We’ve had a beautiful Spring so far, with so many lovely trees and shrubs still in full bloom. Unfortunately, we also have some vigorous, nasty weeds flourishing in Spring’s wet weather. First, let’s talk about the super-poison one:
All plant parts are extremely poisonous to livestock and human beings, so avoid contact. Plant parts can remain toxic for years.
Brought to US from Europe in 1800's.
Biennial herb grows 8 to 9 feet tall.
White blossoms in late Spring.
Purple blotches on hollow stems.
Especially invasive along stream banks.
One plant can produce 30,000 seeds.
Control by pulling, mowing (wear eye and skin protection) or herbicides (read and follow label directions). Keep out of the reach of children, livestock, pets and wildlife.
This toxic weed could be growing in your backyard!
Remember the old story about Socrates drinking a cup of Poison Hemlock? Deadly stuff to be sure!
This same plant grows wild along roadsides, creeks and wooded areas in Pennsylvania.
Right now – in mid-May – many plants are already 4-feet tall and will bloom soon.
All plant parts are extremely poisonous, especially the seeds, and one plant can produce 30,000 seeds!
Due to the toxicity of Poison Hemlock, bodily contact should be avoided.
Since the plant is a biennial (2 year growth cycle) the best way to control its spread is to eliminate it before it goes to seed.
Herbicides can be used for control in addition to cutting or pulling, but be sure to read and follow label instructions.
Great care should be taken when handling plant parts since they remain poisonous for years after being cut down.
MORE: Additional information on Poison Hemlock from Washington state’s NWCB in this PDF.
Keep out of the reach of children, livestock, pets and wildlife!
Next, we come to a super-invasive weed that’s extremely difficult to eradicate:
This invasive weed could be taking over your backyard!
Species of Knotweed can vary slightly, but they are all bad:
Japanese Knotweed grows up to 6-feet tall with leaves up to 6-inches long.
Giant Knotweed grows to 13-feet tall with leaves up to 12-inches long, with heart-shaped leaf bases.
Bohemian Knotweed is a hybrid of the first two, creating variations of growth characteristics.
IDENTIFICATION: Leaves are alternate (see photos above). Stems are mottled, hollow and have a whitish coating. Knotweed blooms in late summer with creamy-white flowers arranged in spikes along the arching stems.
CONTROL: Extremely difficult to control since the plant grows on a rhizome that stores energy for regrowth if the plant is pulled, cut down or sprayed. Therefore, most methods of control focus on repetitive actions to finally eliminate the plant by weakening and depleting the stored energy in the rhizome, which can take several years. Instead of a “One-Two” punch knock out, you will likely need a “One-Two-Three-Four-Five-Six” to finally get rid of it. Persistence is the key!
The “no spray way” is to repeatedly “cut it low, and let it grow” method, but never letting it grow back to more than 12-inches tall. Therefore, it will need to be cut down every couple weeks, repeatedly, to have any success. Herbicides can be also be used, but check the current recommendations with your state’s agricultural extension office, and always read and follow label instructions.
DISPOSAL: This invasive weed is SO prolific, that it can regrow from a very small piece of root (rhizome) or piece of the stem that includes a node (where a leaf emerges). Therefore, landfill disposal typically calls for wrapping the plants in plastic to prevent regrowth.
MORE: Additional information can be found in this PDF from the Michigan DNR.
Good luck and may the Force be with you! Bob