Tansy Ragwort is the poster child of noxious(poisonous) invasive weeds. A quick Google search will show you pictures and all you need to know. It has made a lot of progress invading the island. One feature that sets it apart from other innocent little yellow flowers is the way the stalk goes red at the base, and when you grab it, it emits a sour odor Like geranium.  Other plants retreat as that odor is in the roots and it poisons the ground. This time of year, horses have pretty much eaten everything in their pasture but a 3’ tall yellow flower. They know not to eat it. But if the seeds blow into a hayfield and the plant gets mowed into the hay, it causes liver failure. The crop is ruined for years. It is along the highway because the seeds blow with the wind of the cars. And county mowers will distribute seeds. If pulled plants are sealed in a plastic bag, the transfer station will take them for free. The plants make bees aggressive. So if bees are on them, comeback later. I hate to think that pollen is in our island honey!  Our good citizens are helping one another out controlling this plant. Wear gloves if you decide to take up the cause.

Ok to cut the flowers off?
I am glad you asked that. Just like carrots, the plant grows in a two year cycle. The first year it puts out quite recognizable greens and establishes it's roots. The second year it blooms. Yes, if you take the flowers, it stops the seeds from being broadcast. And the plant will die. However the toxins in the roots remain in the soil, holding space for it's progeny. Look around the bloomer. You will likely see some juveniles poised to take their place next year. Get them out by the roots too. All this effort will be a perennial problem, even if we are thorough and consistent, it can take several years to eradicate, as the seeds can endure a long time in the environment. Just like Covid-19. One big house-party of a weed patch can re-infect the whole region, especially disturbed soils where trees are cut, or soil is plowed for organic growing.

It blooms in the time of year that fire hazard is greatest. So these days, the transfer station will take sealed bags of it for free. I fill the bags, seal them and let them swelter in the sun. When I have enough to fill the truck, we make the trek to Coupeville. I make sure the bags are well sealed so I don't contaminate my own yard with the seeds.  Bayview recycle also takes the bags.  (article from the Seattle Times)