If the sap gets into the eye, it can even lead to blindness. 
 
 Environmental officials in Virginia said that while there has just been one confirmed case in Clarke County, they are warning residents in other parts of the state to stay alert for potential sightings. 
 
 "There have been reports from VDOT of sightings of Giant Hogweed in the Staunton area and Middlesex County," Isle of Wight County posted to Facebook. "There is a strong possibility that the Giant Hogweed could find its way into the Tidewater/Coastal Virginia area." 
 
 Besides being a threat to humans, giant hogweed can also impact the environment. The plant can grow up to up to 14 feet, creating a lot of shade in the area and inhibiting the growth of native species. The plants have hollow stems that are generally 2 to 4 inches in diameter, with dark purple and red raised spots and bristle-like hairs. 
 
 Environmental officials say that if you want to remove the plant, do not use a weed-whacker, because the plant's sap can splatter and then spread quickly. Eradication should be done by physical removal or using herbicides such as glyphosate or triclopyr, according to the NYDEC. 
 
 "It may be possible for hogweed seeds to remain viable in the soil for 15 years," the agency said. "For this reason, long-term monitoring is very important. Check the site and surrounding areas for the next several years for the emergence of any hogweed seedlings or regrowth from previous year's plants." ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| See more of VT Massey Herbarium on Facebook ||||| Tweet with a location 
 
 You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more ||||| If Hollywood wanted to make a movie about a horrifying plant invasion, giant hogweeds would make a great candidate for the lead role - they are absolutely massive, incredibly toxic, and readily spread wherever their seeds take root. 
 
 Listed as a noxious weed in at least eight states, last week the giant hogweed (Heracleum mantegazzianum) was spotted in Virginia for the first time. 
 
 According to reports from the Massey Herbarium at Virginia Tech university, about 30 of these towering plants have been found in Clarke County, and locals are warned to keep an eye out for sightings. 
 
 Today I helped ID VA's first giant hogweed population! Its sap causes severe burns. One plant was found in Clarke County. Report sightings to your extension agent! ID help: https://t.co/VMkYqyaccB Thanks to @herbariumkeeper and @VTAgWeeds for ID help and report! pic.twitter.com/4BM9RhyMem — VT Massey Herbarium (@MasseyHerbarium) June 12, 2018 
 
 Native to the Caucasus region, the statuesque plant looks like a huge mutant version of the benign common hogweed - but it can cause severe skin burns if you so much as brush against the bristles on its stalks. 
 
 Those bristles, along with the rest of the plant, emit a nasty sap that chemically irritates the skin causing phototoxicity - severe damage to the skin through exposure to sunlight and UV rays. 
 
 As a result, one can get huge, oozing blisters that can leave behind scars and photosensitivity for many years (you can see some NSFW photos of giant hogweed-caused blisters here.) 
 
 But unless you're familiar with its nasty secret, you might think the giant hogweed looks cool - these large plants can grow more than 4 metres (14 feet) tall, spreading their huge leaves and producing massive umbrella-shaped clusters of white flowers. 
 
 After Britain first made the mistake in the 19th century, as an "ornamental" garden plant it was also introduced to North America just a few decades later, and since then it's been a battle to stop the flowering monster's march across the continent. 
 
 Hogweed warning sign in Ontario, Canada (Gavin Edmonstone/Flickr/CC BY-NC 2.0) 
 
 Once you have an infestation, it takes a lot of work to control the giant hogweed to prevent its spread, as its seeds - each plant can shed thousands - remain viable in the soil for several years. 
 
 "In some cases, a giant hogweed infestation is best controlled using several different methods in combination or in succession - in other words, a two, three, or even four-pronged attack plan," explains the New York Department of Environmental Conservation (NYDEC). 
 
 Those methods involve cutting the plant roots, removing seed heads, mowing them down when they're still small, and even dosing the whole thing with herbicide. Of course, going anywhere near a giant hogweed requires protective gear. 
 
 Weirdly enough, H. mantegazzianum isn't even the only horror weed that's come to plague the world from its Caucasus origins. 
 
 The closely related H. sosnowskyi species, discovered in Georgia in the 1930s, was brought into the Soviet Union for growing as cattle feed. These days, it is by far the scariest plant you could find in the Baltic States and Poland, where it's considered highly invasive. 
 
