Redroot pigweed
Amaranthus retroflexus L.                         Pigweed Family

Key identifying traits

• Leaves have prominent veins and are lance shaped, sometimes turning a reddish color

• Plants grow 2-6’ in height

• Lower stems are normally red or red striped

• Flowers are small and green and flower clusters are full of stiff spike-like bracts

• Seeds are small, black and shiny

Biology and ecology

• An annual plant reproducing by seed

• Redroot pigweed is a very prolific seed producer

• Germination can occur any time during the growing season when there is adequate soil moisture

• Due to the spiny bracts it is undesirable in hay crops

• This plant is a species native to tropical America and now widespread through the U.S.

• Pigweeds can be high in nitrates and toxic to livestock

Control

Prevention – Learn to identify plants; start monitoring early in the season

Biological – No known biological control in our area

Cultural – Planting a competitive grass or other cover crop

Mechanical – Being an annual plant mowing or tillage will work good for control if done before plant flower and produce seed

Chemical –There are many herbicides listed for control of pigweeds-products with dicamba such as “Weedmaster” are recommended. Also refer to the PNW Weed Management handbook for others.

Richard Old, XID Services, Inc.

Richard Old, XID Services, Inc.

Richard Old, XID Services, Inc.

Richard Old, XID Services, Inc.

Where found – Scattered areas throughout Stevens County and seen quite frequently in abandoned crop fields and gardens.

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