All but the thickest of grass pastures and hayfields are being invaded. Invaded by winter annual or biennial weeds like buttercup, chickweed, henbit (and its cousin deadnettle), musk or nodding thistle and poison hemlock. All are winter annuals except for musk thistle, which is a biennial – meaning it takes two years to complete its lifecycle. These plants can be very competitive with our perennial cool season grasses, especially in new seedings. Mowing these weeds is generally ineffective, but they can easily be controlled with common broadleaf herbicides in the coming weeks if we get temperatures approaching 60o F. These weeds can be recognized pretty easily (with a little coaching, which is just about to happen, so read on).
Every year, I personally struggle with identifying these weeds, especially early enough to have a meaningful chance at control. I am especially motivated this year as I am helping a producer nurse a few hundred acres of newly seeded orchardgrass and bluegrass through to spring.
This article will focus on five very common winter weeds of pasture: buttercup, common chickweed, henbit, purple deadnettle and poison hemlock. To determine the appropriate herbicides to use, see “Broadleaf Weeds of Kentucky Pastures (AGR-207)” by UK’s Dr. J.D.Green and Dr. Bill Witt. ~ Jimmy Henning, Farmers Pride
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- Poison hemlock grows in patches in fields and has a fern-like appearance with triangular, dark green leaves at a vegetative stage. At later stages, stems have a characteristic purple mottling.
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- Common chickweed. Leaves are shiny and small, about a quarter inch across or less. This weed often grows in dense mats at the soil surface.
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- Vegetative purple deadnettle (above, right). Leaves are about ½ to ¾ inch across and are more heart shaped and less ‘lobed’ than henbit. Control for both is similar.
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- Buttercup should be vegetative to get good herbicidal control. Leaves are shiny and about the size of a fingertip.
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- Vegetative henbit is easily confused with purple deadnettle which is a closely related species. Leaves are 1/2 to 3/4 inch across but are more ‘lobed’ than deadnettle. In the vegetative stage, leaves are at the end of a petiole, or stem. When flowering, leaves are directly attached to the elongating stem.
Kentucky Forage News 
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