Posted on

three seeded mercury weed

Beyond that is the somewhat labor-intensive, hands and knees on the ground, method of painting the cut stem with a wide spectrum herbicide. Begin with a small bottle of the herbicide and some disposable sponge brushes. Cut each stalk off near the root and quickly, within five minutes before the stalk starts to heal over to protect the roots, paint the cut edge with the herbicide. Be very careful, spilling this could contaminate the soil and kill the other plants, broad-leaf and grasses, and don't spray, for the same reason. This plant is monoecious, which means it has both male and female flowers on each plant, and each plant can carry on creating more plants with no outside help.

The first thing to do is make sure it never has an opportunity to go to seed. Even though it is a perennial that can come up from the roots, it will also propagate itself by the seeds on those tall bracts. This might be a time to break your rule about never mowing; if you mow it before it can seed, and keep mowing it as it sends up more bracts to try to seed again, you might just wear out the food stored in the roots. Doing this for several weeks when the plant is trying to bloom, and thus set seed, could greatly alleviate your problem.


Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Comparisons of King Ranch Bluestem and Kleberg Bluestem grasses
September 03, 2008 – Regarding your answer to a question from Wimberly Tx on November 17 2007 about KR Bluestem: Many people confuse King Ranch Bluestem (Bothriochloa ischaemum) with Kleberg Bluestem (Dichanthium annulatu.
view the full question and answer

Monday – November 09, 2009

Is the mimosa tree poisonous?
September 23, 2008 – Is the mimosa tree poisonous ? If you burn the trimmed limbs is the smoke noxious ?
view the full question and answer

Three seeded mercury weed

Table 2 is based on a summary of 6 field trials in Ontario, 4 conducted by Dr. Peter Sikkema and 2 conducted by Dr. Clarence Swanton.

In the seedling stage this weed is often confused with redroot and green pigweed. It is distinguished from pigweed species by its glossy bronze-green leaf colour, leaf margins with irregular, rounded teeth and clusters of greenish flowers at each axil. In addition Three-seeded mercury has round cotyledons, whereas green and redroot pigweed has very long and slender cotyledons.

Again, products containing the active ingredient atrazine as well as Distinct, PeakPlus and Summit provide effective control of emerged three-seeded mercury (Table 2). Pardner or Koril (applied alone) and Banvel II do not control three-seeded mercury.

Source: Dr. Peter Sikkema and Dr. Clarence Swanton, University of Guelph.

Post-emergent Control in Soybean

Annual, reproducing only by seed.

Source: Dr. Peter Sikkema and Dr. Clarence Swanton, University of Guelph.

Weed Stage: Three-seeded mercury had not emerged at the time of all pre-emergent applications and was at the cotyledon to 8 leaf stage for all post-emergent applications.

Distinguishing Characteristics

Control of three-seeded mercury has been fairly inconsistent with many of the post-emergent herbicides. FirstRate and Classic would appear to be the best option for post-emergent control of this weed.

Table 2 is based on 3 field trials in Ontario conducted by Peter Sikkema.