Knowledgebase
How to eradicate Horse weed from 40% of a yard #876666
Asked July 10, 2024, 12:33 PM EDT
Hennepin County Minnesota
Expert Response
https://www.nrcs.usda.gov/plantmaterials/idpmctn11471.pdf
https://www.extension.purdue.edu/extmedia/gwc/gwc-9-w.pdf
https://www.ag.ndsu.edu/weeds/weed-of-the-year-files/horseweed
Solar starvation is best done under clear plastic. The sun heats up the soil to sterilization levels.
https://extension.okstate.edu/fact-sheets/soil-solarization-for-control-of-soilborne-diseases.html#:~:text=Soil%20solarization%20captures%20the%20radiant,microorganisms%20that%20promote%20plant%20growth.
Thank you for the articles. It is good information.
However, I have a Horse weed infestation in my residence.
Glysophate is not a viable option as it will kill ALL plants and trees.
> it will sicken local animals and birds as well as pets.
Extremely harmful to human contact.
> Given, if it can be eradicated, and to what expense that will take,
> are there any preferred methods of re sodding whereas the horse weed will not affect it again...next season?
If I leave this to be....its only a matter of time before it spreads throughout the neighborhood...then more.
It sounds like lawn service weed control cannot treat it
Thank you for your question regarding the elimination of horseweed. It has been referred to me.
To start, look at the following. It is an excellent description of the plant and its life cycle:
Dealing successfully with horseweed requires a bit of background information about the plant. It is an annual plant having a relatively shallow root structure. It has a single taproot. It can be pulled up rather easily. Its primary way of spreading is via the production of an enormous number of seeds. As you correctly pointed out in your question, this can be over 200,000 seeds per single plant. Wind dispersal is the major way for their distribution. So one control strategy is to pull the plants up prior to their blooming. It seems that you may be dealing with a large area so this tactic may not be realistic.
But what you can do now is to apply a broad-leaf herbicide. This needs to be done ASAP and prior to their blooming. Killing plants after they have released their seeds achieves nothing. Look for an herbicide containing 2,4-D or Dicamba. Read the product label to be sure that it is effective against horseweed. To ensure safety for people and animals, scrupulously follow the application instructions. Herbicide resistance is well documented for horseweed. Usually this resistance is against such things as glyphosate and not herbicides containing the two compounds just mentioned. To cover your bases, use an herbicide that contains both 2,4-D and Dicamba or use two different herbicides containing either one or the other compound. Horseweed can bloom for much of the summer. So a single application of herbicide will not cut it. Plan on doing applications at three different times: now (early July 2024), early August 2024, and then in early September. The overall goal is to kill the plants before they produce and release seeds. Be aware that these herbicides will also kill established plants, both annual and perennial. This can’t be avoided. Try to use direct spraying of these herbicides onto just the horseweed. There is no herbicide that will kill only horseweed and nothing else. See:
https://www.extension.purdue.edu/extmedia/gwc/gwc-9-w.pdf
Some of the seeds produced in 2024 will germinate this fall. Others will germinate spring 2025. To counteract this latter possibility, apply a pre-emergent herbicide in late April to early May 2025. Look for a product containing oxadiazon, dithiopyr, and/or prodiamine. See:
https://www.nurserymag.com/article/glyphosate-resistant-horseweed-control/
I understand your concern regarding the use of glyphosate. I share it as well. Using one or more of the herbicides I’ve described, will be a bit safer. Complete elimination of horseweed will take at least three or four seasons.
Good luck. Please feel free to get back to us if we have not adequately answered your question or if you have additional, related questions. Thanks for using our forum