Strategy: This biennial, somewhat perennial, invader from Southwest Asia come to the Northwest as an ornamental plant. The parsley/carrot family member looks very similar to a native plant – Cow parsley. The plant can grow to a height of 18 feet and like Poison hemlock, has purple blotches on its stem. It also has very fine hairs that cover the stems and the lower parts of the leaves. The leaves are up to 5 feet long and 2.5 feet wide and very deeply lobed. This invader creates a very large umbrella-like flower cluster that blooms white. The seeds will generally not go far from the plant, but will float in water and can last up to 10 years in the soil.
Attack: Although this plant has not been found in our area it is an Idaho State listed noxious weed. This plant produces a sap of which causes photodermatitis: that is when the sap gets onto the skin and when the sun shines on that skin area blisters are formed. Due to the plants enormous size it shades and covers desirable vegetation, thus becoming the dominate species. This plant requires larger amounts of water thus it will be found along canals, ditches, streams, and ponds.
Defense: Certainly do not plant this future invader. If it is found please notify your County Weed Office. Once found digging up the tuber is effective. Make sure you have water proof gloves under your leather gloves and long sleeve shirts to avoid getting the sap on your skin. There are no biologicals available to control the nasty plant. Literature shows that Roundup is quite effective at a two percent solution. The best control would be Garlon/Vastlan at a 1% solution and sprayed to wet on the leaf surface.
PLEASE NOTE – The proper use and application of herbicides can be an effective way to control and eradicate noxious and invasive plants. Before using herbicides, always carefully follow the label and safety instructions on the label. While we recommend the use of herbicides as one of the effective tools for integrated pest management, the Idaho Weed Awareness Campaign assumes no liability for herbicide applications.