Partner Announcement
August 25th: Lincoln Soil & Water Conservation District turns 70!
Thank you to our community and partners who have supported us over these many years- we take pride in our service to the county and are eager to continue our work for many more years to come.
The Weed Wire: Poison Hemlock
History and Native Range: Conium maculatum is a highly toxic plant originating from Europe and the Mediterranean, including northern Africa. Despite its deadly toxicity, it is believed that poison hemlock was first introduced to North America as an ornamental garden plant in the 1800s. It has also become a widespread invasive in Asia, New Zealand, and Australia. Throughout both its native and introduced ranges, it is found in areas of disturbed soil such as roadsides, ditches, and cultivated field edges. It prefers wet and poorly drained environments but can establish in dry areas as well.
Identification: Poison hemlock has several other lookalike species in the Oregon Coast region, however none of which are sensitive native species. These lookalikes include Queen Anne’s lace (Daucus carota- non-native, non-toxic); cow parsnip (Heracleum maximum- native, not deadly but sap can cause skin rashes); giant hogweed (Heracleum mantegazzianum- non-native, same toxicity as H. maximum); and water hemlock (Cicuta douglasii.- native, but similarly deadly poisonous as C. maculatum).
Poison hemlock can be distinguished from Heracleum spp. and Queen Anne’s lace by the fact these three lookalikes all have hairs on the leaves and stems, while poison hemlock has smooth leaves and stems. Poison hemlock can also be distinguished from the similarly hairless native hemlock by their leaves, with the invasive hemlock having lacier leaves.
(Native hemlock on left; invasive hemlock on right. Photo credit: Steve Dewey, Utah State University, Bugwood.org)
The Problem Here: Poison hemlock, being a versatile plant capable of growing in a range of disturbed or degraded habitats, can spread quickly and take over large swaths of ground whilst displacing native species, much like any other invasive plant does. It is the deadly toxicity of this plant in combination with its aggressive growth habit that makes poison hemlock a notable concern.
The toxic and invasive nature of poison hemlock can lead to sickness or death for livestock, elk, and deer. Grazing animals will avoid poison hemlock when possible, but accidental ingestion becomes more likely as the plant becomes more prevalent. Poison hemlock also remains deadly toxic for up to three years after being dried, and can contaminate hay, which is a more common route of livestock poisoning. Human ingestion- accidental or by misidentification- can also be easily fatal.
Manual Control: Digging or hand-pulling poison hemlock can be effective for small infestations, while mowing or deadheading larger patches before the plant goes to seed can prevent infestations from spreading. Care should be taken when practicing manual control; gloves and long sleeves are recommended to avoid skin exposure to the sap, which can cause irritation. Plant compounds aerosolized by mowing can also cause irritation; consider wearing a mask or respirator when mowing large patches.
Do NOT treat poison hemlock by burning, as the smoke will also contain deadly compounds.
Herbicides: When used according to label directions, herbicides can be a safe and effective way to control poison hemlock. Glyphosate or triclopyr are particularly effective and best used in late spring or early summer. Chemical treatment of seedlings and small rosettes is more effective than treatment of mature plants; repeated treatments may be necessary until the seed bank is depleted. As poison hemlock frequently grows near surface water, aquatically formulated herbicide products are recommended.
Links to Information and Studies:
Upcoming Events
Conservation Kayak Series Alsea Edition
Join The District and our group facilitators as we kayak the Salmon River!
September 3rd, 10 AM to 2 PM the District and partners will be kayaking the Salmon River. We will be launching from the ODFW Fish Hatchery and taking out at Knight Park near the mouth. Please RSVP at info@lincolnswcd.org if you would like to attend!
We will be discussing noxious weeds impacts and riparian restoration efforts in the area with the Nature Resource Conservation Service, Water Resources Department, MidCoast Watersheds Council, and Lincoln SWCD.
Be prepared to be in the elements for several hours. Please bring enough food, water, sunscreen, and other supplies you will need for the day. Light snacks will be provided. Keep an eye out for announcements on further installments for this series!
Partner Spotlight
MidCoast Watersheds Council
