Page 116 - AG 7-2011 Revised 2016

Drawing by Andrew Schaible Russian Thistle
(Salsola australis)
Photo Courtesy of PBI/Gordon Corp. Russian thistle is a bushy summer annual with many slender upward
stems that become wood-like once mature. Stems vary from 8 to 36
inches in length and usually have reddish to purplish stripes.
The single, inconspicuous flowers lack petals and are found in most
leaf axils above a pair of small spine-tipped bracts, together called the
“involucre”.
After the plant dries, the base of the stem becomes brittle and breaks off
at soil level in fall and early winter.
Russian thistle is found throughout the western United States and is
particularly well adapted to the climate of California.

immature stage
Integrated Pest Management Control Recommendations
Cultural Practices:
Mowing or destroying young plants can prevent seed production. Avoid dicing or loosening the soil in abandoned areas
because loose soil is necessary for Russian thistle germination. Planting competitive, more desirable species can be an
effective method of preventing Russian thistle.
Herbicide Use:
There are many herbicides that will control Russian thistle in agricultural crops and noncrop areas. Aim treatments at
controlling the immature plants to prevent them from reaching seed production.

Redroot Pigweed
(Amaranthus retroflexus)
Redroot pigweed is a summer annual and is commonly found throughout
California. Redroot pigweed can usually be found in cultivated land and
roadside ditches. Cotyledons are long and narrow with red undersides.
First true leaves are much broader than the seed leaves and have
notched tips. Mature plants grow from 3 to 7 feet tall.
Stalked leaves have prominent veins.
Inconspicuous flowers with green bracts form dense, terminal clusters on
upper branches. The plant gets it’s name from having a reddish taproot.

immature stage

Integrated Pest Management Control Recommendations

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