Weed overtakes animal-free pasture

Asked September 7, 2015, 5:33 PM EDT

This pictured, thick stalked, fast growing weed has overtaken a pasture after the previous owner moved the animals in late July. Can you identify the weed and suggest the best way to control? I mowed them yesterday, but the stalks are so thick, some we incompletely cut.

Jefferson County Tennessee

1 Response

It is one of the pigweeds, likely Spiny Amaranth (Amaranthus spinosus) which is sometimes called careless weed. Look for pairs of spines at the base of the leaf petiole and the central stem. If they are not present, then it may be one of the other pigweeds. The best defense against any of these pigweeds in a pasture situation is to have a healthy stand of grass and not overgraze. Practices that promote strong, healthy pastures include having the correct soil pH, applying the appropriate nutrients based on soil test results, and practicing rotational grazing. Herbicides can be used but with pastures with a heavy seed bank of pigweed seeds, you can get a new flush of weeds after each rain. Contact your local UT Extension office at 865-397-2969 for more information including specific herbicide options.