Asked June 15, 2013, 2:12 PM EDT

Is it possible to eradicate the horsetail that is invading our property?

Multnomah County Oregon weed issues

1 Response

Good day, and thank you for using Ask an Expert.

Yes, it is possible to eradicate horsetail but only if you are persistent for the coming 3 to 4 years. Yes, I know that sounds like a drag, but it’s the only method short of moving. Your goal will be to starve the underground roots and potato-like storage structures.

A general strategy:
1. Remove the horsetail at least once every week or two, or as soon as you spot new growth.

2. You may want to move desirable plants out of an infested area then lay black plastic sheeting or landscape fabric over the soil. (See the publications listed below.) It’s said that this may permanently get rid of the horsetail if left in place for three to four seasons. But remain alert! Horsetail has been known to push through landscape fabrics. Then, too, you’ll need to remove occasional “escapes.”
3. If you become weary of your project, and decide to use pesticides:
The only effective chemical available for use by home gardeners is Casoron (active ingredient dichlobenil): Apply in mid-winter. This product will kill herbaceous (green) plants but is safe around established woody plants when used according to label directions.

Pest control companies have access to additional products

Several publications with additional details:
1. “Field Horsetail and Related Species” (Oregon State University; publication # PNW 105) describes the various kinds of horsetail, and the preferred management.

2. “Horsetail Scouring Rush” The weed killers mentioned in this publication are available to, and for use by, professional pest control companies.

Recall that persistence wins. Even so, this project will be your new hobby for a number of years. You must be more determined than horsetail!

Thank you for your inquiry. And good luck.