 It's easy to imagine that one day far in the future, when humans are all dead, whole swathes of our planet could be overgrown with this incredibly toxic, fast-growing plant. Movie writers, you're welcome. 
 
 To learn about the identification of giant hogweed and compare it to common look-alikes, check out the NYDEC site here. ||||| Skip to main navigation 
 
 Health Hazards & Safety Instructions for Giant Hogweed (with graphic photos) 
 
 When giant hogweed (GH) sap, which contains photosensitizing furanocoumarins, contacts human skin in conjunction with sunlight, it can cause phytophotodermatitis - a serious skin inflammation. In brief, the sap prevents your skin from protecting itself from sunlight which leads to a very bad sunburn. Heat and moisture (sweat or dew) can worsen the skin reaction. The phototoxic reaction can begin as soon as 15 minutes after contact, with sensitivity peak between 30 minutes and two hours after contact. 
 
 Photo of giant hogweed burn - 5 days to 5 months after initial exposure Photo credit: Bob Kleinberg 
 
 What are the symptoms of exposure to giant hogweed sap? 
 
 Painful blisters that form within 48 hours and become dark and pigmented 
 
 Scars that last up to six years, though typically only last a few months 
 
 Long-term sensitivity to sunlight is common 
 
 Blindness may occur if the sap gets into the eye 
 
 Where is the toxic sap located? 
 
 Sap can be located in all parts of the plant but the following have higher concentrations: the lower part of the hollow stems and petioles; the hollow hairs on the plant; the foliage, stem, flower, or fruit (seed). 
 
 Safety precautions to follow when controlling giant hogweed plants: 
 
 Refer to the How to Control GH webpage which includes a detailed guide 
 
 Do not touch the plant with bare skin 
 
 Do not touch your bare skin with sap covered gloves 
 
 Prevent UV sunlight from reaching skin by: 
 
 wearing long waterproof gloves, long sleeves, pants, boots, and eye protection; synthetic water-resistant materials are best since cotton and linen fibers can soak up the plant sap and be penetrated by plant hairs If controlling plants with multiple people, keep a good distance from one another as the sap can splash three to four feet Apply sun block before beginning to work 
 
 Launder clothes that may have contacted plants 
 
 Wash equipment with water immediately after use 
 
 Limit exposure to sunlight after control OR work around giant hogweed plants after sunset 
 
 DO NOT use a "weed-whacker" or brush cutter - sap may splatter as stems are cut 
 
 Keep water, soap, and eye-wash near work area in case of exposure 
 
 What should you do if you are exposed to giant hogweed sap? 
 
 Wash the affected area thoroughly with soap and COLD water as soon as possible 
 
 Keep exposed area away from sunlight for 48 hours 
 
 If a reaction occurs, topical steroids applied early can reduce the severity of the reaction and ease discomfort 
 
 If sap goes in eyes, rinse them with water and wear sunglasses 
 
 If a reaction has occurred, the area of skin may be sensitive to sunlight for a few years and you may want to apply sun block or keep the affected area covered from the sun when possible 
 
 See a physician if you have a reaction or any questions 
 
 
 

– What ScienceAlert calls a "giant horror plant" has made its way to yet another US state, and people who come in contact with it could feel the pain. Virginia Tech's Massey Herbarium tweeted last week it had IDed a giant hogweed (aka Heracleum mantegazzianum) plant in Clarke County, later updating that count on Facebook to 30 plants. The plant holds what Fox News deems a "toxic sap," which prevents human skin from protecting itself from the sun's rays, leading to severe burns that can be worsened by sweat. New York state's Department of Environmental Conservation lists other hazards that can result from coming in contact with the plant (as well as some photos of terrible burns), including long-term sunlight sensitivity, oozing blisters, scarring, and even permanent blindness if the sap makes its way into one's eyes. And it doesn't take a lot to fall prey to the poison of the giant hogweed, which resembles an umbrella or mushroom made up of white flowers: A simple brush up against its bristles can spur a reaction as soon as 15 minutes later, with "sensitivity peak between 30 minutes and two hours after contact," per the DEC. It's difficult to stop the spreading of the invasive plant, which is native to the Caucasus region near Russia and was introduced to the US sometime in the early 20th century. Virginia environmental officials are warning the plant may have been spotted in other parts of the state and for people who come across it to not let their bare skin make contact. It also offers a guide for very carefully getting rid of the plant. (Giant hogweed has been found in at least a dozen other states.)