Download PalmerAmaranth - Escambia County Extension

Palmer Amaranth (Palmer amaranth)
Palmer Amaranth, a type of pigweed, is invading the Southeast. It is a very troublesome weed
for us because it is fast growing, produces a lot of seed and easily develops herbicide resistance.
Palmer is a summer annual weed that can grow up to 10 feet tall. Each female plant can produce
up to 500,000 seeds. Populations of this weed have developed resistance to 4 different classes of
herbicides, including glyphosate or “Round-Up”. There are other types of pigweed in Florida,
such as spiny and redroot pigweed, so you must be able to positively distinguish Palmer
Amaranth from others.
Here as the main differences:
1. Petioles (or stalks joining leaves to the stem) are as long or longer than the leaf blades.
2. The plant has long terminal inflorescence (cluster of flowers on top of the stem).
3. They have prominent white veins on the lower surface of the leaves.
4. They have hairless leaves.
5. They are faster growing than other pigweeds.
If you have identified palmer amaranth in your field, treat with glyphosate. If the pigweed
survives, then quickly hand-weed the female plants as soon as possible. Even if just a few plants
survive this year, next year you could have thousands more. Palmer Amaranth is very difficult to
control but by employing sound IPM principles it can be managed. Refer to
http://edis.ifas.ufl.edu/ag346 for identification and control measures.
Jennifer Bearden
Okaloosa County Extension Office
[email protected]
850-689-5850