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Sagebrush and Yucca Control—Should We?

Sagebrush and Yucca Control�Should We?

by Roger Tacha, Resource Conservationist
Natural Resources Conservation Service
Colby, Kansas

What is sagebrush and yucca control? Is it eradication? Is it thinning?

It could be either, but before doing anything at all, we need to decide whether we should even be worrying about it. Granted, there’s a whole gamut of chemicals that will do the job, possibly in combination with burning or shredding. That is really the simplest part of this issue.

We need to realize that there are many soils on which sagebrush and yucca are supposed to comprise 5, 10, and even 15 percent of the native plant make-up. These soils are generally fragile and subject to erosion by wind and water. The sage and yucca plants are the main plants protecting these soils against erosion processes.

When we pass by or even drive through a pasture with sagebrush or yucca, it is quite normal to think, “Wow, this stuff is thick!” Well, there is a very simple procedure to physically and mathematically calculate how dense it really is�even in some of the thicker stands, the brush canopy usually comes to less than 10 percent. It can be very deceiving!

In these cases, it is usually best to leave it alone, for the following reasons:

  1. After sage or yucca has been eradicated on fragile sites, the grasses present do not all-of-a-sudden replace the voids left by the dead brush. Instead, annual weedy and invasive plants like Russian thistle, grassy sandbur, downy brome (cheat), little barley, and others will quickly germinate and establish. These undesirable plants will take over, and can become solid stands crowding out what desirable species were there with the brush. What a mess!
  2. Now what are we going to do with these annual weeds? They have very limited or no grazing or wildlife value. Are we now going to pick a different chemical and spray them? The cost is escalating!
  3. If we do spray these “nasty replacements,” what then? The remnant desirable grasses still are not going to just rise up and take over. Most likely the weed we just killed will germinate and sprout up again next season or be replaced by other weeds we just listed. Or, maybe nothing leaving only bare ground!
  4. Bare ground? Then we’d have blowouts from wind or gullying from water. Now we are faced with mulching or planting cover crops and re-seeding expensive native grasses that are very hard to establish and very expensive! Now the cost is completely out of hand.
  5. The point should be pretty clear. Was the sage or yucca really a problem in the first place?

There are areas in some fields where the sage or yucca probably is too thick:

  1. Rather than treating the whole field, we ought to be spot treating only these areas.
  2. Additionally, we should consider spot treating in strips�at least this would help hold the soil. Don’t forget�just because we’re now spot-treating or strip-treating, this won’t prevent the weedy pests from coming in. They still will, but they may be more manageable with grazing practices and prescribed fire. The areas would be relatively small, and there would not be severe erosion to contend with.

For more information about sagebrush or yucca control, please contact your local Natural Resources Conservation Service (NRCS) office or conservation district office located at your local county USDA Service Center. To learn more about NRCS, visit the Kansas NRCS Web site at

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