Braken Fern in pasture - Ask Extension
I just fenced in a new sheet pasture and now I'm seeing a section of brackenf ern coming up. What is the most thorough and safest way to manage this p...
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Braken Fern in pasture #928232
Asked April 13, 2026, 11:48 AM EDT
I just fenced in a new sheet pasture and now I'm seeing a section of brackenf ern coming up. What is the most thorough and safest way to manage this plant in my sheep pasture? It was suggested that I do some research on type of herbicides to use on this particular plant and two fence the sheep out of that area as some herbicides increase their interest in the plant. Also, will sheep naturally avoid this plant?
Clackamas County Oregon
Expert Response
Hello,
How big is your patch of bracken fern?
Typically, grazing animals will avoid toxic plants on their own unless no other forage is available. We see most cases of toxicity in overgrazed pastures. However, toxic and noxious weeds should be managed so that they don't get bigger over time.
You can manage bracken fern over time by repeatedly cutting the fronds or using an herbicide. Any time you cut toxic weeds, you need to remove the material from the pasture, as toxic plants wilt and dry, they become more palatable to livestock. Similarly, when they are sprayed with an herbicide, they wilt and can become more palatable.
A list of herbicides labeled for bracken fern can be found in the PNW Weed Management Handbook. You can view the link for the recommended rate and other important information. Always apply exactly as the label on the product states. Glyphosate can be applied when the fronds are at least 18 inches long; they recommend dicamba in the late winter. Note that asulam is only allowed on uncultivated land, reforestation sites, and Christmas tree plantations (not pastures).
From a Utah State Article:
"Timing is important in any treatment of bracken fern. The most effective time for treatment is summer just after the new fronds have fully expanded and starch reserves in the rhizome are at their lowest level. Two or more annual treatments and combinations of cutting and herbicide are more effective than single treatments or even single annual treatments.
Mechanical Treatment: Cutting early in the summer, allowing the rhizomes to regenerate a second crop of fronds, then recutting will deplete the resources of the rhizome much faster than a single cutting. However, single, annual cuttings or deep plowing can be effective during midsummer."
Utah State Bracken Fern Article
You can choose between repeatedly cutting or applying herbicide. If you go the herbicide route, I would apply it to fronds of at least 18 inches, following the label on the product exactly. I would keep the sheep out until the plant had completely died and make sure there aren't any dried fronds left. Either way, marking the area with flags or by placing a pin on an electronic map so I could recheck the area and control as needed. It will take a while to control; consistency over a few years is key!
You can reach out to me directly if you have any follow-up questions.
Sincerely,
Hayley White
<personal data hidden>
How big is your patch of bracken fern?
Typically, grazing animals will avoid toxic plants on their own unless no other forage is available. We see most cases of toxicity in overgrazed pastures. However, toxic and noxious weeds should be managed so that they don't get bigger over time.
You can manage bracken fern over time by repeatedly cutting the fronds or using an herbicide. Any time you cut toxic weeds, you need to remove the material from the pasture, as toxic plants wilt and dry, they become more palatable to livestock. Similarly, when they are sprayed with an herbicide, they wilt and can become more palatable.
A list of herbicides labeled for bracken fern can be found in the PNW Weed Management Handbook. You can view the link for the recommended rate and other important information. Always apply exactly as the label on the product states. Glyphosate can be applied when the fronds are at least 18 inches long; they recommend dicamba in the late winter. Note that asulam is only allowed on uncultivated land, reforestation sites, and Christmas tree plantations (not pastures).
From a Utah State Article:
"Timing is important in any treatment of bracken fern. The most effective time for treatment is summer just after the new fronds have fully expanded and starch reserves in the rhizome are at their lowest level. Two or more annual treatments and combinations of cutting and herbicide are more effective than single treatments or even single annual treatments.
Mechanical Treatment: Cutting early in the summer, allowing the rhizomes to regenerate a second crop of fronds, then recutting will deplete the resources of the rhizome much faster than a single cutting. However, single, annual cuttings or deep plowing can be effective during midsummer."
Utah State Bracken Fern Article
You can choose between repeatedly cutting or applying herbicide. If you go the herbicide route, I would apply it to fronds of at least 18 inches, following the label on the product exactly. I would keep the sheep out until the plant had completely died and make sure there aren't any dried fronds left. Either way, marking the area with flags or by placing a pin on an electronic map so I could recheck the area and control as needed. It will take a while to control; consistency over a few years is key!
You can reach out to me directly if you have any follow-up questions.
Sincerely,
Hayley White
<personal data hidden>
