By Andy Valencia
As our summer begins its slow descent into fall, take a moment to relax and enjoy the flowers which nature has provided.
Just kidding! This is Vashon, where Himalayan blackberry will cross your back patio and force its way into your house. You’ll have plenty of time to rest when it’s winter, dark all day, and the world is nothing but mud. Until then, put on your gloves and get to work.
It’s been a while since the reminder went out, so in this issue we’ll talk about a weed that invades fields and gardens aggressively, and is so toxic that Washington state law requires that you control it. This weed is tansy ragwort.
It grows a foot or more tall, with small, cheerful yellow flowers that have a daisy-like petal shape. Does looking at them make you happy? Because although the whole of the plant is toxic, the highest concentration of the pyrrolizidine alkaloids is in the flower. These alkaloids can damage your liver, and can be deadly in higher concentrations.
You are probably not going to munch on tansy yourself, but give a thought to your neighborhood deer. When tansy is fresh, it has a distinctive flavor which deer will avoid. Unfortunately, as it ages and dries, that flavor goes away and deer can eat it unknowingly, with devastating consequences.
Hunters will want to stop and think, since these alkaloids are not removed by cooking, and humans can be exposed by consuming poisoned meat. If a deer looks unhealthy during hunting season, you may want to give it a pass.
If you garden with chemicals, you can look up which available herbicides are effective on tansy ragwort. If you cut off and bag any developing or flowering stems, then spray the base of the plant, you can probably kill it before it develops a new stalk and flowers. Be sure to check back on any previously infested areas, as it often reappears.
Without chemicals, you’ll need a shovel. Dig all around the root ball of the plant, and lever it out of the ground. Shake the dirt loose, then bag and discard the plant with its roots. As with herbicides, it will likely come back and you’ll have to battle it for several seasons before it peters out.
It’s a horrible weed, but the deer and your neighbors will thank you for killing it off. It spreads easily from property to property, and if you let it get far enough out of control, you might even have somebody from King County knocking on your door. Who needs that kind of hassle?
