Tansy Removal

Asked August 11, 2020, 11:49 AM EDT

Hi there! We have a question about the removal of tansy from our pasture. We have a 2 acre pasture where we keep our one horse. This summer it just got overtaken with tansy & we were unable to remove it before now due to a family medical issue. So we are now battling fully grown tansy and trying to figure out the best way to get rid of it. We have already hand pulled a huge trailer load, but much of this tansy is too big or too woody to pull up or the ground is too hard. Should we continue with hand removal (using a weed wacker to cut down at the base and remove the debris by hand) or is it safe to mow with a tractor & leave the debris on the ground to decompose? We don’t want to make our horse sick & we don’t want to hinder the growth of grass that our horse could eat. I’m sending a few pictures for reference. Some of the plants are as tall as my shoulders (I’m 5’4”) and it’s thick! Any advice or help is greatly appreciated! Thank you!

Linn County Oregon

2 Responses

If your horses are in the field, I would encourage you to remove all debris. Using a weed eater, cutting at the base and then removing the plants from the field area would work. If you are able to move your horses to safe pasture area, then mowing and letting the tansy dry and decompose in place would be ok too, but that may take several weeks.

It is likely that tansy ragwort will be a problem for you again next spring. In March, you'll want to scout the field looking for plants in the rosette stage. Spraying with or hand digging are two options in the spring. Please read through this resource and if you have questions, don't hesitate to contact me directly.

Here are two addition free resources that might be helpful to you as well.

Managing Small Acreage Horse Farms: https://catalog.extension.oregonstate.edu/ec1558

Pasture and Grazing Management (online module): https://workspace.oregonstate.edu/course/pasture-and-grazing-management